This study aimed to assess the feasibility of utilizing geopolymer for repairing reinforced concrete beams. Three types of beam specimens were fabricated: benchmark specimens without any grooves, rectangular-grooved beams, and square-grooved beams. The repair materials employed included geopolymer material, and epoxy resin mortar, while carbon fiber sheets were used as reinforcement in select cases. The repair materials were applied to the rectangular and square-grooved specimens, with the carbon fiber sheets attached to the tension side of the specimens. To evaluate the flexural strength of the concrete specimens, a third-point loading test was conducted. The test results indicated that the geopolymer exhibited higher compressive strength and shrinkage rate compared to the epoxy resin mortar. Furthermore, the specimens reinforced with carbon fiber sheets demonstrated even greater strength than the benchmark specimens. In terms of flexural strength under cyclic third-point loading tests, the carbon fiber-reinforced specimens exhibited the ability to withstand over 200 cycles of repeated loading at 0.8 times the ultimate load. In contrast, the benchmark specimens could only withstand seven cycles. These findings highlight that the use of carbon fiber sheets not only enhances compressive strength but also improves resistance to cyclic loading. Civil engineers are increasingly faced with the challenge of improving the performance of existing structures, aiming to extend their service life by restoring their mechanical strengths and enhancing their strength beyond their original levels. Many of these structures were designed according to regulations and requirements that are no longer up to date, failing to meet the standards of modern buildings. Exposure to natural forces, human activities, or the effects of time can result in cracks, erosion, or damage. Repairing and reinforcing these aging structures presents a more cost-effective approach compared to redevelopment, as it reduces resource consumption and minimizes the environmental impact associated with new construction.Given that the majority of these buildings do not meet the design requirements stipulated by current regulations, it becomes essential to carry out necessary repairs and reinforcement engineering to ensure the continued use of the building, especially when partial structural damage occurs, without compromising the overall structural integrity. Consequently, retrofitting reinforced concrete structures remains a critical and pressing issue.Generally, when reinforced concrete (RC) structures experience crack formation due to external forces, reinforcement is typically carried out considering the crack size and location. Often, cracks tend to occur at locations subjected to significant structural loading, such as the maximum bending point in a reinforced concrete beam. Prior to implementing reinforcement measures, thorough observations are conducted to assess the depth of the cracks, determining whether steel repair is necessary prior to material restoration. During the repair process, various methods are employed depending on the specific structural elements involved. Previous research studies have demonstrated the efficacy of utilizing different types of repair materials, such as alkali-activated slurry and high-performance fiber cement, to effectively enhance the flexural strength of the structure ,4,5,6,7.Although the utilization of repair materials for the inclined surface of a concrete beam can improve its flexural strength, the degree of enhancement remains limited. To achieve significant improvements in bending strength, the retrofitting of high-polymer composite materials has been explored ,9,10,11.To replicate deteriorated concrete slabs, a previous study employed concrete slabs with deliberately introduced notches . By incoAs previously mentioned, the application of carbon fiber sheets has been proven to enhance the flexural strength of specimens. Several studies have indicated that the use of carbon fiber sheets not only improves flexural strength but also enhances impact resistance and fatigue resistance of the specimens ,28. FurtGeopolymer material presents a range of benefits in scientific and technical contexts. Notably, it exhibits an environmentally friendly composition that diminishes reliance on natural resources and promotes the recycling of industrial waste. Moreover, geopolymer material possesses a reduced carbon footprint, improved durability, and exceptional versatility, enabling customization to suit particular application needs ,31,32. IThe objective of this study is to investigate the potential for achieving complete restoration of the original strength in damaged concrete sections by employing geopolymer as a repair material. Specifically, this research focuses on assessing the feasibility of replacing traditional epoxy resin mortar with geopolymer material for repairing inclined surfaces. Furthermore, the research aims to evaluate the performance of retrofitting grooved concrete specimens using carbon fiber sheets. To achieve these goals, the compressive strength and shrinkage of the two repair materials were measured following ASTM C109  and ASTMEpoxy resin is a thermosetting material commonly used as an adhesive and coating. It is most commonly produced by the reaction of epichlorohydrin and phenoxyethanol. In this study, the epoxy resin A and resin B (SB-LEM) were provided by SamBond International Co., Taipei, Taiwan, which were blended in a fixed ratio of 2:1. This particular resin sand mixture exhibits favorable properties, such as lightweight nature and high adhesion. Epoxy resin sand mixtures are commonly utilized for inclined surface repairs due to their excellent weather resistance and ability to mitigate the corrosion impact on steel reinforcement during crack repairs. The resin sand mixture employed in this research is specifically designed for construction joints and overhead repairs, and it adheres to a predefined proportioning scheme.Geopolymer materials are non-crystalline or semi-crystalline substances commonly derived from raw materials abundant in silicon or aluminum, such as metakaolin, coal fly ash, or ground-granulated blast-furnace slag powder. The production of geopolymer involves mixing the raw materials with an alkaline solution, which reacts with the particle surfaces of the raw materials, dissolving silica gel and aluminum gel ,40. ThisThis study used a carbon fiber sheet infused with epoxy resin, which was attached to the overhead surface of the concrete specimens. This material was provided by Sheng Peng Applied Materials Co., Ltd. . The material specifications are shown in The experimental plan encompassed a comprehensive series of tests, including assessments of material shrinkage, material compressive strength, third-point loading, and cyclic third-point loading. Through the analysis of material shrinkage and compressive strength test results, an optimized design proportion was determined by blending dry sand with the geopolymer material. The aim was to achieve a design proportion that would demonstrate a satisfactory level of compressive strength while exhibiting a minimal shrinkage rate. This specific design proportion was subsequently employed to evaluate the performance of the geopolymer material under third-point loading and cyclic third-point loading conditions.The nomenclature assigned to the specimens used in the material property tests is as follows: “E” denotes epoxy resin mortar, “G” represents geopolymer material, and “S” indicates the addition of dry sand to the geopolymer material. The specific quantity of dry sand incorporated into the geopolymer material is indicated by the value following the symbol “S”. For instance, if the geopolymer material was blended with 150% dry sand, the corresponding specimen would be labeled as “G-S150”, as shown in The shrinkage rate is a critical parameter to consider when evaluating repair materials. In the case of geopolymers, the loss of residual moisture occurs upon contact with the air surface following the complete reaction of alkaline liquid and slag. This phenomenon results in shrinkage. If shrinkage occurs on the underside of the repaired area, it can lead to the formation of cracks between the repair material and the substrate. These cracks may cause the repair material to detach or create pathways for water infiltration, thereby compromising the effectiveness of the repair. To gain insights into the shrinkage behavior of geopolymers and epoxy resin mortar, this experiment was conducted. Following the guidelines outlined in ASTM C490/C490M-21 , specimeGeopolymer materials exhibit cement-like properties, and the repaired surface is typically subjected to tensile stress. It is worth noting that the tensile strength of cement is approximately one-tenth of its compressive strength. To gain a comprehensive understanding of the properties of geopolymer and epoxy resin mortar, compressive tests were conducted in accordance with the guidelines specified in ASTM C109/C109M-21 . The repTo investigate the compressive strength of the geopolymer material with varying proportions of dry sand, additional compressive tests were performed. Specifically, materials incorporating 150% and 200% weight ratios of sand to geopolymer material were prepared. After a curing period of seven days, these specimens were subjected to compressive testing using a universal testing machine, following the standards outlined in ASTM C109/C109M-21 . The comIn this subsection, unidirectional reinforced concrete slabs were specifically designed and subjected to third-point loading tests. The design process entailed creating grooves of varying sizes on the slabs to simulate concrete cracks, which were subsequently repaired. Some of the test specimens were further reinforced by incorporating carbon fiber sheets in addition to the repair materials used to fill the grooves. The study aims to compare the bending strength of all the specimens after the repair and reinforcement processes.The design of the unidirectional reinforced concrete slabs in this subsection adheres to the guidelines specified in ACI-318-05. Specifically, #3 mesh reinforcing steel was employed and positioned 3 cm above the tensile side of the test specimens. The slabs were cast using a wooden mold, and the concrete utilized had an average strength of 21 MPa.This study involved the fabrication of three distinct types of unidirectional reinforced concrete slabs, which were subsequently further categorized. Each unidirectional reinforced concrete slab had dimensions of 120 cm × 36 cm × 7 cm, as shown in The concrete slabs with grooves, namely the R slabs and S slabs, were further divided into three subgroups: (1) without any repair, (2) repaired with geopolymer (referred to as G), and (3) repaired with epoxy resin mortar (referred to as E). Additionally, within the subgroups involving repair, certain specimens were reinforced with carbon fiber sheets (referred to as C). The nomenclature for the concrete slab specimens can be found in The experimental setup and equipment utilized in this study were identical to those employed in the third-point loading test. The objective of this experiment was to subject the test specimens to cyclic third-point loading until they reached their ultimate strength and experienced failure. The ultimate strength of each specimen was then recorded. Subsequently, specimens of the same type were subjected to loading