Antibiotic burden is a critical issue in neonatal intensive care units (NICU) and antibiotic use is considered a quality indicator of neonatal care. Our aim was to optimize antibiotic use through a quality improvement (QI) initiative that included revision of departmental protocols and implementation of a surveillance system based on process indicators.early antibiotics , antibiotics for longer than 3 days (despite negative blood culture), or no antibiotics.This is descriptive study of a cohort of all very low birth weight (VLBW) infants admitted to the NICU from 2014 to 2019. A series of QI interventions were made during the study period and included departmental protocols and the implementation of a surveillance system based on process indicators. The primary outcome was the percentage of VLBW infants who had received p < 0.01) and in infants provided antibiotics for longer than 3 days . Additionally, the percentage of VLBW with “no antibiotics” during their NICU stay increased fivefold .During the study period, a significant relative reduction was seen in the proportion of VLBW infants administered early antibiotics (46%; In our NICU, the implementation of a QI initiative that is based on affordable methods to track process indicators and evaluate the results led into a significant reduction in antibiotic exposure in VLBW infants. This approach is easy to implement in other NICUs as well. Antibiotics are the most frequent drugs prescribed in the NICUs , and whiNotably, NICUs that included some of these measures described in antibiotic stewardship programs and quality improvement (QI) projects have obtained significant reductions in antibiotic use –17. For Although monitoring and measuring antibiotic use are quality indicators in the neonatal setting, there is great variability in their measurement. Moreover, there is uncertainty about the optimal rate of antibiotic use in NICUs , 20. HenAiming to follow international recommendations and best practices for antibiotic use, our NICU implemented a few changes, both in clinical practice and related process indicators. Here, we describe antibiotic use as a process indicator and our primary objective was to assess changes in the following variables between 2014–2019: (1) frequency of antibiotic use in the first three days of life in very low birth weight (VLBW) infants; (2) its continuation beyond the third day of life despite negative blood culture; and (3) proportion of VLBW infants who were not administered antibiotics from birth till hospital discharge. Our secondary objective was to evaluate variations in critical neonatal outcomes over the study period as an indicator of the safety of the changes.The study was performed at the NICU of the 12 de Octubre University Hospital, Madrid, Spain. The NICU is a level III C unit, i.e., maximum complexity level as per the Spanish Society of Neonatology. It is also a regional and national referral center with 44 beds, including 19 intensive care beds. The unit cares for surgical and non-surgical preterm neonates and term neonates who are sick, with nearly 800 admissions annually, about 100 of whom are VLBW.Clinical practice in the unit is based on departmental guidelines, with documents being evidence-based and updated periodically. Guidelines are approved as per internal standard operating procedures. Each guideline and its updates are personally notified to the staff by e-mail and are presented during academic meetings with neonatologists, pediatric residents, research nurses, and NICU nurses. All guidelines are available on paper and in electronic form on the NICU's cloud platform. During the study period, all medical records and drug prescriptions were registered in paper charts.If antibiotics are indicated by neonatologist, one sample for blood culture (at least 1 cc) is obtained before the administration. Blood culture is collected by a nurse, from venipuncture and or during insertion of peripherally inserted central catheter. It is only obtained by the neonatologist if its during umbilical catheter insertion. The volume obtained is registered in medical charts to assess its reliability. Blood cultures are immediately delivered at the microbiology department, where optimized enriched culture media with antimicrobial properties and continuous-read detection systems are used. In the scenario of EOS, our unit use C-reactive protein as a biomarker, is obtained at discretion of the attending neonatologist, the decision of starting antibiotics it is not made based on C-reactive protein values.The NICU has made two updates to the VLBW antibiotic use policy:From December 2014, the duration of early antibiotic use in VLBW infants was shortened based on emerging literature. This clinical practice was notified as an update to the guidelines on the care of VLBW in March 2015, which stated that antibiotics , started at birth, should be suspended at 72 h if blood cultures were negative. Additionally, the time of stopping must be included in the discharge report.A guideline regarding antibiotic therapy at birth in VLBW infants was developed between November 2017 and January of 2018, and was presented to the NICU by the end of January 2018. The document emphasized that antibiotics should not be started after birth if all of the following criteria were met, namely, birth by cesarean delivery, absence of signs of chorioamnionitis, absence of any rupture of membranes before delivery.Since 2017, our NICU adopted certain process indicators used by the Pediatrix Group  to evaluEarly antibiotics, antibiotics for longer than 3 days, and no antibiotics were used as indicators (definitions below).Since 2017, surveillance of the indicators included the following elements:- Daily audit: During clinical rounds, the antibiotic status of each infant in the NICU is discussed with consultant neonatologists, pediatric residents, and the Heads of the Department.early antibiotics (yes/no), antibiotics for longer than 3 days (yes/no and reason), or no antibiotics (yes/no).- Patient report: At discharge, the chief of the department verifies the medical records and the antibiotics administered to the infant from birth until discharge. The discharge report includes information on whether the infant had received - Coding: At discharge, all indicators were checked, coded, and included in the database of the unit by the chief of the department.- Annual feedback: Annually, the chief of the department analyzed the NICU's database and compared process indicators with data from the Pediatrix group. The results were evaluated, communicated to the staff, and sent to the hospital's director, as part of the self-assessment report.This was a follow-up study of a cohort of all inborn VLBW infants, with birth weight (BW) between 500–1500 g, admitted since birth to the NICU, 12 de Octubre University Hospital, from 01 January 2014, to 31 December 2019. Neonates with malformations incompatible with life were excluded. The study period included a retrospective data collection period from 2014 to 2016, before the start of the surveillance system. For this subcohort, data on process indicators were retrieved from unit medical records. A prospective data collection system was used for the period 2017–2019, i.e., since the implementation of the surveillance system in 2017.early antibiotics, antibiotics for longer than 3 days, or no antibiotics. The definitions are identical to those used by the Pediatrix Group, as this ensures consistency with existing data and enables comparison with other units. Early antibiotics was defined as the proportion of infants exposed to ampicillin, gentamicin, or cefotaxime on the day of birth or on days 1 or 2 after birth. Antibiotics for longer than 3 days indicated the proportion of infants who were administered ampicillin, gentamicin, or cefotaxime for longer than 3 days despite negative blood culture  stage ≥ III or those that needed treatment; NEC Bell's Stage ≥ II; brain injury as intraventricular hemorrhage (grade three or associated with hemorrhagic infarction). To assess morbidity and mortality, we used a composite outcome of late mortality and one of four major morbidities .EOS was sepsis diagnosed by blood culture within 3 days of birth while LOS was defined as sepsis occurring after the third day of life with positive blood culture. Severity of illness was assessed using the clinical risk index for babies (CRIB) , which iAn increase in the length of NICU stay, due to an adverse event attributable to changes in clinical practice was evaluated as a safety measure.Data was collected from clinical records and the unit database. Variables such as prenatal history, GA, BW, APGAR score, delivery room resuscitation, CRIB, and the evaluated measures were exported to an anonymous database.p-value of < 0.05 was considered statistically significant. SAS/STAT software, Version 9.4  was used for analyses.This manuscript adheres to the standards for QI excellence (SQUIRE) 2.0 guidelines , 23. DesStatistical process control charts (SPC) were created  to display and analyze data over time. The following rules were used to determine special cause variation (SCV): one point outside the upper or lower control limits, two of three points beyond 2 SD from the mean on the same side of the center line (CL), four of five successive points beyond 1 SD from the mean on the same side of the CL, eight successive points on the same side of the CL, or six successive increasing or decreasing points .We identified 638 infants with BW between 500 and 1,500 g during the study period. Of these, 50 were excluded as 42 were born in other maternities and 8 had insufficient data in their medical charts. Thus, data from 588 VLBW infants were included in the analysis. This cohort had a mean GA of 28.6 weeks (SD 2.8), and a mean BW of 1,042 g (SD 282).p-values > 0.05).Infant and maternal characteristics are shown in no antibiotics) between birth and discharge increased, regardless of newborn characteristics, from 6% in 2014 to 30% in 2019  (The percentage of newborns who were not administered antibiotics (< 0.001) .early antibiotics decreased from 91% in 2014 to 49% in 2019  (The proportion of infants provided < 0.001) . SCV was< 0.001)  in threeantibiotics for longer than 3 days, from 53% in 2014 to 5% in 2019   . On the < 0.001) , SCV wasn = 21). Thus, data from the remaining infants (n = 567) were used in the analysis  between the first year and the following years. An increase in the incidence of ROP (stage ≥ III or those treated in the last year) (p < 0.001) was also noted. No differences over time were seen in LOS or hospital stay.No significant changes in morbidity or late mortality were identified during analysis of the composite variable or each of its components, except for the decrease in the incidence of NEC (p = 0.01) and late mortality  in 2017 had a significant effect on early antibiotics, which was carried over to the second clinical practical change, namely, no antibiotics for VLBW with low risk of EOS. However, the effects of both interventions overlapped in the beginning of 2018 when the first annual feedback was obtained and shared with the unit's staff. The evolution of the indicators over time reflects the fact that these interventions reinforce each other and help reduce antibiotic use. We believe that the high acceptance rate of the measures implemented in our unit is related to their low cost and simplicity, as well as to the culture of change established in our NICU.During the study period, three interventions were introduced, namely, implementation of an antibiotic use surveillance system and improvement of two departmental protocols. Strikingly, these practical changes related to early suspension of antibiotics had a positive effect not only on The increase in ROP requiring treatment during 2019 is not attributable to the changes in antibiotic use; rather, it may be due to a change of the indications of ROP treatment with the new anti-vascular endothelial growth factor. Therefore, the number of infants treated increased but not the severity of ROP per se.early antibiotics for the period 2014–2019, i.e., from 91 to 50%. Likewise, antibiotics for longer than 3 days decreased from 53 to 5% compared to the 35 to 28% reported by the Pediatrix group  we report a greater reduction in the use of ix group .early antibiotics in infants born at <35 weeks, and doubled the percentage of infants discharged without receiving antibiotics . In our cohort, these values were, respectively, 47% and a fivefold increase. Additionally, that NICU achieved its goal of reducing antibiotic use rate by 20% and this has remained stable over time. The authors state that the observed variations in antibiotic use rate over time correspond to shifts in process indicators and conclude that both measures facilitated a positive impact on their main objective. They also conclude that their results are due to several factors such as frequent audits with feedback, dissemination of antibiotic use rate, and staff education.One of the NICUs participating in the Vermont Oxford Network's “Choosing Antibiotics Wisely” initiative  publisheAlthough our study design did not include antibiotic use rate, additional studies focused on quality indicators can help achieve favorable results in other units' efforts to optimize antibiotic use.We can learn from previous QI initiatives and stewardship programs that including multiple key elements, NICUs can reduce their antibiotic use, but most importantly is that the shift on the thinking on antibiotics, it is what strengthens those initiatives –15, 17. With so many factors justifying or limiting antibiotic use, a crucial issue is the break-even point that NICUs should achieve , 26. It In conclusion, with this initiative, we propose a simple and low-cost method to reduce antibiotic use. Through a QI initiative that includes elements described in European guidelines, and by comparing our results with those available for other networks, we have achieved a significant decrease in the use of antibiotics in VLBW infants. To date, there is no registry in Spain that includes the use of antibiotics in NICUs; hence, this aspect has been considered as a quality process indicator by other groups and has been included in the European Guidelines as one of the core elements for optimization of antimicrobial use . Its incThe original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author/s.The studies involving human participants were reviewed and approved by Ethics Committee of the 12 de Octubre University Hospital. Written informed consent from the participants' legal guardian/next of kin was not required to participate in this study in accordance with the national legislation and the institutional requirements.CM-B, CP-A, and JD conceptualized the design of the study, coordinated and supervised data collection, drafted the initial manuscript, and reviewed the manuscript. BM-A and EB-S contributed to the acquisition, analysis, interpretation of data, and reviewed the manuscript. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Tracheal aspirates (TA) are frequently obtained in the pediatric intensive care unit (PICU); however, no data exists on the frequency or clinical management of multiple TA cultures on the same PICU patient. In this study, we describe the frequency of repeat TAs in PICU patients, the emergence of multidrug resistant organisms (MDRO), frequently cultured pathogens of TAs, and associated antibiotic prescribing patterns.We identified 70 PICU patients between 2018-2019 who met our criteria for retrospective chart review with ≥ 2 TAs obtained during their hospitalization. The following information was collected: patient demographics, number of TAs per patient, microbiology with susceptibilities, antibiotic use, and clinical data summarizing patient condition. Descriptive statistics established the frequency and time between initial and repeat TAs, reason for collection, antibiotic exposure, and frequency of MDRO development.Pseudomonas aeruginosa (n=32), Methicillin-susceptible Staphylococcus aureus (n=16), and Klebsiella oxytoca (n=11) comprising the top pathogens . Eleven of the 15 patients (73.3%) had the same organism detected on ≥ 2 separate cultures. A total of 616 antibiotic days were prescribed with 149 (24%) antibiotic days prescribed for the TA result specifically. Six (40%) patients developed a MDRO after a median of 14.5 antibiotic days .Preliminary data on 15 patients showed 90 total TA cultures, with a median of 4  cultures per patient during their PICU stay . The median days between cultures was 10 . Most patients were < 5 years of age , male , and were admitted to the medical ICU service . Fever (46%) was the most common reason for TA collection followed by vital sign changes and secretion burden (34% and 32% respectively). A total of 133 organisms were isolated, with Repeat TAs are performed in the PICU, often identifying the same pathogen repeatedly, likely representing colonization. Development of resistance is common and only one-fourth of TAs are directly treated with antibiotics. These data provide an opportunity to further explore clinical criteria to maximize the impact of TA cultures in the PICU.Brian R. Lee, PhD, MPH, CDC: Grant/Research Support|Merck: Grant/Research Support Rangaraj Selvarangan, BVSc, PhD, D(ABMM), FIDSA, F(AAM), BioFire: Grant/Research Support|Luminex: Grant/Research Support.


Currently, in civil engineering, the relevant direction is to minimize the cost of the manufacture of the hollow structures of annular sections, as well as their construction and installation efficiency. To optimize the costs associated with building products and structures, it is proposed to apply the technology of vibrocentrifugation, to reconsider and comprehensively approach the raw materials for the manufacture of such products and structures. The purpose of this study is a theoretical substantiation and experimental verification with analytical numerical confirmation of the possibility of creating improved variotropic structures of vibrocentrifuged concrete nano-modified with ground granulated blast-furnace slag. The study used the methods of electron microscopy, laser granulometry, and X-ray diffraction. Slag activation was carried out in a planetary ball mill; samples were prepared on a special installation developed by the authors—a vibrocentrifuge. The optimal and effective prescription–technological factors were experimentally derived and confirmed at the microlevel using structural analysis. The mathematical dependencies among the composition, macrostructure, microstructure, and final properties of vibrocentrifuged concrete nano-modified by slag are determined. Empirical relationships were identified to express the variation of some mechanical parameters and identify the relationship between them and the composition of the mixture. The optimal dosage of slag was determined, which is 40%. Increases in strength indicators ranged from 16% to 27, density—3%. Nowadays, the actual problem of current construction is the need for new building materials, structures, products, and technologies to obtain the most efficient buildings and structures in terms of ecology, energy saving, manufacturability, minimization of labor intensity, material consumption, resource intensity, and energy intensity. In this regard, the most reliable building structures, which contain small sections, are promising, allowing the construction industry to significantly reduce the weight of the resulting buildings and structures, which at the same time have high performance characteristics and are characterized by efficiency at all stages of the life cycle of construction products and construction processes.The most important factor in the effective replacement of part of the cement composition with blast-furnace slag is the correct selection and grinding of the components. In ,2,3, slaThis study of the strength properties of the prototypes showed that it is possible to replace up to 85% of clinker with slag, while the final material demonstrates indicators that are not inferior to concrete on clinker binders. The most significant drawback of the samples is the lack of the “required strength in the early stages of hardening” ,2,3,4.2/g. At this value, the highest tensile strength values were observed [An analysis of the effect of slag dispersion on the manifestation of hydraulic activity when added to cement was carried out in . A ball observed ,5.In , a mechaThe issue of studying the influence of the specific surface area of ground granulated slag was also studied in ,9,10,11.In many works ,30,31,32The effect of the hardening temperature on the concrete properties with the addition of ground granulated blast-furnace slag (GGBFS) was investigated in ,28,30, iThus, during the study, it was found that an increase in the hydration temperature does not have an important effect on the “strength properties of the samples” ,17.The work  presentsThe issue of the durability of concretes and mortars based on slag has also received much attention ,34,35,36Special focus should also be paid to the combined effect of slag and other dispersed additives on the properties of composites. Fly ash, nanosilica, lime, and gypsum, together with slag, improve the individual properties of composites based on them ,40,41,42Thus, our goal is a comprehensive development aimed at the enhancement of the characteristics of the building materials used in obtaining effective building structures of buildings and structures. One of the most effective types of building structure is the hollow structures with an annular section, primarily obtained via centrifugal compaction methods . This meA relevant research direction is also minimizing the cost of manufacture of these products and their construction and installation efficiency. To optimize the cost of building products and structures, first, it is necessary to review and comprehensively approach the raw materials, as well as the technology for manufacturing such products and structures. If, from the point of view of technology, we can already talk about the effectiveness of using the vibrocentrifugation method instead of simple centrifugation, then the question regarding building materials is still open.In this regard, the working hypothesis of the study is the development of the most cost-effective formulation with the maximum use of cheap raw materials, which can primarily be obtained from industrial and other types of waste used for manufacturing such products. One of the most demanded is the use of the production waste of the fuel and energy complex, i.e., production waste obtained during the operation of industrial and agro-industrial facilities, which is discussed in ,54,55,56In the present work, the influence of such waste as GBFS on the possibility of obtaining the most effective variotropic structure of products and structures with an annular section obtained through centrifugal compaction methods is studied. According to the stages of work, the most important aspects should be noted, such as the prescription  and the technological . the evaluation of the structural efficiency of such a method using prescription and technological methods due to mathematical, statistical, and resulting processing and other analytical tools to determine the most desirable modes and recipes is necessary.And, finally, the constructive aspect, expressed in terms of the construction and installation efficiency and practical applicability of the developed approaches is discussed. At the same