at 0.7, 0.8, and 0.9 times their ultimate strength, and the loading process was repeated until failure occurred. The number of cycles required for failure was documented to assess the fatigue properties of the specimens under cyclic third-point loading.Each test specimen was divided into ultimate strength categories of 0.7, 0.8, and 0.9 times their ultimate strength. Consequently, each type of specimen consisted of four specimens: one for determining the ultimate loading strength and three for conducting cyclic third-point loading tests. The purpose of these tests was to evaluate the performance of each repair material in reinforced concrete slabs subjected to cyclic third-point loading following repair. The naming convention for the cyclic third-point loading specimens followed a similar format to that of the third-point loading test, with the addition of a prefix “C” to indicate the specimens underwent cyclic loading. Furthermore, a suffix “P” was added after the loading ratio  to denote that the specimens were subjected to loading at a ratio of their ultimate strength. For example, the designation “S-E-C-0.9P” referred to a square-grooved specimen repaired with epoxy sand mortar, reinforced with a carbon fiber sheet, and subjected to cyclic third-point loading at 0.9 times its ultimate loading strength.To provide a comprehensive description of the specimen production process for the third-point loading and cyclic third-point loading tests, the fabrication method is categorized into two sections: specimen fabrication and specimen repair and reinforcement. This division allows for a detailed explanation of the procedures involved in each stage.The fabrication process of a unidirectional reinforced concrete specimen involved the assembly of a wooden mold on-site, followed by the sequential placement of polystyrene boards to create the desired groove size. Subsequently, #3 steel mesh was positioned within the mold before pouring the concrete, as depicted in The assembled mold was placed on a flat surface for casting. To maintain the strength stability for each reinforced concrete specimen, on-site concrete quality control tests, including chlorides test and slump test, were performed in conjunction with quality control personnel during casting. To maintain a flat surface of the specimens, tamping, compaction tools, and trowels were used for compaction and smoothing.After the concrete casting was completed, a curing method was performed, and after 21 days of solidification, repair materials were cast, and reinforcement materials were attached. The compressive strength of the concrete cylindrical specimens was performed on the same day as the third-point loading test for each group of specimens to confirm the quality of concrete in each test.Before applying the repair material, a primer resin (EP 220) provided by Kuosen Enterprise Co., Ltd., Taoyuan, Taiwan, was used as the bonding material. A primer resin adhesive agent was used for each repair specimen before repairing with the repair material. This section is divided into compressive tests and shrinkage tests of repair materials. The ratio of geopolymer repair material used in the later third-point loading test was determined by the results of this section.The test results were recorded in accordance with the guidelines outlined in ASTM C490/C490M-21 . FollowiThe summarized average values of the shrinkage test results for all repair materials are presented in The results obtained from the shrinkage test, as presented in The compressive strength of the repair materials was determined through compressive tests conducted in accordance with ASTM C109/C109M-21 . The aveThe results of the compressive strength test, as presented in To evaluate the effectiveness of geopolymer and carbon fiber sheets for repairing surfaces at inclined positions, specimen G-S150 was selected as the repair material for the third-point loading and cyclic third-point loading tests. This decision was based on its high compressive strength and low shrinkage rate within the geopolymer material category. Consequently, all subsequent geopolymer material repaired specimens incorporated a weight proportion of 150% dry sand. For example, the specimen “R-G-C” denoted a rectangular-grooved specimen repaired with geopolymer material mixed with a weight proportion of 150% dry sand and reinforced with a carbon fiber sheet.To compare the feasibility of repairing damaged surfaces using geopolymer, this research employed epoxy resin mortar as the control group and geopolymer as the experimental group. Both groups were reinforced with carbon fiber sheets. The repair process primarily involved the application of geopolymer and epoxy resin mortar, respectively, while the carbon fiber sheets provided additional reinforcement.This section classified the specimens into two distinct sets: one comprising specimens with rectangular grooves (designated as specimen set R) and the other consisting of specimens with square grooves (designated as specimen set S). Each set comprised two individual specimens, upon which third-point loading tests were conducted. The resulting test outcomes, including failure modes, were meticulously documented for analysis and evaluation.The average flexural strength of specimens with rectangular grooves was plotted in the bar chart in From the analysis of The examination of In this subsection involving square-grooved specimens, the results of the third-point loading test exhibited similarities to those observed in the previous subsection. The repair of damaged concrete slab specimens (S) using either epoxy resin mortar or geopolymer material mixed with 150% dry sand had a limited effect on enhancing their flexural strength, resulting in less than a 5% improvement. However, the introduction of carbon fiber sheet reinforcement to the repaired specimens yielded significant enhancements. Irrespective of the repair material utilized, the flexural strength of the carbon fiber sheet-reinforced specimens exhibited a remarkable increase of 350% to 380% compared to the unrepaired specimens. Furthermore, the flexural strength of the carbon fiber sheet-reinforced repaired specimens surpassed that of the undamaged concrete slab (specimen B) by 160% to 180%.This section presents the findings of the cyclic third-point loading tests, categorized into two groups: rectangular-grooved specimens and square-grooved specimens. Prior to conducting the cyclic third-point loading test, one cylindrical specimen from each group underwent a compression test to ensure consistent concrete quality throughout the experiment. Subsequently, another specimen from each group was subjected to a flexural test to determine the ultimate flexural strength of the respective group. The remaining specimens in each group were then subjected to cyclic loading tests at varying ratios of their ultimate flexural strength.The findings presented in The findings derived from the cyclic third-point loading test on square-grooved specimens clearly demonstrate that the incorporation of carbon fiber sheet reinforcement enhances the fatigue resistance of specimens under tensile stress. Prior to the application of carbon fiber sheet reinforcement, the square-grooved specimen could only withstand 32 repeated loads at 14.4 kN. However, after reinforcement, the specimen exhibited the ability to endure over 1000 repeated loads at 40 kN.The fatigue resistance of specimens repaired with geopolymer material during the cyclic third-point loading test surpassed that of specimens repaired with epoxy resin mortar. This observation aligns with the outcomes of the third-point loading test, which revealed that specimens repaired with geopolymer material exhibited greater strength compared to those repaired with epoxy resin mortar. A similar trend was also evident in the results of the cyclic third-point loading test conducted using carbon fiber reinforcement.Despite a slightly higher shrinkage rate, the inclusion of geopolymer material with dry sand proves to be a viable alternative to epoxy resin mortar as a repair material. This alternative possesses superior material strength and leads to increased compressive strength in the concrete slab.The incorporation of sand in geopolymer materials leads to a decrease in shrinkage. Specifically, the shrinkage values decreased from 3.718 mm to 0.845 mm as the amount of sand increased.The addition of sand to geopolymer materials can enhance their compressive strength; however, there exists a threshold beyond which excessive sand content can result in a decline in strength.The findings obtained from the third-point loading test indicate that the repair of damaged concrete slabs using either epoxy resin mortar or geopolymer materials alone yields only marginal improvements in flexural strength. Moreover, the original undamaged strength of the slabs cannot be fully restored through these repair methods.When repaired concrete slabs are reinforced with carbon fiber sheets, their flexural strength can increase by 160% to 180% in comparison to undamaged concrete slabs.The results of the cyclic third-point loading test clearly demonstrate that the utilization of carbon fiber sheet reinforcement significantly enhances the fatigue resistance of concrete slabs.Based on the aforementioned conclusions, it is recommended to both repair and reinforce damaged concrete slabs to extend their service life. Repairing primarily contributes to restoring the shape of the slabs, while reinforcement elevates their flexural strength, surpassing even the pre-damaged state.The objective of this study was to investigate the viability of utilizing geopolymer materials for the repair of reinforced concrete beams. The research yielded the following conclusions:


One hundred and sixty-eight individuals (28.7%) were admitted to the hospital. Lower age, higher heart rate, and lower SpO2 were associated with an increased risk of hospitalization. Antibiotics were prescribed to 495 (84.8%) patients. According to the multivariate logistic regression, the diagnosis and duration of fever were substantially linked with antibiotic prescription. Conclusions: The present study reports real-life data about our PED experience. A high rate of antibiotic prescription was noted. In the future, it is necessary to improve antibiotic stewardship programs to increase clinical adherence to guidelines.Background: Lower respiratory tract infections (LRTIs) and community-acquired pneumonia (CAP) are among the most frequent reasons for referrals to the pediatric emergency department (PED). The aim of this study is to describe the management of antibiotic prescription in febrile children with LRTI or CAP admitted to a third-level PED and to investigate the different variables that can guide physicians in this decision-making. Methods: This is an observational, retrospective, monocentric study including patients < 14 years old who were presented to the PED for a febrile LRTI or CAP during the first six months of the year 2017. Demographic and clinical data, PED examinations, recommended therapy, and discharge modality were considered. Two multivariate logistic regression analyses were performed on patients with complete profiles to investigate the impact of demographic, laboratory, and clinical variables on antibiotic prescription and hospital admission. Results: This study included 584 patients with LRTI ( Lower respiratory tract infections (LRTIs) are among the most common reasons for pediatric emergency