time, the structural aspect should be considered not only at the macro level during the formation of coarse variotropic structures, but also from the point of view of microscopic examination to understand the fundamental processes that occur during the interaction of raw materials, both with the use of industrial waste and with more standard typical components and raw materials.The purpose of this research is the study of the combination of vibrocentrifugation technology and the nano-modification of concrete with blast-furnace granulated slag, i.e., the theoretical and experimental verification of the creation of variotropic nano-modified structures.The novelty of the study is as follows.The optimal recipe-technological parameters of the process of nano-modification by blast-furnace granulated slag of vibrocentrifuged concrete have been determined.Microscopic examination has proven the improvement of the microstructure and macrostructure of new concrete by achieving a denser packing of particles in the working layers of a variotropic section.New theoretical and experimental dependences of the structure and properties of vibrocentrifuged concretes on the parameters of its nano-modification have been obtained.The scientific novelty of the study is the theoretically substantiated and experimentally and analytically confirmed possibility of obtaining a new, improved variotropic concrete with an improved structure at the macro- and microlevels due to the complex effect of nanomodification with granulated blast-furnace slag and optimal vibrocentrifuging compaction.The research question underlying this article is the creation of a new type of vibrocentrifuged concrete with an improved variotropic structure obtained by its nanomodification with granulated blast-furnace slag. The subject of the study is the very possibility of obtaining such a concrete, as well as the choice of the rational formulation and technological parameters for its production.The scheme of this experimental study is shown in 2/kg, cement paste normal density—25%, fineness of grinding, passage through a sieve No. 008—95.7%, setting time—165–230 min, tensile strength in bending—4.6 MPa (after 2 days) and 7.6 MPa (after 28 days), and compressive strength—24.5 MPa (after 2 days) and 55.2 MPa (after 28 days). The mineralogical composition of Portland cement is presented in Portland cement grade PC 500 D0 produced by OAO Novoroscement  was used as a binder in this study. The main Portland cement properties are as follows: specific surface—330 m3, true density—2675 kg/m3, and content of dust and clay particles—1.1%, clay content in lumps—0.15%, and it is free of organic and contaminants. Grain composition and modulus of the sand sizes are given in Quartz sand manufactured by OAO Arkhipovsky Quarry  was used as a fine aggregate. The physical characteristics of the sand are as follows: bulk density—1578 kg/mGranite crushed stone produced by Pavlovsknerud JSC  was used as a large dense aggregate. Granulated blast-furnace slag (GBFS) produced by NLMK PJSC  was used as a mineral additive. The chemical composition of the blast-furnace slag is presented in Sodium hydroxide, NaOH, manufactured by PJSC Khimprom  was used as a chemical additive. The amount of this additive used for all experimental compositions was 8% by weight of the binder components. During the experimental studies, the sodium hydroxide powder was first dissolved in a certain small volume of mixing water, and then the resulting solution was mixed with the entire volume of mixing water.To study the dispersity and morphology of the samples, electron microscopy and laser granulometry were used. The modified hardened cement paste structure was studied using a ZEISS CrossBeam 340 (Carl Zeiss Microscopy GmbH (Factory), Jena, Germany). The granulometric composition of the activated slag was evaluated using a MicroSizer-201C laser particle analyzer .The study of the phase composition of the GBFS was carried out using X-ray diffraction on the device “Difrey” . The experimental curves were obtained with chromium radiation at room temperature. The shooting parameters on the X-ray tube were: voltage—25 kW, current—4 mA.Slag activation (grinding) was carried out in the Activator-4M planetary ball mill .The components of the slag contribute differently to the hydration process, which is determined by the interaction of some compounds with other components of the system. The binder properties of the GBFS were evaluated to predict their use more accurately in the composition of the final material. The evaluation of the binding properties of slags is determined from several indicators, such as the basicity modulus, activity index, basicity factor, and quality factor.The basicity modulus was calculated using Equation (1):When the value of The activity index is used to compare the hydraulic properties of slags. With an increase in the activity index, the hydraulic properties of slags increase. The higher the activity index, the greater the rate of curing.The calculation of the activity index was carried out according to Equation (2):The basicity coefficient shows the ratio of the amount of calcium oxide to silicon oxide.The calculation of the basicity coefficient was carried out according to Equation (3):The quality factor is used to determine the grade of blast-furnace slag according to GOST 3476 “Blast-furnace and electro thermos phosphoric granulated slags for cement production. Specifications”. It is noted that the higher the index, the higher the hydraulic activity of the slag [The calculation of the quality factor was carried out according to Equation (4):For the manufacture of vibrocentrifuged samples, a special installation was used—a laboratory vibrocentrifuge . The cenThe integral and differential characteristics of concrete were determined according to the method . “IntegrFor the manufacture and further testing of samples in this study, the same equipment and measuring instruments were used as in .-to determine the integral characteristics—four cubes with an edge of 150 mm for compressive strength; one prism of 150 mm × 150 mm × 600 mm for the study of bending tensile strength; two prisms of 150 mm × 150 mm × 600 mm for axial compressive strength; and two prisms of 150 mm × 150 mm × 600 mm for the study of axial tensile strength; and-to determine the differential characteristics—nine cubes with an edge of 50 mm for compressive strength; nine prisms of 50 mm × 50 mm × 200 mm for the study of bending tensile strength; nine prisms of 50 mm × 50 mm × 200 mm for axial compressive strength; and nine prisms of 50 mm × 50 mm × 200 mm for the study of axial tensile strength.In total, nine vibrocentrifuged prototypes of annular cross-section were manufactured and tested. The dimensions of the cut samples were:All samples were cut and tested in accordance with the requirements of GOST 28570 “Concretes. Methods of strength determination on cores selected from structures”. Detailed schemes for cutting samples for testing from vibrocentrifuged prototypes and a detailed description of the procedure for preparing samples for testing are presented in .The strength of the manufactured samples, in terms of compression, tensile bending, and axial tension, was determined in accordance with the requirements of GOST 10180 “Concretes. Methods for strength determination using reference specimens”, and the axial compressive strength and modulus of elasticity were determined in accordance with the requirements of GOST 24452 “Concretes. Methods of prismatic, compressive strength, modulus of elasticity and Poisson’s ratio determination”. Measurements of the deformations of the concrete of the experimental prisms were carried out using a chain of strain gauges with a side length of 50 mm and dial indicators with a division value of 0.001 mm.Moreover, an additional assessment was made of the variotropic efficiency of vibrocentrifuged concretes modified by the addition of slag. The values of the coefficients of variotropic efficiency were calculated according to the formulas given in For the manufacture of vibrocentrifuged samples with an annular section, heavy concrete of class B30 was designed in accordance with previously developed recommendations . All conBased on the data on the chemical composition of the GBFS, the calculation of indicators that determine the hydraulic properties of the presented material was carried out. The data obtained during the calculation are shown in The amorphous phase (glass phase) is formed as a result of the content of a large amount of silicon in the samples and the method of cooling (granulation). The diffraction pattern obtained during the study of the DHS is shown in 3Mg(SiO4)2) are found; this phase is located in the middle of the sequence of hydraulic activity of substances present in blast-furnace slags and is characterized by low hydraulic properties. It can also be seen that this material contains a large number of amorphous phases. This theoretical justification is in good agreement with [On the diffraction curve of the GBFS sample , the int3MgSiO2) are foThe data on the chemical composition of GBFS, as well as the conducted X-ray phase analysis, allow us to conclude that this GBFS can be used as an astringent mineral component.3, true density—2900 kg/m3.Moreover, additional studies of GBFS were carried out in terms of indicators: moisture content, bulk and true density, and particle size distribution of crushed GBFS. The results of determining the physical properties of GBFS are as follows: humidity—1.9%, bulk density—1055 kg/mTo determine the optimal conditions for the activation (grinding) of GBFS, a number of experimental studies were carried out; to obtain samples of ground slag, grinding of GBFS was carried out at a speed of 400–500 rpm for 10, 20, 30, and 40 min.The particle size distributions of granulated slag after grinding for 10, 20, 30, and 40 min are shown in It should be noted that, with an increase in the distribution time, significant changes in the size distribution of particles are observed. The observed effect can be explained by the fact that the Activator-4M ball mill, provided that the parameters and activation modes are rationalized, allows the equipment to be adjusted in such a way as to obtain a polydisperse particle distribution pattern. Such a picture, within certain limits, makes it possible to achieve a qualitative structure with the densest packing of particles; however, if rational activation ranges are exceeded, it can cause certain harm, due to the excessive grinding of functional particles. The influence of the grinding time of GBFS on its granulometric characteristics is reflected in According to , an impoTo determine the most desirable granulometric characteristics of the slag and the time of its grinding, additional studies were carried out. Four series of six sample-cubes with dimensions of 100 × 100 × 100 mm were made according to GOST 10180-2012 “Concretes. Methods for strength determination using reference specimens”. All prototypes were made from a concrete mixture with the same composition: one part of cement, three parts of sand, water–cement ratio 0.5, dosage of mineral additive in the amount of 15% replacement by weight of cement. The results of the tests of the sample-cubes for compressive strength are shown in Following the data of the results of the granulometric tests and the strength characteristics of the sample cubes, the most desirable granulometry contains GBFS, crushed for 30 min. Thus, in the future, for the implementation of the nano-modification of vibrocentrifuged concrete, a GBFS activated for 30 min was used.During the experimental studies, part of the cement was replaced with activated slag in amounts of 10%, 20%, 30%, 40%, and 50%. The experimental results of the effect of the GBFS additive on the integral physical, mechanical, and strain characteristics of modified vibrocentrifuged concrete are presented in -7, 13, 14, 17, and 9%, respectively, for compressive strength;-5, 12, 12, 14, and 5%, respectively, for axial compressive strength;-6, 13, 15, 22, and 14%, respectively, for tensile strength in bending;-12, 16, 16, 20, and 10%, respectively, for axial tensile strength; and-6, 12, 13, 19, and 4%, respectively, for the modulus of elasticity.Changes in the differential physical–mechanical and deformative characteristics are shown in The outer layer of vibrocentrifuged concrete acquires a denser structure as a result of the action of the nano-modifier. The middle layer is also compacted simultaneously with hardening, while the inner layer remains, for example, at the same level due to the physical impact of centrifugal forces and the objective impossibility of controlling its characteristics with the help of nano-modification.The mechanism of compaction and hardening with the help of a nano-modifier of the outer and middle layers of vibrocentrifuged concrete can be explained by achieving a denser packing of particles, in which nano-modifier particles act as crystallization centers. There is a redistribution of hydration processes and improvement of the structure formation of the binder-aggregate system, especially at the interfaces.Thus, the action of the nano-modifier enhances the positive impact of the technological method of vibrocentrifugation, and all this leads to a notable improvement in the structure and compaction of the working layers of such concrete and to an increase in the strength characteristics, both differential and integral for elements made of such an improved variotropic concrete.It can be seen from After analyzing the dependence of the change in the difference between the compressive strength as a percentage for different layers, a tendency was established to reduce the difference between the middle and inner layers of vibrocentrifuged concrete modified with the addition of GBFS in the amount of 40% .The axial compressive strength of the inner layer of vibrocentrifuged concrete varied between 21.4 MPa and 22.3 MPa. As for the axial compressive strength values for the middle layer of modified concretes, the increases in compressive strength when replacing part of the cement with 10, 20, 30, 40, and 50% GBFS compared to the control composition were 10, 30, 39, 64, and 36%, respectively. The increases in axial compressive strength for the outer layer were 0, 4, 4, 12, and 3%, respectively.The differences between the axial compressive strength as a percentage for different layers is shown in The flexural tensile strength of the inner layer of vibrocentrifuged concrete varied between 3.3 MPa and 3.4 MPa. As for the values of tensile strength in bending for the middle layer of modified concretes, the increments in tensile strength in bending when replacing part of the cement with 10, 20, 30, 40, and 50% GBFS compared to the control composition were 9, 30, 35, 61, and 39%, respectively. The increases in axial compressive strength for the outer layer were 1, 2, 3, 6, and 2%, respectively.The differences between the tensile strength in bending as a percentage for different layers is shown in The axial tensile strength of the inner layer of vibrocentrifuged concrete varied between 2.0 MPa and 2.1 Mpa. As for the axial tensile strength values for the middle layer of modified concretes, the increases in axial tensile strength when replacing part of the cement with 10, 20, 30, 40, and 50% GBFS compared to the control composition were 6, 41, 44, 66, and 47%, respectively. The increases in axial tensile strength for the outer layer were 2, 4, 6, 8, and 4%, respectively.The differences between the tensile strength in bending as a percentage for different layers is shown in The modulus of elasticity of the inner layer of vibrocentrifuged concrete varied between 25 MPa and 25.9 MPa. As for the values of the modulus of elasticity for the middle layer of modified concrete, the increase in the modulus of elasticity when replacing part of the cement with 10, 20, 30, 40, and 50% GBFS compared to the control composition was 7, 24, 28, 44, and 31%, respectively. The increases in axial tensile strength for the outer layer were 8, 8, 9, 14, and 5%, respectively.The differences between the tensile strength in bending as a percentage for different layers is shown in Thus, from analyzing the experimental data, it was found that, at a dosage of between 0 and 40% of the cement substitution with GBFS, a stable increase in strength and deformation of integral characteristics by up to 22% is observed; however, at a dosage of more than 40%, a sharp decrease in these characteristics is observed. This is explained by the fact that, with a decrease in the proportion of cement, the ratio of reactive minerals of cement and slag does not provide an increase in the volume fraction of the products of the pozzolanic reaction, which contributes to an increase in the porosity of the hardened cement paste and, consequently, to a decrease in its strength.Moreover, the modification of the GBFS makes it possible to increase the variotropic efficiency of the vibrocentrifuged concrete by reducing the differences between the strength characteristics of the middle and outer layers.The values of the calculated coefficients of variotropic efficiency are presented in Based on the test results, “stress–strain” diagrams “The optimal value, judging by the characteristic shift of the diagram peak up and to the left, is demonstrated by a sample with a nano-modifier dosage of 40%. Such a qualitative–quantitative picture illustrates the highest strength and lowest deformation characteristics of the resulting concrete. It is possible to explain the obtained effect by detecting an obvious optimum on the graph of the interdependence of the nano-modifier content and quality indicators. It is obvious that, with an increase in the amount of nano-modifier in the composition of concrete, there is also some preparation for a drop in performance after oversaturation with an excess amount of nano-modifier. Thus, after 40%, a certain decline begins, which is illustrated by the established dependence.Obviously, concrete with a nano-modifier dosage of 40%, other things being equal, shows the greatest applicability in the practical industry. Thus, the highest strength characteristics allow it to provide the highest bearing capacity for structures based on it.The deformability, which characterizes the shift of the peak of the diagram to the left, additionally shows that, other things being equal, such nano-modified concrete has the highest elastic modulus. The changes that occur can be explained by an increase in strength characteristics, that is, an increase in stress and a simultaneous decrease in strains indicators, since concrete acquires higher strength. Thus, the ultimate strains of such concrete are correspondingly reduced.Of course, it would be expedient to apply concrete with these improved properties in practice in design and construction. This research of the microstructure was carried out to establish the relationship between the structure of the material and the strength characteristics of concrete. Samples were selected for the study, which were previously tested for compression.In The conducted studies show that the synergistic effect of a prescription factor (nano-modification), and technological impact (vibrocentrifugation) is expressed in a layer-by-layer increase in physical and mechanical characteristics and is explained by the formation of an improved variotropic structure. As a result of nano-modification, additional crystallization centers appear, and a denser packing of particles is formed in the most important layers—the middle and outer ones. Additional vibration during centrifugal compaction with rationally selected parameters results in a redistribution of the nature of variotropy with the values of the middle layer approaching the values of the outer layer. These structural transformations explain the achieved effect in the form of gains in both the integral and differential characteristics of new vibrocentrifuged nano-modified concretes.For further analysis and comparison of the results obtained with the data obtained earlier in ,46,47,48As is known from ,46,47,48In , the autLet us turn our attention to the possibilities of even greater improvement of this effect when exposed at the microlevel. At the microlevel, the picture is somewhat different. It is necessary to consider the specific features of the obtained variotropic structure of concrete mixtures of standard composition. Understanding these features and already possessing certain skills and specifics of the process, we can reliably say, after our study, that the impact with the help of nano-modifying additives, such as blast-furnace granulated slag, leads to an even greater effect, including the ability to achieve a synergistic effect in the formation of improved variotropic structures.Previously, in , we obtaThe nanomodification of the variotropic structure with finely ground blast-furnace granulated slag has shown its high efficiency in terms of results at the macro level. This was confirmed by the results of the laboratory tests of the prototypes. Let us consider the fundamental picture that occurs at the microlevel during the formation of structure and the formation of the properties of such concretes. By analogy with the previously established dependencies ,55, the When summarizing the results of the theoretical and experimental research conducted in this study, the following conclusions can be drawn. Firstly, we have developed previously obtained theoretical and practical results concerning the developed concept of the nano-modification of variotropic concrete structures. The purpose of nanomodification is to obtain concrete with improved characteristics and greater operational reliability.The most desirable prescription–technological factors were experimentally derived and confirmed at the microlevel using structural analysis. Applied and mathematical dependencies among the composition, macrostructure, microstructure, and final properties of the vibrocentrifuged concretes nano-modified by blast-furnace granulated slag were determined. Empirical relationships were identified to express the variation of some mechanical parameters and identify the relationship between them and the composition of the mixture.The optimal dosage of granulated blast-furnace slag for the nano-modification of variotropic vibrocentrifuged concretes was determined, which is 40%.The influence of the optimal dosage of blast-furnace granulated slag on the properties of nano-modified vibrocentrifuged variotropic concretes was revealed, which was reflected in the quantitative ratio as an increase in density of 3%, strength indicators—from 16% to 27% (depending on the type of strength), and elasticity modulus—of 23%.Further prospects for the study were determined, which consist of continuing research on the effect of nano-modifying additives on variotropic vibrocentrifuged concretes, in particular, using even more finely dispersed materials brought to the nano-level: nano-silica, nano-slag, and nano-fly ash, as well as nanosized ash, rice husks, and rice straw.To cover the most problematic areas of the accumulation of various wastes, both industrial and agricultural waste, as well as waste from the fuel and energy complex  and electric power industry), are proposed to be used in concrete technology, and, in view of the proven effectiveness of the use of such additives in concretes of variotropic structures, this direction is proposed to be researched as a priority.