department (PED) visits . Among LAntibiotic resistance is an increasingly serious public health problem; a clear relationship was observed between primary care antibiotic prescribing  and antibiotic resistance .With regard to resistance patterns in the pediatric population in Italy, the 2020 Emilia-Romagna regional report showed a rate of resistance to amoxicillin for Streptococcus pneumoniae equal to 8.3% . MoreoveAll physicians should always follow guidelines when selecting whether and which antibiotics to administer ,13. For S. pneumoniae, are identified as responsible for CAP as children get older [S. pneumoniae CAP. Macrolides should be given to school-age children and adolescents with CAP due to atypical bacteria [Bacteria, particularly et older ,16,17. Abacteria . It is sbacteria .The aim of this study is to describe the management of antibiotic prescription in children with LRTI admitted to a third-level PED and to investigate the different variables that can help physicians make these decisions.This is an observational, retrospective, monocentric study including patients younger than 14 years of age who were referred to the PED of the IRCCS—AOU Policlinico di S.Orsola, Bologna , between 1 January 2017 and 30 June 2017. Inclusion criteria were: (1) body temperature > 37.5 °C (measured at the PED or reported by parents); and (2) diagnosis of LRTI or CAP defined at discharge. We considered the aforementioned fever threshold to keep the sample more homogeneous.Our center is an urban, academic, tertiary care facility, consisting of a PED with approximately 24,000 visits per year of children aged 0–14, a short-stay observation unit with 6 beds, and a ward with 28 beds. Patients referred to the PED are registered by a triage-qualified nurse; two more nurses are available for the PED and one for the short-stay observation patients. The medical visit is performed by both one or more pediatric residents and the attending physician. For each patient, a record form is filled in by the nurse and medical staff, including demographic data, anamnestic information, vital signs, physical examination, any performed treatments, subsequent clinical reevaluations, diagnosis, discharge modality (home or admission to the ward), and home therapy prescription when applicable. For children requiring a short-stay observation, prescribed examinations, therapy, and subsequent reevaluations are also noted on the same form.The diagnoses of LRTI or CAP defined at discharge were made considering clinical criteria used in daily practice. LRTIs included bronchiolitis, defined as an acute infection of the lower airways affecting infants under two years of age and characterized by respiratory distress, persistent cough, and wheezing or crackles on auscultation of the chest (or both); and bronchitis, defined as a self-limiting inflammation of the trachea and bronchi characterized by a persistent cough. CAP was defined as the presence of signs and symptoms of pneumonia including fever > 38.5 °C associated with chest recessions, new onset of cough, chest pain, and a raised respiratory rate in a previously healthy child due to an infection acquired outside the hospital.The study staff reviewed the medical records to collect demographic and clinical data , investigations performed in the PED (laboratory tests and/or chest X-ray), outcomes , and prescribed antibiotic therapy , which included the type of molecule, the relative dose in mg/kg/day, the number of daily administrations, and the days of treatment duration.Patients with incomplete medical records that did not allow for the confirmation of a diagnosis of LRTI or CAP, as well as those who were discharged from the PED against medical advice before completing the evaluation were excluded .T-Test or Mann–Whitney test, respectively. Finally, we performed logistic regression analysis to assess the impact of demographic, laboratory, and clinical factors on antibiotic prescription. To eliminate confounding effects, all independent variables with a statistically significant impact on the dependent variable were suddenly included in a multivariate logistic regression. Similarly, univariate and multivariate logistic regressions with hospital admission as the dependent variable were carried out. p values < 0.05 were considered statistically significant. The Statistical Package for the Social Sciences (SPSS-version 17.0) software was used for the analysis of data. The data was collected anonymously as part of a clinical audit carried out in the interest of improving the quality of health care, in agreement with the representatives of the referenced health facility; therefore, it was not submitted to the opinion of the Ethics Committee.Parametric continuous variables were reported as means and standard deviation (SD). Nonparametric continuous variables were expressed as the median and interquartile range (IQR). Categorical variables were expressed as numbers and relative percentages. Patients were compared according to their diagnostic class (LRTI or CAP) and whether they were admitted to the hospital or discharged from the PED. Pearson’s 𝛘2 test was used to compare the qualitative variables. Kolmogorov–Smirnov was used to assess the quantitative variables for normal distribution. Parametric and nonparametric variables were compared using the n = 368, 63%) or CAP  out of 3160 patients assessed in our PED for a febrile illness throughout the study period. A hundred and sixty-eight (28.7%) patients were hospitalized. We enrolled 584 patients with a diagnosis of LRTI  of 584 participants diagnosed with LRTI or CAP received an antibiotic prescription. We evaluated antibiotic prescriptions in the different age groups , in patients with LRTI or CAP, and in patients discharged home or hospitalized. We also investigated the type of antibiotic prescribed in the general population and in different patient groups . p-value 0.002), peripheral oxygen saturation < 92% , age 2–5 years , age > 5 years , as reported in Multivariate logistic regression analysis, performed considering hospital admission, showed a statistically significant correlation between hospital admission and the following variables: heart rate > 160 bpm  and >3 days of fever  were significantly correlated to any antibiotic prescription in the multivariate logistic regression analysis  of the patients discharged home ,21.Nowadays, one of the main challenges in pediatrics is to recognize which patients will benefit from antibiotic treatment and those who will not; thus, it is critical to understand what factors influence antibiotic prescription. We attempted to investigate demographic, clinical, and laboratory drivers of antibiotic prescription in LRTIs and CAP. We observed that diagnosis and a longer duration of fever (>3 days) were statistically correlated with antibiotic prescription. Diagnosing LRTI reduces antibiotic prescription, which is consistent with the British National Institute for Health and Care Excellence (NICE) guidelines stating that antibiotics should not be used routinely in bronchiolitis .In agreement with our study, there is an important double-blind, randomized, placebo-controlled trial published in 2021 which showed that antibiotics (amoxicillin) are unlikely to make a clinically important difference to the symptom burden for uncomplicated LRTI (non-pneumonic) in children—both overall and for the key clinical subgroups  where antibiotic prescribing is most common .In terms of CAP, both the USA and British guidelines state that age should be one of the key determining variables for antibiotic prescription owing to the predominance of viral etiology in children under the age of two ,17.Several studies have been conducted to identify the factors that influence antibiotic prescription in pediatric patients with respiratory infections. Among these, a study performed on febrile children referred to emergency departments across Europe reported that, similar to our findings, a longer fever duration was correlated with antibiotic prescription. In contrast to our findings, an association with antibiotic prescription was also detected for focal or diffuse abnormalities in chest X-rays, higher CRP values, and an older age .Another study on this topic evaluated a cohort of pediatric patients with LRTI who were referred to the PED and found that CRP, white blood cell count, body temperature, and pleural pain were all associated with antibiotic prescription . Other sAccording to the World Health Organization, pneumonia is diagnosed in all children 2–59 months old who have tachypnea and/or chest retractions. They should be treated at home for five days with oral amoxicillin and, in areas of low HIV prevalence and with limited resources, the duration of treatment for ‘fast breathing pneumonia’ can be decreased to three days . HoweverThe inclusion of a large number of pediatric patients and the collection of many variables and data, reporting a real-life experience regarding the characteristics of the antibiotic prescription in an Italian third-level PED, is a major strength of our study. Furthermore, identifying two determinants of antibiotic prescription such as diagnosis and duration of fever of more than 3 days can help clinicians decide whether to prescribe antibiotic therapy.The main limitation is that this is a single-center study; it would be interesting to examine the antibiotic prescription rates of various Italian hospital centers. Furthermore, patient data were obtained retrospectively and not all patients were included in the multivariate logistic regression analysis because of missing data.A further limitation of this study is that it examined a time interval for enrollment without first determining the sample size required for the investigation. Because of the disparity between LRTI and non-LRTI, the high number of patients may have inflated the results. However, we think that a real-life study also has the advantage of documenting what happens daily in our reality so that we can plan improvement strategies.In addition, we do not consider other variables investigated in the literature such as the presence of comorbidities, which has been associated with higher antibiotic prescription , the useAbout the prescription of second-line antibiotics, it is unclear how many of these agents were appropriate because we did not record the individual resistances and allergies of patients.In conclusion, our study analyzes the antibiotic prescription rate in an Italian third-level pediatric hospital, focusing on the type of molecules prescribed and the determinants of prescription. We confirmed a high prevalence of antibiotic prescription and a preference for second-line options, most likely as a result of poor adherence to guidelines, parental expectation, and difficulty discriminating between viral or bacterial LRTI. Staff training, antibiotic stewardship, periodic review of guidelines, and implementation of the use of rapid diagnostic viral tests are potential future interventions that may be introduced to lower the high rate of antibiotic prescription in our center. In the future, it will be a requirement to strengthen strategies such as training programs to boost clinical adherence to guidelines as well as to uncover more specific drivers of antibiotic prescribing. Our study adds to the fact that real-life studies frequently reveal non-adherence to guidelines, implying that stewardship programs for measures to promote clinical adherence to guidelines are required.