To this end, an experimental program consisting of 24 beams (divided into four groups) was performed, where different parameters was combined . In addition, the effect of the testing temperature on the end debonding phenomenon was investigated with an analytical procedure according to fib Bulletin 90, and the predictions were compared to experimental results. Taking specimens tested at 20 °C as a reference, no considerable change was observed in the ultimate load of the specimens tested below 60 °C (being in the range of epoxy gT), and all specimens failed by FRP rupture. On the other hand, the increase in testing temperature up to 70 and 85 °C was followed by a decrease in the capacity of the strengthened beams and a change in failure mode, moving from FRP rupture to end debonding and concrete crushing. The analytical procedure successfully predicted the occurrence of premature end debonding failure and demonstrated that the effect of temperature on the mechanical properties of materials can be a key factor when predicting the premature end debonding in a NSM joint.This paper aims to evaluate the influence of relatively high service temperatures (near or beyond the glass transition temperature ( Fiber-reinforced polymers (FRPs) have become popular in the construction industry, specifically in repairing and strengthening aged, damaged, or overloaded concrete structures . To this end, different techniques are used in FRP-strengthened structures, namely externally bonded reinforcement (EBR) and near-surface mounted (NSM) techniques ,2,3. In gT), on the mechanical properties of epoxy adhesives [gT. Furthermore, according to fib Bulletin 90 [gT, to avoid any considerable change in the adhesive properties. In addition to design codes, different studies have been performed to define the service temperature in FRP-strengthened systems [gT of the adhesive for Externally Bonded Reinforcement (EBR) systems. Michels et al. [gT. To avoid the effect of temperature in the creep of epoxies, Ferrier et al. [gT. Moreover, in similar studies [gT. These limitations are related to the EBR system, while for the NSM technique no specific limitation has been stated.In FRP-strengthened reinforced concrete (RC) beams, three different materials are involved to transfer the shear load between the concrete and FRP, namely FRP, bonding material , and concrete. Therefore, the performance of the FRP-strengthened RC structure is not only dependent on the interaction between these materials but also on the individual properties of each material, and how they are affected by external factors. Among these materials, monitoring the performance of the epoxy adhesive is very important due to the influence of the environmental conditions, especially temperature changes near or beyond the glass-transition temperature . The results showed that the ultimate load remained mostly unchanged for testing temperatures below 62 °C, and it was reduced by 20% for testing temperatures beyond 70 °C. This reduction in load capacity was followed by the failure mode changing from cohesive in concrete to adhesive at the concrete–epoxy interface. It is important to mention that extensive research has been performed on the effect of elevated temperatures on the performance of an FRP–concrete joint, as well as on the behavior of the constituent materials ,17. Howe Krzywoń  investiggT of epoxy is almost missing in the literature. Silva et al. [gT equal to 55 °C. According to the experimental results, the maximum load capacity was observed in the slab at 40 °C, which was attributed to a possible post-curing effect in the epoxy resin. With the increase in the temperature up to 80 °C, the capacity of the slab decreased by 12% and the failure mode changed from concrete crushing to cohesive failure at the epoxy. In a more recent study, Jahani et al. [Moving from the EBR system to NSM, many studies have been done to evaluate the flexural performance of NSM FRP-strengthened RC beams at room temperature ,24,25,26a et al.  studied i et al.  investigBased on the scarce literature on the effect of high service temperatures on the flexural performance of NSM carbon FRP (CFRP)-strengthened beams, and its consequences on possible end debonding phenomena, this paper collects and presents experimental results on 24 beams tested by the authors, so that different steel reinforcement ratios, service temperatures and concrete grades (compressive strength of concrete) are considered. In this sense, the results are presented and analyzed in terms of load–deflection curves and failure modes. Additionally, the experimental results are compared to analytical predictions on end debonding in which the effect of temperature on epoxy and concrete mechanical properties are included.2, respectively) subjected to 20 and 40 °C. In Group 2, six specimens were tested to evaluate the effect of higher temperatures. To this end, two control beams with a steel reinforcement ratio of 1.14% (at 20 and 70 °C) and four strengthened beams with two CFRP strips  at various temperatures  were cast with a concrete compressive strength of 40.8 Mpa. The specimens in Groups 3 and 4 had a concrete compressive strength of 48.1 Mpa but two different steel reinforcement ratios: ρ = 0.79% and 1.14% for Group 3 and 4, respectively. Group 3 included two control beams and four strengthened beams with two different CFRP ratios  subjected to 20 and 50 °C, thus making a total of 6 beams. Finally, a total of four specimens in Group 4 were distributed as two control beams and two strengthened beams with a CFRP ratio of 0.18%  and subjected to 20 and 50 °C. The test program consisted of a total of 24 specimens divided into four groups, as presented in 2, and the dimensions on the cross-section of the beam were kept constant along the whole experimental campaign.The specimens’ designations are in the form X-Y-Z, where X denotes the type of beam ; Y indicates the number of the Group that the specimen belongs to; And Z stands for the testing temperature. For instance, CB-1-40, refers to the control beam in Group 1 tested at 40 °C. Furthermore, SB3S-3-50 refers to a beam strengthened with three CFRP strips from Group 3 and tested at 50 °C. It should be mentioned that reference to the CFRP ratio in the specimens’ designations is done based on the number of CFRP strips included in the cross-section. However, to have a clearer idea on the amount of CFRP strengthening included in each beam, the CFRP ratio is also presented in fib Bulletin 90 [The beams were tested under a four-point bending configuration see . They haletin 90  recommenc) as shown in Prior to testing, the beams were heated up to the target temperature using heating blankets that were attached to the soffit of the beam. A proportional integral derivative (PID) controller was utilized for the heating process, and Type-T thermocouples, located between the heating blanket and the soffit of the beam, were used as temperature controller sensors. An isolation system  was used to speed the heating process and to ensure a better heat distribution. To record and monitor the temperature variation during the heating process and flexural testing, different temperature gauges were glued on the concrete surface at the top and bottom of the beam, on the surface of the CFRP, and on the surface of the epoxy adhesive see .It should be mentioned that the temperature gauges glued on the surface of the CFRP strip were installed prior to introducing the CFRP strip into the groove, and a thin protection layer was applied to protect them from the wet environment during the curing of the epoxy adhesive. Moreover, temperature gauges glued on the surface of the epoxy adhesive were installed once the epoxy was cured, at the outer part of the section. The tests started when the average temperature in the soffit of the beam was stabilized, almost 24 h after the heating process started, and it was kept constant during the loading see . A genercf), tensile strength (tf), and modulus of elasticity (cE) of the concrete were determined from three cylinder specimens , according to UNE-EN 12390-3 [Three different batches of concrete were used. The details of the concrete batches are shown in  12390-3 , UNE-EN  12390-3 , and AST 12390-3  standardyf), the ultimate stress (uf), and the modulus of elasticity (sE) for each group of specimens are shown in The mechanical properties of the steel bars were obtained from tension tests based on UNE-EN ISO 15630-1 . The yieu,FRPf) of 2251.4 Mpa (CoV = 3.2%), an ultimate tensile strain  of 0.0133 (CoV = 7.2%), and a modulus of elasticity (FRPE) of 169.5 Gpa (CoV = 6.3%) were obtained [CFRP strips, consisting of unidirectional carbon fibers (with a volume content fiber higher than 68%) held together by an epoxy resin, were used to strengthen the specimens . The CFRobtained .gT) of the epoxy was determined based on two well-known available methods, namely differential scanning calorimetry (DSC)  and dynTM E1356 ). Accord–65.3 °C . The tensile properties of the epoxy adhesive were determined by dog-bone specimens following ISO-527-1  specificThe load–deflection curves of the tested beams are shown in According to gT of the epoxy . Similar to the results obtained for Group 1, increasing the testing temperature up to 60 °C did not significantly affect the ultimate load  of the strengthened beams. On the contrary, strengthened specimens tested at temperatures equal to 70 °C and 85 °C showed some reduction in their ultimate load equal to 4.0% and 10.5%, respectively, compared to the corresponding value of the strengthened beam tested at 20 °C (beam SB2S-2-20). Moreover, due to effect of temperature in the mechanical properties of the concrete, ultimate load in the control beam was also reduced (by 3.5%) when the specimen was subjected to 70 °C. gT of the epoxy adhesive, the results from the specimens belonging to Groups 3 and 4 were analyzed. To evaluate the effect of the steel reinforcement ratio and testing temperature just below the gT) had no considerable effect. Therefore, the results suggest that the design service temperature limitation for NSM technique could be increased to values closer to the epoxy gT. Similar to the specimens in Group 1, the increase in the testing temperature up to 50 °C had no effect in the response of the specimens in Groups 3 and 4. According to the experimental results , it can be concluded that the NSM strengthening system is slightly susceptible to temperature variations, as applying temperatures up to 60 °C  and the epoxy may have post-cured [c in The failure mode in all the control (unstrengthened) beams was concrete crushing after yielding of the steel reinforcement (CC), irrespective of the testing temperature. Strengthened specimens belonging to Groups 1, 3, and 4 experienced FRP rupture (FR), and the failure mode did not change with the increase in the testing temperature. Similar behaviors were observed by other authors ,19,33 anst-cured ,33,34. FRepresentative images of the different failure modes are shown in fib bulletin 90 [gT of epoxy .According to experimental observations, up to 60 °C, all strengthened beams failed by FRP rupture without any premature end debonding, which indicates the good performance of the NSM strengthening system for the chosen beam dimensions and setup configuration. Therefore, unlike recommendations for service temperatures of the EBR system , the efEnd debonding is one of the most common failure modes in NSM strengthening techniques, especially in the case of short anchorage length . Therefofib Bulletin 90 [X, has been assumed to be the one at which the moment equals the yielding moment of the unstrengthened control beam, considering the “shift rule”. At that point, the bond capacity of a FRP strip can be obtained as follows:fbdF is the design bond capacity per strip in N, fb is the width of the strip in mm, ra is distance from the longitudinal axis of the strip to the free edge of the beam section in mm, and bl is the available anchorage length of the CFRP strip in mm. In addition, bldτ is the design bond strength of the NSM CFRP strips and can be assumed to be the minimum between the concrete bond strength and the adhesive bond strength as:baα (ranging between 0.5 and 0.85) and bcα (ranging between 0.85 and 1) are product-specific factors for the long-term behavior of the adhesive and concrete, respectively. In this study, 0.85 and 1 were used as the values of baα and bcα, respectively [bakτ is the characteristic bond strength of the adhesive in MPa and bckτ is the characteristic bond strength of concrete according to:cf is the compressive strength of the concrete in MPa  and bckk  are the product-specific factors of the adhesive and concrete, respectively. In this study, a sysk value of 1 was used [cf was considered based on fib Model code 2010 [In this section, provisions of an existing methodology for predicting end debonding (letin 90  and Zilcletin 90 ) are comectively ,47. Finawas used ,47. The ode 2010 .yP, uP, and y,FRPε) were used to calculate the bond resistance of the CFRP-strengthened beams according to the following steps:y = PyLM1/2, where L1 is shear span of the beam. Step 1: calculate the moment capacity of the unstrengthened beam at the yielding point of the steel reinforcement: X from the beam support, where the FRP strip is first required for load-bearing purposes: X = 2y/PuM.Step 2: calculate the position of point act = εy,FRP EFRP AFRPF, where y,FRPε is the CFRP strain at a level of load equal to the yielding load of the control beam of the same group, and FRPE and FRPA are CFRP modulus of elasticity and CFRP area, respectively.Step 3: calculate the actual strip force at a point corresponding to the yielding load of the control beam: b = XL − a − 0.9d(cotθ − cotα)/2, where a is the distance between the support and end of the FRP strip, θ is the angle between the concrete compression strut and the beam axis perpendicular to the shear force, and α is the angle between the shear reinforcement and the beam axis perpendicular to the shear force. More information regarding to the “shift rule” can be found in Eurocode 2 [Step 4: calculate the available anchorage length considering the “shift rule”: rocode 2 .Step 5: calculate the design bond strength using Equation (2).Step 6: calculate the bond resistance of one CFRP strip using Equation (1) and multiply it by the number of CFRP strips.act/FfbdF). If this ratio is greater than one, the actual force in the NSM strip is larger than the bond capacity predicted by Equation (1), indicating that the beam will fail due to premature end debonding. On the contrary, if the aforementioned ratio is less than one, the bond capacity would exceed the actual force in the NSM strip, indicating that the design is conservative and no end debonding would occur.Step 7: calculate the ratio of actual strip force obtained from Step 3 to bond resistance obtained from Step 6  which means the anchorage length was sufficient to transfer the actual strip force without premature end debonding. Nevertheless, further increases in the testing temperature up to 70 °C, resulted in a large reduction in the material properties of the adhesive and, subsequently, to larger strains (and forces) in the CFRP strip, which resulted in ineffective bonds between the FRP strip and the adhesive, thus leading to end debonding. This was confirmed by experimental observation, as the beam tested at 70 °C failed by end debonding. Finally, according to analytical predictions for the specimen at 85 °C, an end debonding failure mode was expected but the beam eventually failed by concrete crushing . In view of these results, the comparison of analytical predictions and experimental results confirmed the accuracy of the proposed methodology. However, more experimental work is needed to evaluate the adequacy of the aforementioned formulation for higher testing temperatures. act/FfbdF ratio with respect to testing temperature is shown in gT of the epoxy adhesive. Once testing temperature approached the lower limit of the range of values for the gT, the ratio started to increase to a value near to 1 for testing temperatures close to the mid position of the range of values of gT . Finally, when the testing temperature overtook the upper limit of the range of values for gT, the act/FfbdF ratio rapidly increased. This demonstrates the effect of high service temperatures on the bond capacity of the adhesive joint, which, in the end, affects the failure mode of NSM CFRP-strengthened RC beams.The evolution of the gT of the epoxy adhesive), as this may affect the bond performance. In addition, concrete compressive strength is also an important parameter in the proposed methodology. Therefore, the expanded database should also include specimens with different ranges of concrete compressive strength.The analytical predictions on end debonding phenomena presented in gT.The obtained experimental results showed a good performance of the NSM technique to strengthen concrete structures for temperatures relatively close to the epoxy gT of the epoxy resulted in a reduction in beam capacity equal to 3.95% and 10.45% for beams SB2S-2-70 and SB2S-2-85, respectively.The capacity (ultimate load) of the strengthened specimens was not affected by testing temperatures equal to 40, 50, and 60 °C, whilst the application of testing temperatures higher than the gT of the epoxy) failed by FRP rupture, whilst the failure mode changed when the testing temperature was beyond the upper range of the gT of the epoxy adhesive . This is evidence of the effect of temperature on the performance of the adhesive and the bond resistance between the adhesive and concrete and, therefore, on the failure mode of the strengthened flexural element. In all groups of specimens, the control (unstrengthened) beams failed by concrete crushing after yielding of the steel reinforcement. The application of different testing temperatures showed that strengthened beams subjected to 20, 40, 50, and 60 °C (near and in the lower range of the Analytical predictions on premature end debonding were compared to the experimental results and good agreement was found, thus confirming the capability of the analytical procedure to predict end debonding failure.gT of the epoxy adhesive, showing that temperature can be a key factor if the gT of the epoxy adhesive is exceeded. The analytical procedure demonstrated that proneness to premature end debonding of the NSM joint is more pronounced for testing temperatures near the In this work, an experimental program designed to evaluate the effect of high service temperatures on the flexural performance of NSM CFRP-strengthened RC beams was presented. The results in terms of load–deflection curves and failure modes are presented and discussed. Furthermore, an analytical procedure in the literature ,47 was a


Since 2016, following the Italian “National Plan to Contrast Antimicrobial Resistance”, Campania Region has implemented an antimicrobial stewardship program, including the obligation to associate an appropriate International Classification of Diseases-9 code to each antibiotic prescription, the publication of schemes for empirical antibiotic therapy and educational interventions.To evaluate the impact of these interventions on the prescribing habits of family pediatricians, we conducted a retrospective cohort study (January 2016–December 2020), including all patients registered in an associate practice of Primary Care Pediatricians. We collected data on antibiotic prescriptions through a specific study management software; our primary outcomes were the annual prescription rates, calculated for both the number of patients in follow-up and the number of medical consultations, and the annual prescription rates for selected antibiotic classes and molecules. To investigate the hypothesis that chronic conditions would be associated with an increased rate of prescription, we also tested the association between underlying conditions and the number of antibiotics received.R2 = 0.927, p = 0.009), and the annual prescription rate per 100 medical consultations . The prescription rates of Amoxicillin-Clavulanate  and third generation Cephalosporins  significantly decreased; we didn't find significant modifications in the prescription rates of Amoxicillin and Quinolones; finally, we observed a trend toward reduction in the prescription of Macrolides. No statistical association was found between antibiotics prescribing frequency and history of chronic diseases.During the study period, 2,599 children received 11,364 antibiotic prescriptions . From 2016 to 2020 we observed a substantial reduction in both the annual prescription rate per 100 patients (9.33 to 3.39; Following the implementation of the regional interventions on antimicrobial stewardship, we observed a substantial reduction in the overall antibiotic prescription per patients and per medical consultations, with a statistically significant reduction in the use of broad-spectrum molecules. Considering the results of our analysis, new guidance and training interventions addressed to specialists in the primary care sector should be implemented to further limit antibiotic resistance. Antimicrobial Resistance (AMR) is still a matter of concern for health organizations worldwide, because of its burden both on public health and patients' management. Direct consequences of infections by multidrug resistant (MDR) pathogens include prolonged illness and hospital stay, increased complications and mortality, and loss of protection for a growing number of fragile patients. On a large scale this phenomenon is causing a relevant raise in healthcare expenditure for Western countries, directly involved in the selection of resistant strains, while developing countries are increasingly exposed to the risk of circulation of MDR bacterial species without having the possibility of acquiring new generation molecules .Despite the fact that an overall improvement has been reported in the last few years, data on antibiotic consumption and AMR in Italy are alarming. According to the European Surveillance of Antimicrobial Consumption Network (ESAC-Net), Italian quality indicators for antimicrobial prescription in the community are worse than the European average, including the consumption of antibiotics for systemic use, combination of Penicillin and Beta-lactamase inhibitor, third and fourth generation Cephalosporins and the ratio between the consumption of broad-spectrum and narrow-spectrum Penicillins, Cephalosporins and Macrolides . As a coGoossens et. al reported a high AMR rate in countries with high consumption of antibiotics . This asAMR rates are higher in Southern and Eastern Europe, where generally more antibiotics are consumed, than in Northern European countries , 6, 10. For all these reasons, in the past twenty years, antimicrobial stewardship programs have been implemented both at European, national, and regional level, in order to limit the number of inappropriate prescriptions. Although it is established that pediatric Antimicrobial Stewardship programs have a significant impact on the reduction of antibiotic use, healthcare costs, and antimicrobial resistance in both inpatient and outpatient settings, the most effective intervention in cutting antibiotic prescriptions is not yet clearly identified , 14.We hereby report the impact of a multifaceted intervention implemented at regional level on the prescribing habits of family pediatricians, which are a primary target of local antimicrobial stewardship programs.2, comprising some urban areas among those with the highest population density and the lowest-medium socioeconomic status in the metropolitan area.We conducted a retrospective open cohort study (January 2016–December 2020), including all patients aged 0–16 years registered in an associate practice of Primary Care Pediatricians (PCPs) located in a single Sanitary District in the province of Naples, the largest city in Southern Italy. The district accounts for about ninety thousand inhabitants and covers a surface of 17.45 KmThe associate practice taking part in the study is composed of three PCPs responsible for about three thousand patients living in the area. In the Italian healthcare system PCPs provide a first-line access for health issues to all children at no cost and drive patients to further access to care if needed. PCPs are in charge of the promotion of health, primary and secondary prevention, first approach to diagnosis and treatment of acute conditions and follow-up of patients with chronic diseases.Starting from 2016, the Campania Region endorsed the principles defined by the “National Plan to Contrast Antimicrobial Resistance” (PNCAR)  and starFirstly, all primary care physicians were asked to associate an appropriate International Classification of Diseases-9 (ICD-9) code to each antibiotic prescription . In 2017All pediatricians who took part in the present study participated in each phase of the program: acknowledged the obligation to associate diagnostic codes to antibiotic prescription, received the regional indications for empiric antibiotic treatment for the most common pediatric infections, and finally attended the online e-learning classes.The software Kappamed (version 12.4.30), routinary used by the study pediatricians to record and manage patients' personal details, medical history, diagnostic work-up and treatment, was used to retrospectively obtain data about antibiotic prescriptions. At the time of the first consultation with the pediatrician, a parent or legal guardian was asked to provide an informed consent to the processing of the patient's personal data, according to local procedures and to the Declaration of Helsinki. Although