Textile reinforced concrete (TRC) is an innovative structure type of reinforced concrete in which the conventional steel reinforcement is replaced with fibre textile materials. The thin, cost-effective and lightweight nature enable TRC to be used to create different types of structural components for architectural and civil engineering applications. This paper presents a review of recent developments of TRC. In this review, firstly, the concept and the composition of TRC are discussed. Next, interfacial bond behaviour between fibre textile (dry and/saturated with polymer) and concrete was analysed considering the effects of polymer saturation, geometry and additives in polymer of the textile. Then, the mechanical properties (including static and dynamic properties) of TRC were reviewed. For static properties, the mechanical properties including compression, tension, flexural, shear and bond properties are discussed. For dynamic properties, the impact, seismic and cyclic properties were investigated. Furthermore, the durability of TRC under different environmental conditions, i.e., temperature/fire, humidity and wet–dry cycles, freeze–thaw, chemical and fatigue were discussed. Finally, typical engineering applications of TRC were presented. The research gaps which need to be addressed in the future for TRC research were identified as well. This review aims to present the recent advancement of TRC and inspire future research of this advanced material.  Textile reinforced concrete or TRC is defined as a material which consists of textiles, as internal reinforcement, made of long woven, knitted or even unwoven fibre rovings in at least two directions, embedded in an inorganic fine-grained binder  . A step-Fibre reinforced polymer (FRP) is a composite material composed of fibre reinforcement embedded in the polymer matrix . FRP comThe physical and mechanical properties of various fibres of FRP are given in The typical textile structures are shown in Woven fabrics are composed of two sets of yarns, warp and weft, that are formed by weaving, which is the interlacing of these sets of yarns . The yarKnitting is another form of interlacing where the thread in one set interlocks with the loops of neighbouring thread by looping . StructuThe nonwoven fabric is defined as a manufactured sheet or web structures bonded together by entangling fibres or filaments, by various mechanical, thermal and/or chemical processes . It has Three-dimensional textile has three directions in yarn architecture and/or textile architecture, regardless of whether it is made in a “one-step-process” or “multiple-step-process” ,38. In aGeerinck et al.  investigThe main advantages of using 3D textile as reinforcing material of concrete are that it offers better impact resistance than the 2D textile counterpart (because 3D textile structure has the crimpless structure compared with 2D textile structure), high formability due to their drape characteristics, high complexity shapes ,49,50. HIt needs to be clarified that textile (or only fibre) reinforced inorganic matrix composites are referred to with different names in this research, including fibre-reinforced cementitious matrix (FRCM), textile reinforced mortar (TRM) and textile reinforced concrete (TRC) . In addiFine-grained concrete with a maximum grain size (<2 mm) is mostly used for TRC. Depending on the distance between the yarns of the mesh, the maximum grain size of highly flowable consistencies concrete is 0.6 mm ,25. The Acceptance criteria, design and standard guidelines on inorganic–matrix composites have been investigated in several design guidelines including “Guide to Design and Construction of Externally Bonded Fabric-Reinforced Cementitious Matrix and Steel-Reinforced Grout Systems for Repair and Strengthening of Concrete Structures” ACI 549.4R-20) . Th. Th2+ inThe effects of textile properties, such as with/without resin, geometry and additives on the bond between textile and concrete matrix, have been investigated widely, and the bonding mechanism has also been explored. However, the research on the concrete properties, e.g., strength and aggregation, on the bond is limited, and thus is encouraged in future studies. The compressive strength of the reported compressive strength of glass textile TRC, basalt textile TRC and carbon textile TRC mainly ranges from 30 MPa to 111.46 MPa ,97,98,99f, while the specimen axial strain ε should be measured with an extensometer mounted to the central portion of the specimen [Different tensile test set-ups are proposed in the literature to analyse the tensile properties of TRC composites ,101,102.Direct tensile testing based on rectangular specimens with two displacement transducers (LVDTs) was proposed to investigate the tensile properties of TRC, the displacement rate was 1 mm/min was selected . It has −4 and 2.22 × 10−4. This similar behaviour of 3D and 2D AR-glass fibre textile TRC is expected, because the composite mechanical response is governed by matrix in the elastic stage [Tensile properties of 3D and 2D AR-glass fibre textiles reinforced cementitious matrix have been compared . The tenic stage . The conic stage . The tesic stage . The tenic stage .Research on shear strength of TRC is scarce. Indeed, the shear properties of TRC and the shear failure mechanism need to be clarified in future ,96,110. The flexural properties of TRC have been widely investigated, because most TRC elements are used for tension members (such as shells and facades), and failures were observed in bending . The fleThe flexural properties of 3D and 2D AR-glass textiles reinforced cementitious matrix are also compared. Four point bending test was performed with a span of 350 mm, and the distance between the loading pins was 100 mm. The flexural tests were performed on Instron 5885 loading machine with a rate of 2 mm/min .Bending averaged curves of the 3D and 2D AR-glass textile TRC are shown in The interfacial bonding properties between TRC and masonry substrate were analysed using a single shear test, and the most common failure mode was tensile rupture of textile . The ultThe stress transfer mechanism between the matrix and textile was investigated experimentally using direct and indirect shear tests and then described analytically with various models ,122,123.Bond properties between TRC-confined seawater sand concrete and BFRP bars under chloride corrosion environment were discussed. BFRP bars were buried in the corner of the C40 seawater sand concrete specimen  ,125). BeFew studies have been reported on the properties of TRC under impact load . This miTRC with 3D fabric was studied under impact. Three-dimensional fabrics consisted of two sets of independent two-dimensional knitted fabrics, which connected with a third set of yarns along the thickness direction . Two loaThe seismic performance of PVA textile TRC permanent formworks reinforced full-scale reinforced concrete (RC) circular columns were investigated, considering the superior tensile and ductility properties of TRC . The tesThe properties of glass textile TRC and carbon textile TRC structures under cyclic loading were investigated in the last decade ,133,134.Many experimental studies have been conducted to investigate mechanical properties of TRC. In terms of static properties, the characteristics and mechanisms of tensile and flexural properties of TRC were widely discussed, and the shear and bond properties were also extensively studied based on different kind of textile and concrete matrix. However, there is a lack of standard test method and mechanism analysis on compressive properties of TRC. In terms of dynamic performance, impact performance of TRC, the seismic performance of TRC reinforced old structures and the properties of TRC under tensile cyclic loads have been investigated. In the future, it is also necessary to pay attention to the dynamic performance of 3D textiles-TRC exposed to different loading conditions.The properties of 2D and 3D textile reinforced concrete at high temperature have not been extensively researched in the literature ,135. BasUnder the temperature of about 400 °C, the mechanical properties of 2D textile reinforced concrete decreased rapidly ,135,138.The properties of 3D textile reinforced mortar exposed to high temperature were also investigated . The thiIt has been recommended that two methods can be used to improve the fire resistance of TRC: 1) increasing the thickness of the concrete cover, (2) using carbon fibres as reinforcement since carbon fibre has high temperature tolerance up to 1500 °C. However, these two methods also increase the cost and/or self-weight  increasi. AttentiResearch on the effect of humidity on behaviour of TRC is limited ,140,141.The durability of fibre-reinforced cementitious matrix and composite-reinforced mortars subjected to wet–dry cycles were discussed with single-lap direct shear tests . The fibThe mechanical properties of glass TRC (quartzite aggregates with a maximum aggregate size of 600 μm were used for the concrete) under freeze–thaw cycles have been investigated . The speEffect of chloride freeze–thaw cycles on the bending behaviour of hybrid TRC (carbon bundles was used in the warp direction and glass bundles was used in the weft direction) was investigated . The metIt was reported that the substitution of Portland cement by the fly ash or blast furnace slag would reduce the frost resistance of TRC, because the freeze–thaw durability of concrete has a close relationship with its air void parameters , and the addition of microparticles of fly ash or blast furnace slag in the matrix can contribute to obtain the required air parameters . So, ECCWhen TRC is used in salt condition, salt ions may corrode the fibres and the concrete matrix . Convent− and SO42− would react with Ca2+ and Al3+ in the cementitious material or the hydration products of the cementitious material and generate the hydrates breaking the microstructure of the specimens, and the concrete cracked [2+ and Al3+, the durability of the specimens showed better resistance in the salt condition [The dry/wet cycle test method was mainly used to simulate chloride ion corrosion in TRC ,152. The cracked . If the ondition .To refine and enhance the service performance of TRC composites, fatigue behaviours of TRC need to be investigated. Nevertheless, the fatigue study of TRC remains a little-discussed topic . The behThe durability of TRC has also been widely studied in recent years, i.e., the tensile properties and failure modes of TRC at high temperatures have been investigated, and the concrete matrix with fire resistance deserves more attention to improve