this analysis did not require a formal approval by the Ethical Committee, all data regarding antibiotic prescriptions by each pediatrician during the study period were extracted from the software and linked to an anonymous alphanumeric code for each patient. All the prescriptions were then merged into the same database and rearranged by the alphanumeric code in order to allocate multiple prescriptions to each patient during the follow-up period.The collected data included: patient's alphanumeric code, date of birth, gender, number of siblings, Body Mass Index (BMI), date of prescription, age at the time of the prescription, antibiotic class and molecule, single diagnosis and previous health problems encoded according to ICD-9.p-value of less than 0.05 was considered significant.Data are presented as mean ± standard deviation (SD), median and interquartile range (IQR) and proportions are expressed as percentage (%). The statistical analysis was performed using IBM SPSS Statistics, released 28.0.1.1. Categorical variables were compared using the Chi-2 test and Fisher's exact test. Continuous variables were compared using the unpaired Student's t-test or Mann Whitney, as appropriate. The variation of the rates during the study period was analyzed with a linear regression test. A Our primary outcome was the annual prescription rate calculated for both the number of patients in follow-up and the number of medical consultations per year. We used the number of medical consultations as a denominator in order to minimize the potential impact of COVID-19 pandemic, which could have resulted in a decrease in prescription rates, due to a limited access to medical care during the pandemic.As a secondary outcome we calculated the annual prescription rates and percentage of specific classes and molecules, focusing on the broad-spectrum antibiotics most widely prescribed.In addition, we compared the prescription of antibiotics in the four years before the beginning of the COVID-19 pandemic to the consumption reported in 2020, in order to estimate a possible change in prescription habits during pandemic. Specifically, we analyzed the prescription rates of Amoxicillin, Amoxicillin-Clavulanate, Clarithromycin, Azithromycin, third generation Cephalosporins and Quinolones.Access/Watch index. The latter is based on the AWaRe classification by the World Health Organization (WHO), that categorizes antibiotics in three groups according to the risk of AMR selection:Access, which includes antibiotics that have activity against a wide range of commonly encountered susceptible pathogens while showing lower resistance potential than antibiotics in the other groups. This group includes antibiotics that are recommended as essential first or second choice empiric treatment options.- Watch, which includes antibiotic classes that are at relatively high risk of selection of bacterial resistance. These medicines should be prioritized as key targets of stewardship programs and monitoring.- Reserve, which includes antibiotics that should be reserved for treatment of confirmed or suspected infections due to multidrug-resistant organisms.- Outpatients prescriptions recorded during the study period did not include antibiotics classified as Reserve, that are usually prescribed in inpatient setting, but only antibiotics classified as Access  and Watch  according to the AWaRe classification .Finally, we tested the association between the annual number of prescriptions received by each child and the presence of underlying chronic conditions, including risk factors for recurrent urinary tract infections (UTI) , overweight and obesity, asthma, prematurity, chronic tonsillar diseases, lymph-adenopathy, previous episodes of otitis media, bronchitis, pneumonia, autism and developmental delay. We investigated the association between these conditions and the possibility to receive a number of antibiotic prescriptions higher than median value.outliers. The presence of the health conditions above mentioned was investigated in these patients as well.Children who received a number of antibiotic prescriptions 3 or more IQR higher than the median were identified as Overall, 2,599 children  were included in the study. Only 458 (17.6%) had one or more siblings. Regarding underlying conditions and past medical history, 996 (38.4%) children were overweight or obese, 1,025 (39.4%) had previous episodes of respiratory tract infections, including otitis media, bronchitis and pneumonia and 59 (2.3%) had risk factors for recurrent UTI .R2 = 0.927, p = 0.009), and the annual prescription rate per 100 medical consultations   .Overall, 11,364 antibiotic prescriptions  were recorded in the 2,599 children. The distribution and characteristics of annual antibiotic prescriptions is reported in R2 = 0.995, p < 0.001). The prescription rate of Amoxicillin-Clavulanate also significantly decreased from 50.25 to 14.21   .R2 = 0.25, p = 0.391) and Quinolones  did not change during the study period and we observed a trend toward progressive reduction in the prescription of Macrolides, although the difference in rates was not statistically significant . As reported in p = 0.029).Prescription rates of Amoxicillin , with a parallel increase of Amoxicillin from 9.95% to 32.94% (p = 0.045). The consumption of third generation Cephalosporins expressed as a percentage of the total consumption of antibacterials for systemic use has been found to be reduced from 25.39% in 2016 to 13.36% in 2020 (p = 0.007). The consumption of fluoroquinolones and macrolides went respectively from 0.26% to 0.18% (p = 0.824) and from 37.17% to 25.07% (p = 0.429) of the total consumption.Regarding the analysis of relative antibiotic prescriptions, Amoxicillin-Clavulanate and third generation Cephalosporins were found significantly decreased, while non-significant variations were registered for the other broad-spectrum classes. The annual consumption of Amoxicillin-Clavulanate expressed as percentage of the total consumption of antibacterials for systemic use decreased from 44.90% to 34.95% (Access/Watch index increased from 1.17 (95%CI 0.700 to 1.648) to 2.00 (95%CI 1.464 to 2.542) after October 2018, following the spreading of the regional guidelines and the publication of an e-learning course  to 0.83 (95%CI 0.510 to 1.149) . Similarg course .p < 0.001).We observed a seasonal variation in the antibiotic prescription rate per 100 patients, with a significant increase of overall prescriptions in Winter season  or the history of a previous episode of otitis media (p = 0.013), bronchitis (p < 0.001) and pneumonia (p = 0.026) were associated with a higher prescription frequency than the median value.The median number of antibiotic prescriptions was 2 (IQR 3–1) per patient annually. The presence of any underlying medical condition was not associated with a higher probability of antibiotic prescription. However, the presence of risk factors for recurrent UTIs  in at least one of the years of observation were identified as “outliers”. Among them we found a relatively high proportion of overweight or obesity  that are the most frequent medical conditions beyond the history of previous infections.Patients who received more than 8 antibiotic prescriptions , asthma (p = 0.03) and autism (p = 0.005).In addition, we observed a significantly increased proportion of selected medical conditions in the group of outliers, including the presence of risk factors for recurrent UTIs /1,000 patients' days is the most widely accepted method of consumption monitoring in adult specialties. However, this is inaccurate for monitoring antibiotic consumption in pediatric age range. Until today, there is no consensus on the best approximation method to use in pediatrics: the monitoring of days of therapy (DOT) per 100 or 1,000 patient days seems to be suitable, since it is not biased by the body weight variability –31.Access/Watch antibiotics prescription index was registered since October 2018, according with a significant improvement of Amoxicillin/Amoxicillin-Clavulanate index since September 2018.For this reason and in line with most recent antibiotic reports in pediatrics , 23–25, We complied with ESAC guidelines to assess the second and the fourth clusters of indicators, finding respectively significant decrease in the relative consumption of Amoxicillin-Clavulanate and third generation Cephalosporins and the presence of seasonal variation in overall antibiotic prescribing.The reported change in the antibiotic prescription during the study period did not show significant harms in the study population. Although a retrospective analysis of the impact of the AMS interventions on the study population was not feasible, the pediatricians taking part in the study did not report a relevant difference in the access to Emergency Department or hospital admission during the five years of observations.Finally, an additional key determinant of antibiotic prescription is the lack of communication between healthcare workers and patient/caregivers, that leads to repeated medical consultations and eventually results in an inappropriate prescription to meet expectations, as emphasized by the European Center for Diseases Prevention and Control (ECDC) in an informative pamphlet addressed to PCPs –38. NeveAlthough we did not find a significant association between obesity and a high prescriptive frequency, within the outliers for number of prescriptions in a year obesity was among the most frequent conditions, together with previous episodes of respiratory tract infections –41.While the relationship between the antibiotic prescription and the ongoing illness is well studied, there is lack of evidence about the relationship between the antibiotic prescription frequency and the past medical history and chronic conditions of the patient.In our cohort, we did not observe a significant variation in antibiotic prescriptions attributable to COVID-19 pandemic. From March to May 2020, during the first lockdown, there was a reduction of medical consultations, which were partially replaced by telephone consultations and other forms of telemedicine mainly for children with SARS-CoV-2 infections or other mild forms of respiratory illnesses. This, along with the first schemes proposed for COVID-19 treatment, could result in a possible increase in prescription of broad-spectrum molecules. To limit this effect, we standardized the prescription rates of our cohort either for 100 patients in follow-up or for 100 medical visits, but even with this approach we did not observe a change in the trend toward reduction of prescription started in 2018.Although a large increase in the consumption of macrolides  with limited evidence of efficacy , 43 has Some studies speculate that a similar effect could be explained by the rising use of remote medical consultations, registering variations in prescriptive frequency based on different socio-economic settings .Due to limitations in the data deductible from the practice management software, we analyzed the prescription rate instead of the days of therapy (DOT), which is more widely accepted as a method of quantification of antibiotic prescriptions in children –31. NeveFor the same reason we couldn't analyze factors related to the patient's clinical examination at the time of the prescription. As observed by O'Brien et al.  some cliThe data reported in the present study focused on the impact that the regional interventions had in a cohort of PCPs and do not apply to inpatient settings. A new version of the regional guidelines for empiric antibiotic prescription specifically addressed to hospital practitioners is going to be implemented at the end of the year. We believe that only a parallel implementation of AMS interventions, both in the outpatient and inpatient setting, could effectively impact on prescription habits and local AMR.Finally, we believe that a longer follow-up period after implementation of AMS interventions could help to better understand not only their efficacy, but also their duration over time, and potentially to plan a catch-up intervention.Antimicrobial resistance is an actual and challenging issue in pediatric healthcare.Monitoring the consumption of antibiotics and the impact of antimicrobial stewardship policies is mandatory. In the light of a high geographical variability of AMR rates, local health policies and training programs should be promoted and tailored at local level. Additional steps for implementation should include: disseminating similar interventions to health-care practitioners working both in inpatient and outpatient settings, planning catch-up training programs to reinforce the adherence to national and local guidelines. Further research is required to understand the patients-related factors linked to a high frequency of prescriptions in order to better address these interventions.


Minoritized populations experience increased risk of antimicrobial resistant infections in the community and are subjected to further risk of infections because of mass incarceration. At highest risk for infections are criminal-legal involved older adults, who experience increased social vulnerability and are often high users of medical care. Antimicrobial stewardship is recommended by the IDSA to reduce unnecessary or suboptimal antibiotic use but is rarely implemented in carceral settings. The defined daily dose (DDD) per 1000 patient days is a frequently used metric of calculating antibiotic prescriptions that can be used to benchmark and track impact of interventions. The goal of this research was to apply the DDD metric as related to 1000 jail inhabitants to 2021 antibiotics prescribing in Massachusetts jails.After receiving approval from the Massachusetts Sheriffs Association, we requested de-identified antibiotics prescription records from the State Office of Pharmaceutical Services for 2021. We followed the World Health Organization guidance for DDD calculation. We grouped antibiotics into 7 categories. We estimated the yearly number of people incarcerated by monthly capacity and the average length of incarceration.We found heterogeneity in antibiotic use patterns at the jails . Certain jails  were high users of antibiotics, while other jails  were low users. We also found significant heterogeneity in the classes of antibiotics used across the jails. Certain jails appear to prefer cephalosporins  while others  frequently use fluoroquinolones.Applying the DDD metric is feasible in the novel setting of jails and may be utilized to benchmark antibiotic usage. This proof of concept can inform future antimicrobial stewardship interventions in carceral settings.Tara Bylsma, MD, Takeda Pharmaceuticals: My husband was employed by Takeda June-Aug 2021 as a summer MBA intern Shira Doron, MD, Sunovion: Advisor/Consultant.


In Germany, overprescribing of clindamycin was noteworthy in the past. Therefore, the aim of our study was to determine the trend of antibiotic prescriptions in primary dental care. (2) Methods: Prescriptions of antibiotics in German primary dental care from 2017 to 2021 were analysed using dispensing data from community pharmacies, claimed to the statutory health insurance (SHI) funds, and compared with all antibiotic prescriptions in primary care. Prescriptions were analysed based on defined daily doses per 1000 SHI-insured persons per day (DID). (3) Results: Amoxicillin was the most frequently prescribed antibiotic  in primary dental care, followed by clindamycin . Dental prescriptions still made up 56% of all clindamycin prescriptions in primary care in 2021. (4) Conclusions: Our study suggests that the problem of overuse of clindamycin in German dentistry has improved, but still persists. Antimicrobial resistance, driven by misuse and overuse of antibiotics, is a major and global public health challenge . TherefoThe consumption of antibacterials for systemic use is substantially higher in the community compared to the hospital sector. Ninety one percent of antibacterial use, reported by the European Union (EU) Member States and European Economic Area (EEA) countries for 2020, occurred in the community . Dental Selection of the appropriate antibiotic appears to be another issue in dentistry where there is potential for improvement ,10,11,12In Germany, data are scarce on the outpatient prescription of antibiotic agents by dentists and current figures are lacking ,11,12. TDental prescriptions of systemic antibiotics in primary care remained stable over the period 2017 to 2021 (1.20–1.25 DID). Dental prescriptions as a percentage of all antibiotic prescriptions increased from 10% to 15% during this period. The most commonly dispensed antibiotics in 2021 were amoxicillin , clindamycin , amoxicillin and beta-lactamase inhibitor , phenoxymethylpenicillin , doxycycline , cefuroxime , and metronidazole . Prescriptions of clindamycin declined by 21% over the period, from 0.37 DID in 2017 to 0.29 in 2021. Prescriptions of phenoxymethylpenicillin also decreased . In contrast, the share of prescriptions of amoxicillin without a beta-lactamase inhibitor  and with a beta-lactamase inhibitor  increased .All prescriptions of systemic antibiotics in primary care decreased by –36%, from 12.59 DID in 2017 to 8.06 in 2021. Prescriptions of amoxicillin , and doxycycline  decreased at about the same rate as all prescriptions. There was a particularly sharp decrease in prescriptions of phenoxymethylpenicillin  and cefuroxime , and a smaller decrease in clindamycin prescriptions . In contrast, prescriptions of amoxicillin in combination with a beta-lactamase inhibitor  increased .The monthly mean (± standard deviation) DID of dental prescriptions during the period was 1.20 ± 0.07. Monthly values were 1.17 in January 2017, and 1.31 in December 2021, and they ranged between 1.03 and 1.36. Thus, they were not subject to large fluctuations. Before the start of the COVID-19 pandemic, DID of all antibiotics showed typical seasonal fluctuations with high values during winter months and low values during summer months. In the period from January 2017 to March 2020, values ranged between 8.92 and 17.93 DID (mean 11.99 ± 2.27). From April 2020 to December 2021, they ranged between 6.32 and 10.86 DID (mean 7.84 ± 1.16) .Prescriptions of clindamycin by dentists decreased from 0.37 DID  in 2017 to 0.29 DID (24% share) in 2021 . All cliDental prescriptions make up a substantial proportion of all antibiotics prescribed in primary care. The share of antibiotics dispensed in dental prescriptions increased from 10% to 15% for the period 2017–2021, mainly due to a decrease in all antibiotic prescriptions in primary care. This decrease in antibiotic use could be explained, in part, by decreased prescriptions for respiratory diseases for children . A sharpIn order to assess whether there could have been potential for savings in dental prescriptions, one would need to estimate whether there were non-indexed prescriptions and what the proportion of them might have been. A study in the United Kingdom has shown that only 19% of antibiotic prescribing in general dental practice in 2016 was carried out according to guidelines . StudiesVery few comprehensive studies exist on the antibiotic prescribing behaviour of German dentists . An educStreptococcus spp. and Staphylococcus spp. and that clindamycin had comparatively high resistance rates regarding these (17–19%) [Clostridium difficile infection, occurred more frequently with this antibiotic [The focus of antibiotic therapy for odontogenic infections is to use the most effective and safe substance ,9. Data 17–19%) . Penicil(17–19%) . Gastroi(17–19%) ,32,33,34tibiotic ,35. Ther–19% . Petibiotic .Past studies revealed overprescribing of clindamycin in German dental care and markedly higher use of this antibiotic compared to other European countries, such as England, Scotland, Norway and Sweden ,12. Our The Federal Joint Committee (G-BA), the highest decision-making body of the joint self-government of physicians, dentists, hospitals and health insurance funds in Germany, issues directives for the benefit catalogue of the SHI funds and, thus, specifies which services in medical care are reimbursed. The G-BA has planned a new guideline on antibiotic care in dentistry for 2023. As one aspect of the guideline, recommendations are planned for the prescription of clindamycin. For this purpose, the German Dental Association (BZÄK) works in an advisory capacity to the G-BA working group for the quality assurance procedures for systemic antibiotic therapy in dental treatment . We hopeThe overall balance in the trend of prescriptions was mainly caused by a decrease in prescriptions for the antibiotics clindamycin (−0.08 DID), phenoxymethylpenicillin (−0.04 DID), doxycycline (−0.01 DID) and cefuroxime (−0.01 DID), and an increase in prescriptions for amoxicillin, both without (+0.12 DID) and with a beta-lactamase inhibitor (+0.06 DID).The aminopenicillin amoxicillin is effective as a broad-spectrum antibiotic against both Gram-positive and Gram-negative bacteria and is recommended as a first-line antibiotic, according to the German dentistry guideline . The narClostridium difficile infections [Cefuroxime is still prescribed too frequently in primary care in Germany although this antibiotic is on the World Health Organization’s ‘watch group antibiotics’ list ,46,47. Afections ,48. The fections . In Belgfections ,6.The decline in prescriptions of doxycycline might also be related to a high rate of resistance to this antibiotic ,50. In BThe increase in prescriptions of amoxicillin with a beta-lactamase inhibitor should be viewed critically. Increased use of this combination carries the risk of antimicrobial resistance . In addiThe major strength of this study is that it was based on dispensing data from the vast majority of community pharmacies in all federal states of Germany and, thus, was a highly representative sample, representing 88% of Germany’s population. Only data from privately insured patients and for services not charged to the SHI system were not available in the database. The proportion of privately insured persons in Germany averaged 11% during the analysis period . AnotherA limitation is that neither patient data nor data on indication e.g., type of odontogenic infection, were available in our database. Therefore, we could not evaluate the quality of dental antibiotic prescribing, in general, or the appropriateness of the use of clindamycin, in particular. Furthermore, the use of DID to measure antibiotic prescribing may be unsuitable for drugs used in children, because in this patient group dosing can be very different from that for adults.We conducted a longitudinal drug utilization study in the period 2017–2021, querying the database of the German Institute for Drug Use Evaluation (DAPI) . This daDental prescriptions could be differentiated in the database from medical antibiotic prescriptions in primary care by different identification features of the prescriptions. In the group “All prescriptions” dental and medical prescriptions were included.Dispensing data were linked to a database containing information on the name, composition, active ingredients, package size, dosage form, and route of administration using the specific product code . We classified antibiotics according to the official version of the Anatomical Therapeutic Chemical (ATC) classification system of the World Health Organization Collaborating Centre for Drug Statistics Methodology . DefinedAntibiotic use was estimated by defined daily doses per 1000 SHI-insured persons per day (DID) on an annual and monthly basis . The numAntibiotic prescriptions by dentists in Germany from 2017 to 2021 were analysed and compared with all antibiotic prescriptions in primary care. The substances amoxicillin, clindamycin, amoxicillin and beta-lactamase inhibitor, phenoxymethylpenicillin, doxycycline, cefuroxime, and metronidazole, prescriptions of each of which accounted for ≥1% of DID of all dental antibiotic prescriptions, were selected for analysis per year. In order to check for potential influences of the COVID-19 pandemic, dental and all antibiotic prescriptions in primary care were also subjected to a detailed analysis per month.An increasing proportion of antibiotic prescriptions in German primary dental care are beta-lactam antibiotics, in accordance with the first line recommendations of the German dentistry guidelines for many odontogenic infections. The downward trend in dental clindamycin prescriptions in recent years is encouraging. Nevertheless, it should be noted that the use of this antibiotic is still very high in Germany, compared to other European countries. However, since no information on patient characteristics, including diagnoses, was available in the database used, it must be taken into account that specific reasons and potential interventions for reducing dental antibiotic prescriptions remain to be explored. Hence, further studies are needed to shed light on this.