the fire resistance of TRC. The durability of TRC under the single environment or coupling action of humidity, freeze–thaw cycle, salt erosion and fatigue loads have also been preliminarily discussed. Long-term durability tests need to be carried out, because compared with the design life of the runway pavement (30 years), bridge and building (50 to 100 years), the current research results of the durability of TRC are very limited. The use of TRC can reduce the consumption of concrete by up to 85%, and the construction cost and time could be minimized due to the fact that the members can be prefabricated . The pra2 and 700 m2, respectively [2-equivalent/m2) amount was approximately 53% [Thinner TRC products were used as architectural elements, which could minimize the costs of transportation and installations. The first thin-walled ventilated facade system was built in Germany . Fydro cectively . To obtaectively . Comparetely 53% . The stately 53% , includitely 53% , the lonThe first TRC bridge was built in Germany. Glass fibre and carbon fibre textiles were used to prevent the corrosion of steel reinforcements and thus reduced the weight of the structure . In 2010TRC has been used mostly for strengthening existing steel reinforced concrete structures . In 20062 was used to strengthen the chimney [TRC also has been applied for strengthening the unreinforced masonry structures, which could be destroyed seriously under high or moderate intensity earthquakes or high wind loads . In 2008 chimney . In 2013 chimney . In 2014 chimney .TRC is also suitable for the repair of structural cracks . In ordeTRC was also chosen to confine the concrete support base of a piece of equipment in an industrial plant in the midwestern United States ,55. Beca(1)The durability and interfacial bond of FRP mesh and concrete need to be further improved. Concrete with more fly ash or blast-furnace slag could be used as the matrix of TRC to improve the corrosion resistance in salt condition and the frost resistance under the freezing and thawing cycles. Nanoparticles could be used to fill in the space of the filaments to improve the bond strength of the aging FRP mesh in the concrete.(2)Fine grain concrete is an important option to maximize the light weight advantage of TRC. Light weight concrete  could be used to reduce the weight of the TRC. Using the fly ash, which is the industrial waste, could also be benefit for the environmental protection.(3)Natural fibre textile reinforced concrete is promising to further reduce the embodied carbon of TRC for green constructions. Although the tensile strength of the natural fibre is relatively lower compared with synthetic fibres such as carbon, due to the low cost and low carbon footprint, natural fibre FRP mesh may be used to reinforce the concrete as the architectural elements or the structure elements with a requirement of lower design load.(4)Long-term test needs to be carried out for better understanding on the durability of TRC. For example, the design life of the runway pavement  is 30 ye(5)Three-dimensional textiles need to be explored to further improve the dynamic properties of TRC. Three-dimensional textiles need more research and applications in the future due to their excellent impact assistance properties. Three-dimensional textiles with various type of fabrics and matrix need to be investigated in different conditions.(6)Self-healing and self-sensing properties of TRC are important for smart infrastructure development. There are no studies related to fabric self-healing in TRC; however, ECC may be used as the matrix of TRC in harsh conditions due to its advantage of self-healing. Carbon fibre could be considered to provide the self-sensing properties in TRC due to its electrical conductivity.This paper presents a state-of-the-art review of TRC in terms of its properties and durability. The concept of TRC was discussed and typical FRP reinforcements and commonly used concrete matrices were presented. Then the bond behaviour between FRP reinforcement and concrete matrix was reviewed considering the effect of polymer saturation of the FRP reinforcement, geometry of FRP reinforcement and additives in polymer of FRP reinforcement. Afterwards, the mechanical properties of TRC were reviewed including static and dynamic properties. For static properties, the compression, tension, flexural, shear and bond properties were discussed. For dynamic properties, the impact, seismic and cyclic fatigue properties were included. Furthermore, the durability of TRC was reviewed including temperature/fire, humidity and wet–dry cycles, freeze–thaw, chemical and fatigue conditions. Finally, some engineering applications of TRC were presented. This review highlighted the desirable advantages of TRC structures which offer a solution to material saving through lightweight construction. However, there are still some research gaps that need to be addressed. The key conclusions and future outlooks are presented below:


T-θ curve and τ-γ curve of the specimen were measured in the experiment, and the failure mode of the specimen was analyzed. Subsequently, a reasonable finite element model was established using ABAQUS software, and the variation in various parameters surrounding the performance of the specimen was analyzed. Based on the experimental and finite element results, a formula for calculating the bearing capacity of the specimen was established. According to both the experimental and numerical results, the torsional bearing capacity of C-CF-CFRP-ST, defined as the torque endured by the specimen with maximum shear strain, was determined to be 15,000 με, together with its corresponding calculation formula. After the test, it was demonstrated that the main components of the concrete-filled CFRP-steel tube composite material—the steel tube and the concrete—could be used as reusable resources.In order to study the torsional performance of steel tube concrete after reinforcement with a carbon-fiber-reinforced polymer (CFRP), the mechanical properties of 18 specimens were studied from both experimental and finite element perspectives. The  Concrete-filled CFRP-steel tubes are composite materials, and its main components—a steel tube and concrete—are reusable resources. In particular, in recent years, composite structures of concrete, steel, and FRP have been research hotspots . The conLiu Y et al.  investigTherefore, an experimental and numerical study was conducted on circular CF-CFRP-ST (C-CF-CFRP-ST) specimens loaded with torsional moments. A total of 18 specimens, including 15 C-CF-CFRP-ST and 3 C-CFST specimens, were designed and tested. Numerical analysis was carried out for circular CF-CFRP-ST columns under torsion on the basis of the experimental results achieved. Then, a parametric study was conducted to explore the influence of principle factors, such as the CFPR layers, the strength of concrete and steel, and the steel ratio, on the torsional behavior of C-CF-CFRP-ST. Finally, an expression was proposed to estimate the torsional bearing capacity of C-CF-CFRP-ST based on the experimental and numerical analysis results.mt, m1, and fcu. According to the requirements of the Technical Specification for CFST (GB 50936-2014) [L of all test pieces was 360 mm, the outer diameter Ds of the steel tube was 120 mm, and the thickness ts of the steel tube was 2 mm. The other parameters of the specimens are shown in The torsional performance tests of 15 circular CFRP CFSTs and 3 circular CFSTs were studied. The main parameters included 36-2014) , the lenfy, fu, Es, vs and ε′ of steel used for specimens are shown in The specific ratio of the concrete is shown in fcu of class A, B, and C concrete for 28 d are 35.1 MPa, 46.1 MPa, and 54.9 MPa respectively, and the elastic moduli Ec are 31.5 GPa, 33 GPa, and 35.2 GPa respectively.Finally, the cube compressive strengths The carbon fiber used was woven by the Japanese company Toray. The main performance indices of carbon fiber are shown in The loading diagram of the C-CF-CFRP-ST specimen is shown in εt, εl, and ε45.The rotation angle is converted via the linear displacement generated via the tension of the displacement meter connected to the rigid rotating shaft. As shown in In the initial loading stage, the linear relationship between the displacement and torque is reached, and the torsional deformation of the specimen can hardly be observed. When the torque is continuously applied, the transverse CFRP begins to fracture, the torque decreases to a certain extent, and then the longitudinal CFRP begins to fracture. After large-area fracture of CFRP, the torque still increases slightly, and the specimens show good ductility. In the later stage of loading, the specimens are pulled and cracked. For specimens without the longitudinal CFRP or with fewer longitudinal CFRP layers than the transverse CFRP, the load does not decrease significantly when the transverse CFRP breaks. All test pieces after loading are shown in After loading, the steel tube was cut. It can be seen that there are many cracks in the concrete, and they do not penetrate the section. This shows that at the initial stage of loading, the concrete and the outer tube work together, while at the later stage of loading, the concrete and the outer tube are separated, and relative dislocation occurs between them. The damage to the concrete is shown in T-θ curve of the specimen. The curve is roughly divided into four stages: in the first elastic section, the steel tube and concrete resist torque together, and the stiffness is large; in the second elastic section (from the concrete cracking to the steel entering the elastic–plastic stage), the tensile cracking of concrete gradually exits the work, and the stiffness is lower than that in the first stage; in the third stage (steel yielding to transverse CFRP fracture), the specimen deformation increases rapidly, and the torque increases slowly; and in the fourth stage, the transverse CFRP breaks until the specimen is damaged. With the increase in torque, the longitudinal CFRP also breaks successively. The specimen after CFRP fracture is equivalent to the concrete-filled steel tubular specimen.mt is certain and mt ≤ 2 and ml ≥ 1, there is a large steep drop section in the T-θ curve of the specimens, and the corresponding angle decreases with the increase in ml. The reasons are as follows: when the transverse CFRP breaks, the longitudinal CFRP immediately peels off from the steel tube, accelerating the fracture of the transverse CFRP; the higher the number of layers of longitudinal CFRP, the easier it is to peel off, and the smaller the corresponding angular displacement during a steep drop. When ml is constant and ml ≠ 0, with the increase in mt, the steep falling section of the T-θ curve is less as well as less obvious. When the number of transverse CFRP layers is small, the effect of the longitudinal CFRP is more significant than that of the transverse CFRP. With the fracture of the transverse CFRP, the longitudinal CFRP immediately peels off, and the T-θ curve of the specimen has an obvious steep drop section. When there are many transverse CFRP layers, because the CFRP is locally fractured, the transverse CFRP at the non-fractured part still has a strong constraint on the longitudinal CFRP.For C-CF-CFRP-ST specimens, when τ-γ) curves of the circular concrete-filled CFRP-steel tube torsional specimens.Wsct is the torsional section modulus.τ-γ curve is basically consistent with that of the T-θ curve.Using Formula (2), strain can be calculated for the circular CFRP concrete-filled steel tube. It can be seen that the law of the T-ε curves of the specimens. It can be seen that εcf and εs are basically the same, which indicates that the two materials can work together. In addition, both εl and εt are positive, while ε45 is negative.T-εs curve of the partial C-CF-CFRP-ST specimens, where εsl, εst, and εs45 represent the longitudinal strain, transverse strain, and strain in the 45° direction of the steel tube, respectively, and εcfl, εcft, and εcf45 represent the longitudinal strain, transverse strain, and strain in the 45° direction of CFRP, respectively.The finite element models (FEMs), consisting of concrete, square steel tube, CFRP, and end plate, were built according to the dimensions of the tested specimens, as described in T-θ curve simulation results and the test results of the performance of the C-CF-CFRP-ST specimens. It can be seen that the simulation results are in good agreement with the experimental results.In this section, in order to more clearly verify the rationality of the finite element model, the failure mode diagrams of the experiment and finite element are compared separately. T-θ curve of the C-CF-CFRP-ST specimens. Because the concrete has micro-cracks and some concrete breaks, points 1–2 are the elastic stage of stiffness degradation. After this, the torque is mainly borne by the outer CFRP steel tube, but the inner concrete plays a good filling role, avoiding the buckling of the outer tube and ensuring that the steel tube and CFRP can fully leverage their respective strengths. At this time, the transverse CFRP and the longitudinal CFRP are not broken, the rotation angle of the specimen is about to increase sharply, and the T-θ curve is relatively flat. Torque corresponding to point 4 is defined as the torsional bearing capacity, point 5 corresponds to transverse CFRP fracture, point 6 corresponds to longitudinal CFRP fracture, and point 7 corresponds to 45° [s to 45° ,16,17.L = 360 mm, Ds = 120 mm, ts = 2.0 mm, fcu = 60 MPa , Ec = 4700 f ′c0.5 , fy = 345 MPa, ξs = 0.605, ξcf = 0.125, and η = 0.159.The following are the calculation parameters: The stress distribution of the concrete is shown in L = 360 mm, Ds = 120 mm, ts = 2.0 mm, fcu = 60 MPa, Ec = 4700 f ′c0.5(f ′c = 44.8 MPa), fy = 345 MPa, α = 0.07, ξcf = 0.125, and η = 0.159).The influence laws of the above parameters are analyzed through calculation examples (T-θ) curve of the C-CF-CFRP-ST specimens. With the improvement in the strength of the concrete and steel materials, the bearing capacity of the specimens is improved, and the influence of steel is more obvious.α, the curve shape barely changes, but the initial stiffness and bearing capacity increase significantly.A reasonable definition of torsional strength has practical significance. If the torsional strength is defined as too small, the component performance cannot be leveraged, which will lead to problems such as material waste. If the torsional strength is defined as too large, the safety reserve of the components is not enough, which may lead to engineering quality problems . The torfy = 235 MPa~460 MPa, fcu = 30 MPa~90 MPa, α = 0.05~0.2, ξs = 0.2~4, ξcf = 0~0.6, and η = 0~1. The relationship between the torsional strength τcfscy and the above parameters is regressed:fcfscy refers to the axial compressive strength of the CFRP concrete-filled steel tube.Applicable scope: the length–diameter ratio is 3, Wcfsct represents torsional section modulus.The calculation expression of the torsional bearing capacity of CFRP concrete-filled steel tubular is as follows:Tuc of torsional bearing capacity and the test result Tue. The average value of Tuc/Tue of the circular specimens is 0.916, and the mean square deviation is 0.05.In order to better introduce the conclusion section, all conclusions are classified and presented in T-θ curve of the CFRP concrete-filled steel tubule is given. The curve is characterized by the elastic stage from the beginning of loading to the cracking of concrete. At this time, the torque is borne by the outer tube and concrete, and the T-θ curve at this stage is linear. When the concrete cracks appear, the specimen enters the elastic–plastic stage. At this time, with the continuous increase in torque, the concrete cracks gradually develop, the concrete continues to withdraw from its load-bearing function, the torsional stiffness gradually decreases, and most of the torque is borne by the steel tube. When most of the concrete no longer contributes to the structural load, the specimen enters the plastic reinforcement stage. Because of the restraint effect of the outer tube, the broken concrete is still whole, and the buckling of the steel tube is restrained. The steep drop in the T-θ curve is due to the fracture of the transverse and longitudinal carbon fibers, which also shows that CFRP CFST has stronger torsional resistance than CFST alone.The typical z-axis component τyz of the shear stress of the concrete/steel tube in the middle section of the specimen is evenly distributed along the length direction of the specimen. The maximum tensile stress of the concrete in the middle section of the circular specimen increases from inside to outside along the section radius, and the maximum tensile stress is evenly distributed along the length direction of the specimen.The At the initial stage of loading, the interaction force between the steel tube and concrete is small. The interaction force between the steel tube and concrete is equal in the symmetrical position of the same section, and the interaction force between the steel tube and concrete is evenly distributed along the axis.With the development of green buildings, it is becoming more and more important to determine whether constituent materials can be used as renewable resources after the structure reaches its service life. The concrete-filled CFRP-steel tube examined in this study is made of steel and concrete, and the steel tube and concrete in its main components could be used as reusable resources. The steel tube and concrete performance after tests will also be studied in the future.Based on the results of this study, the following conclusions can be made:


Immunoglobulin G4 (IgG4) is a member of the human immunoglobulin G (IgG) subclass, a protein involved in immunity to pathogens and the body’s resistance system. IgG4-related diseases (IgG4-RD) are intractable diseases in which IgG4 levels in the blood are elevated, causing inflammation in organs such as the liver, pancreas, and salivary glands. IgG4-RD are known to be more prevalent in males than in females, but the etiology remains to be elucidated. This study was conducted to investigate the relationship between gut microbiota (GM) and serum IgG4 levels in the general population.In this study, the relationship between IgG4 levels and GM evaluated in male and female groups of the general population using causal inference. The study included 191 men and 207 women aged 40 years or older from Shika-machi, Ishikawa. GM DNA was analyzed for the 16S rRNA gene sequence using next-generation sequencing. Participants were bifurcated into high and low IgG4 groups, depending on median serum IgG4 levels.Anaerostipes, Lachnospiraceae, Megasphaera, and [Eubacterium] hallii group were associated with IgG4 levels in women, while Megasphaera, [Eubacterium] hallii group, Faecalibacterium, Ruminococcus.1, and Romboutsia were associated with IgG4 levels in men. Linear non-Gaussian acyclic model indicated three genera, Megasphaera, [Eubacterium] hallii group, and Anaerostipes, and showed a presumed causal association with IgG4 levels in women.ANCOVA, Tukey’s HSD, linear discriminant analysis effect size, least absolute shrinkage and selection operator logistic regression model, and correlation analysis revealed that This differential impact of the GM on IgG4 levels based on sex is a novel and intriguing finding. AlthougIn recent years, there has been increasing attention in medical research towards the gut microbiota (GM). It has been found that the GM plays a crucial role in maintaining human health and influencing the development of diseases . AdditioTo date, no studies have examined the causal relationship between GM and serum IgG4 levels in the general population. The GM varies widely according to sex . IgG4-RD22.1The participants were 398 residents (191 men and 207 women) aged 40 years or older, of Shika-machi, Hakui-gun, Ishikawa Prefecture, Japan, whose fecal samples were collected in 2019. The following five conditions were excluded from the analysis. 1) participants without measured serum IgG4 levels, 2) patients taking immunosuppressive drugs as described below; Methotrexate and Enbrel, 3) patients taking medications that significantly affect GM as described below; antibiotics, steroids, bowel regulators and antibacterial agents, proton pump inhibitor (PPI), 4) patients suspected cancer and IgG4-related disease, 5) individuals with missing data, 6) patients with inflammatory bowel disease (IBD).2.2Data from the Shika-machi Super Preventive Health Examination, a population survey aimed at establishing preventive methods for lifestyle-related diseases, were used. The survey was conducted between 2019. The four model districts selected from the Shika area were Horimatsu, Higashimasuho, Tsuchida, and Higashiki .2). Venous blood was collected early in the morning after a 12-hour fast. The 24-hour urinary sodium excretion was calculated based on the 24-hour urinary creatinine and sodium excretion values  was calculated by dividing the current weight (kg) by the square of the height ; Immunoglobulin G (IgG) ; Immunoglobulin E (IgE) ; 50% hemolytic unit of complement (CH50) ; Anti-CCP antibody ; antinuclear antibody (ANA) (anti-nuclear antibody (ANA) (FA) [FR], FUJIREBIO INC., Tokyo, Japan); Aniti-SS-A/Ro antibody ; rheumatoid factor (RF) levels .2.3Fecal samples were collected using previously described methods  and stor2.4For microbiome analysis, QIIME2 software was used . Demulti2.5Statistical analysis and machine learning were performed using Python (version 3.10.9)  or R, usth–75th percentile). The significance of differences in clinical information between the groups was assessed using Student’s t-test for normally distributed data and the Wilcoxson rank-sum test for non-normally distributed data.The clinical information of the participants underwent a normality assessment using the Shapiro-Wilk test. Normally distributed data are expressed as mean ± standard deviation, while non-normally distributed data are presented as median  from the “glmnet” package in R  model was built using “LiNGAM” in Python . The bac33.1Data on GM were procured from the fecal specimens of 234 study participants. The study dismissed 138 samples lacking IgG4 quantification, six individuals under immunosuppressive or gut flora-altering medications, one potential cancer case, and one suspected IgG4-RD case. None of the participants had IBD. In total, 88 patients  participated in the analysis. 3.2Anaerostipes were more prevalent in women than men  had VIF <10 in all participants. In LASSO in all participants, none of the 13 bacterial genera had statistically significant odds ratios. The classification prediction model in all participants was the area under the receiver operating characteristic curve showed 0.658, sensitivity 0.750, and specificity 0.568  had VIF <10 in male. Of the 12 bacterial genera, only Romboutsia was statistically significant with an odds ratio of 2.696   was associated with a decrease in serum IgG4 levels. In the robustness analysis of causal results, a causal direction from Megasphaera to IgG4 was detected in 82.6% of cases  and from group C to IgG4 in 78.3% of cases  in all participants. A causal direction from Megasphaera to IgG4 was detected in 81.8% of cases  and from group C to IgG4 in 59.1% of cases  in women. In contrast, no causal relationship between bacterial genus and IgG4 could be inferred in males.4Anaerostipes than men in the general population. Causal inference in women showed that Megasphaera increased IgG4 levels, while the groups including [Eubacterium] hallii group and Anaerostipes decreased IgG4 levels. In men, Megasphaera, [Eubacterium] hallii group, Faecalibacterium, Ruminococcus.1, and Romboutsia were important bacterial genera for classifying high IgG4 groups and low IgG4 groups. No bacterial genera presented a causal relationship with serum IgG4 levels in men. Serum IgG4 levels may be associated with changes in the gut bacterial genera.Women had a significantly higher proportion of Blautia and elevated succinate may be responsible for hepatitis  . IL-4, ILactobacilli and Bifidobacteria are non-spore-forming, gram-positive, lactic acid-producing bacteria. Despite some common properties, Lactobacilli and Bifidobacteria belong to two taxonomically distinct groups: the genus Lactobacillus in the phylum Firmicutes and the genus Bifidobacterium in the phylum Actinobacteria, respectively  the results revealed in the present study, in which the proportion of Anaerostipes present in a suspected causal role in reducing IgG4 was significantly higher in women, and (ii) the previously reported fact that women have a lower incidence of IgG4-RD than men. These results may lead to a new hypothesis that women are less likely to develop IgG4-RD than men due to the abundance of Anaerostipes in the gut. To elucidate the pathogenesis of IgG4-RD of unknown cause, the metabolites derived from gut bacteria that regulate serum IgG4 levels need to be investigated in detail in the future.In conclusion, The raw data of the sequencing was registered at DNA Data Bank of Japan (DDBJ) (Number DRA016467). The studies involving humans were approved by the ethics committee for Human Studies at Kanazawa University Hospital. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.AK: Conceptualization, Data curation, Project administration, Validation, Visualization, Writing – original draft, Writing – review & editing. SK: Conceptualization, Funding acquisition, Methodology, Project administration, Supervision, Writing – original draft, Writing – review & editing. KoO: Methodology, Validation, Writing – review & editing, Data curation. YM: Data curation, Investigation, Methodology, Validation, Writing – review & editing. KaO: Methodology, Writing – review & editing. RM: Data curation, Methodology, Validation, Writing – review & editing. YI: Methodology, Writing – review & editing. SH: Investigation, Writing – review & editing. IM: Investigation, Writing – review & editing. HF: Investigation, Writing – review & editing. MK: Investigation, Writing – review & editing. HT: Data curation, Writing – review & editing. AH: Investigation, Writing – review & editing. HN: Writing – review & editing, Investigation. SO: Funding acquisition, Investigation, Supervision, Writing – review & editing.


Use of Broad-spectrum antibiotics is related closely to increasing antimicrobial resistance. Reports on antibiotic prescriptions for Chinese children were rare. We described the prescribing patterns of antibiotic prescriptions for Chinese children from 2017 to 2019 based on the Anatomical Therapeutic Chemical Classification (ATC classification); the Access, Watch, and Reserve (AWaRe) classification from the World Health Organization (WHO), and the Management of Antibiotic Classification in China.A 1-day point-prevalence survey (PPSs) on antibiotics prescribing for Chinese children was conducted in hospitalized children from 17 centers in 10 Chinese provinces from 1 September 2017 to 30 November 2019.A total of 4,982 antibiotic prescriptions for Chinese children were included in the analysis. There were 76 types of antibiotic agents in total, 22 (28.9%) of which accounted for 90% of all antibiotic prescriptions. The top-three antibiotics prescribed for children were azithromycin , ceftriaxone  and latamoxef . Third-generation cephalosporins  were the most commonly prescribed antibiotic classes. On the basis of the AWaRe classification, the Watch group antibiotics accounted for 76.3% and Access group antibiotics accounted for 12.1% of all antibiotic prescriptions. On the basis of the China classification, we showed that 26.5% of antibiotic prescriptions were in the Unrestricted group, 53.6% in the Restricted group, and 14.5% in the Special group.The proportion of antibiotics included in the Watch group and the Special group was high in children in China. The AWaRe classification and China classification for antibiotic prescriptions could be used to supply detailed data for antibiotic stewardship as a simple metric. The World Health Organization launched a global action plan for antimicrobial resistance. One of the key strategies is to carry out surveys on antibiotic prescribing to optimize use of antimicrobial agents.Antimicrobial resistance has become a global threat to public health in the 21Exposure to antibiotics is a major driver of antimicrobial resistance. Rational use of antibiotics is a major tool to slow the emergence of resistant pathogens, especially multidrug-resistant organisms. Broad-spectrum antibiotics have higher resistance potential. It is particularly important to assess the relative use of broad-spectrum antibiotics for children in China.Data reports on the pattern of antibiotics prescribing for Chinese children are rare. Some sporadic studies have reported the use of antibiotic agents for a certain type of infection  but such results cannot represent the overall picture of antibiotics prescribing for Chinese children. Developing a series of strategies for optimizing antimicrobial use based on such results is difficult. A lack of practical and simple tools to assess the relative proportion of broad-spectrum antibiotics, the relevant data are limited.st WHO Expert Committee divided antibacterial agents for children into three categories: Access, Watch, and Reserve (AWaRe). These categories were modified in 2019 , whereas the antibiotics prescribed for children and neonates were significantly different . MoreoveHere, we aimed to present the general prescription patterns for antibiotics given to children. We focused on the proportion of broad-spectrum antibacterial agents for common indications in children for 3 years from 2017 to 2019 based on the Anatomical Therapeutical Chemical (ATC) Classification, the WHO AWaRe classification, and the Management of Antibiotic Classification in China.A 1-day point-prevalence survey was completed in September–November annually from 2017 to 2019. 17 participating centers from 10 provinces in China joined in for this project. Children (age range: 29 days to 18 years old) who were hospitalized in participating hospitals were included in this survey. The wards involved were as follows: internal medicine wards , pediatric surgery, and intensive care units  from 2017 to 2019. This survey collected detailed information about patients who were prescribed antibiotics, such as their ages, body weights, and the antimicrobial agents that they used (as well as their doses and routes of administration). The total number of patients in the wards in each hospital was also documented. The indications for antibiotics were as follows: pneumonia; bronchitis; viral co-infection with bacteria treatment for surgical diseases; surgical prophylaxis; medical prophylaxis; sepsis; catheter-related bloodstream infection; central nervous system (CNS) infections; skin/soft tissue infections (SSTI); urinary tract infections (UTI); joint/bone infections; cardiac infections; acute otitis media (AOM); upper respiratory tract infections (URTI); lymphadenitis; gastrointestinal (GI) tract infections; pyrexia of unknown origin (PUO); febrile neutropenia/fever; other; and unknown. The reasons for antibiotic use was selected from the structured entry diagnosis. If the reason was not in the catalog, “other” was selected. If the reason was not clear, “unknown” was selected. The indications for which antibiotic prescriptions were <10 would be merged. We examined the patterns of antimicrobial use of the pediatric units in joined hospitals. 11 of the centers were children's hospitals, three were general hospitals, and three were healthcare centers for women and children. All hospitals were tertiary and teaching hospitals. The ethics committees at Shenzhen Children's Hospital and all participating hospitals approved the procedures in this study.https://garpec-31.mobilemd.cn/login.aspx) was used to collect results. All participating centers logged into this database using a specific username and password and uploaded their data online. The data from 2017 to 2019 were merged for analysis.An internet-based Electronic Data Capture  were analyzed. Only antibacterial agents were analyzed, whereas antifungal, antiviral, antitubercular agents, and antiparasitic drugs were excluded. Children with infections were classified as having community-acquired infections (CAIs) if the onset of infection was ≤ 48 h after admission, and hospital-acquired infections (HAIs), if the onset was >48 h after admission.According to Chinese antibiotic classification, the antibacterial drugs were classified into three groups: Unrestricted, Restricted, and Special group. There was no correspondence in the lists of the three groups between the Chinese and WHO classifications. The Unrestricted group includes antibiotics like ampicillin, azithromycin for oral, and cefaclor, which are safe, affordable, and effective. The Restricted group includes antibiotics like cefoperazone/sulbactam, which have a higher potential bacterial resistance and/or a higher price. The Special use group includes antibiotics like vancomycin and meropenem, which can induce serious adverse effects and are expensive. The Special antibiotic group lists were the same in different districts and hospitals across China. The Unrestricted and Restricted antibiotic groups were slightly different in different provinces and hospitals. In this study, the lists of Unrestricted and Restricted antibiotic groups were integrated by merging the lists applied in the Tianjin Children's Hospital  and Shenzhen Children's Hospital .The antibiotic list of WHO AWaRe groups, as well as Unrestricted, Restricted, and Special groups of antibiotics in China, is shown in Antibiotics that were not on the list of the WHO ATC classification were classified into a similar group according to their pharmacological characteristics. For example, cefathiamidine was classified as a first-generation cephalosporins.Patterns of antibiotic prescription were described with a drug utilization (DU) of 90% . Antibiotic prescriptions in this multi-center point prevalence survey were classified on the basis of the ATC classification, AWaRe classification, and antibiotic classification in China.For statistical analyses, Microsoft Excel 2007  and SPSS 22.0  were used.via the intravenous route and 306 (6.1%) were administered via the oral route. The rate of antibiotic prescribing in pediatric wards in general hospitals (71.5%) was the highest, followed by in children's hospitals (68.9%) and maternal and children's hospitals (49.9%) (P < 0.05). The antibiotic prescribing rate in provincial hospitals (71.1%) was higher than in district hospitals (52.8%) (P < 0.05). The characteristics of antibiotic prescriptions in different hospitals are shown in Seventeen centers located in 10 Chinese provinces participated in this survey. Antibiotic prescribing data from 5,996 hospitalized children were collected and 4,043 (67.4%) patients were prescribed antibiotics for treatment or prophylaxis. The sum of antibiotic prescriptions was 4,982. A total of 3,154 (78.0%) children were prescribed only one antibiotic and 889 (21.98%) children received combination antibiotic therapies. There were 614  prescriptions for targeted use and 4,368  for empirical use. Of 4,982 antibiotic prescriptions, 79 (1.7%) antibiotic prescriptions were for hospital-acquired infections, 4,335 (93.4%) for community-acquired infections, and 230 (4.9%) were for an unknown cause. Meanwhile, 331 (6.6%) prescriptions were used for antibiotic prophylaxis and 4,651 (93.4%) for treatment. Among the antibiotics for hospitalized children in China, 4,676 (93.9%) were given The most three common reasons for antibiotic use in children in our survey were pneumonia , treatment for surgical diseasees , and bronchitis . The detailed distribution of indications for Chinese children is shown in Of the 4,982 antibiotic prescriptions for children, there were 76 types of antibiotic agents in total, and 22 (28.9%) antibiotic agents accounted for 90% of antibiotic prescriptions.The five most common antibiotics prescribed for children  were azithromycin , ceftriaxone , latamoxef , cefoperazone sulbactam , and meropenem  .via the intravenous route and 198 (28.9%) via the oral route.Of the 684 azithromycin prescriptions, 486 (71.1%) were given Of the 4,982 antibiotic prescriptions for children, the top five classes of antibacterial agents prescribed for children were third-generation cephalosporins , macrolides , beta lactam-beta lactamase inhibitors , carbapenems , and second-generation cephalosporins  .Of the 402 carbapenems prescriptions, meropenem was the most common, accounting for 71.6% of all carbapenems prescriptions. Of the 1,913 third generation cephalosporins prescriptions, ceftriaxone  was the most common, followed by latamoxef , cefoperazone sulbactam , ceftazidime , and ceftizoxime  .P < 0.05).According to the AWaRe classification, 76 antibiotic agents were included in our survey. There were 18 (23.7%) antibiotic agents in the Access group (accounting for 12.1% of antibiotic prescriptions), 42 (55.3%) antibiotic agents in the Watch group (accounting for 76.3% of antibiotic prescriptions), and 6 (7.9%) antibiotic agents in the Reserve group (accounting for 2.1% of antibiotic prescriptions). There were three (3.9%) antibiotic agents in the not-recommended group, accounting for 8.3% of antibiotic prescriptions. 29 (38.2%) antibiotic agents of all antibiotic types accounted for 90% of all antibiotic prescriptions. The median proportion of antibiotics in the Watch group was 74.4%  in different hospitals . The proIn the Access group, the commonly prescribed antibiotic agents were amoxicillin-clavulanic acid , metronidazole , and cefazolin . In the Watch group, the top-three antibiotics were azithromycin , ceftriaxone , and latamoxef . Detailed information on the antibiotic types in each group based on the WHO AWaRe classifications is shown in P < 0.05).Seventy-seven antibiotic agents were included in our survey from 2017 to 2019, and 34 (44.2%) antibiotic agents covered 90% of prescriptions. There were 15 (19.5%) types of antibiotic agents in the Unrestricted group (accounting for 26.5% of antibiotic prescriptions), 23 (29.9%) types of antibiotic agents in the Restricted group (accounting for 53.6% of antibiotic prescriptions), and 9 (11.7%) types of antibiotic agents in the Special group (accounting for 14.5% of antibiotic prescriptions). The median proportion of antibiotics in the Restricted group and Special group was 56.7%  and 11.9% , respectively, in different hospitals . The pron = 1,319), the commonly prescribed antibiotic agents were ceftriaxone , erythromycin , and azithromycin . In the Restricted group, the top-three antibiotics were azithromycin , latamoxef  and cefoperazone-sulbactam . In the Special group, the top-three antibiotics were meropenem , vancomycin  and imipenem-cilastatin .In the Unrestricted group  were for acute pneumonia in Chinese children. Pneumonia was the most common indication for antibiotics in Chinese children. A total of 2,632 antibiotic prescriptions were for 2,142 children suffering from pneumonia. A total of 434 (16.5%) antibiotic prescriptions in 326 (15.2%) children were a targeted application and 2,198 (83.5%) antibiotic prescriptions in 1,816 (84.8%) children were based on empirical use. The five most frequently prescribed antibiotic agents were azithromycin , ceftriaxone , latamoxef , amoxicillin-clavulanic acid , and erythromycin . The top-five antibiotic classes prescribed for children were third-generation cephalosporins , macrolides , beta lactam-beta lactamase inhibitors , carbapenems  and second-generation cephalosporins .Of the 2,632 antibiotic prescriptions for pneumonia in Chinese children, 13 antibiotic agents included in the Access group accounted for 10.6%, whereas 35 antibiotic agents in the Watch group accounted for 78.4% of all antibiotic prescriptions. In the Watch group, azithromycin  was the most commonly prescribed antibiotic, followed by ceftriaxone , and latamoxef .Of the 2,632 antibiotic prescriptions for pneumonia, 14 antibiotic agents included in the Unrestricted group accounted for 26.9%, whereas 20 antibiotic agents included in the Restricted group accounted for 58.9%. The Special group antibiotics (which were restricted and authorized only by consultants) accounted for 11.8%.In December 2,011, the National Health Commission of the People's Republic of China initiated a special campaign to restrict the use of antibiotics. The antibiotic utilization rate and antibiotic use density for children and adults showed an apparent decline in some hospitals , 5.Escherichia coli to ceftriaxone and meropenem was 52.3–56.9% and 2.4–4.3% isolated in Chinese children from 2017 to 2019. The resistance of Klebsiella pneumoniae to ceftriaxone and meropenem has been documented in 56.1–60.9% and 19.8-23.6% of isolated Chinese children from 2017 to 2019  in China, but this is not required in other countries . The incA1555G. Compared to European children (0.19%), the carrier rate of A1555G in Chinese newborns (0.12%) was lower . Aminoglycosides were one of the most commonly prescribed antibiotic classes in countries such as India (10.4%) and Australia 14%) , 14. Vir% , 14. Vas lower , 17. AccE.coli. and K. pneumoniae to ceftriaxone was >50%  of all antibiotic prescriptions. The proportion of third-generation cephalosporins prescribed to children in China in our survey is higher than that in Australia (10.20%), Ghana 18.5%), and Italy (26.3%) , Haemophilus influenza (21.1%), and Staphylococcus aureus (11.9%), and the proportions of penicillin-resistant and penicillin-intermediate to Streptococcus pneumoniae which was the most common bacteria for pneumonia in children were 15.9% and 1.2% , were rarely used in North America or Europe, possibly because of a higher incidence of side effects, such as bleeding . Ampicillin-sulbactam was the most frequently prescribed antibiotic for children with pneumonia in Japan . Accordi%. Ampicibleeding . The antMycoplasma pneumonia and a positive penicillin skin test. Azithromycin has been misused because of misinterpretation of test results for Mycoplasma pneumoniae. Many physicians incorrectly take the positivity of IgG or IgM to Mycoplasma pneumoniae as the only indication for prescribing macrolides. We showed that >70% of azithromycin prescriptions were for intravenous use. Intravenous azithromycin is off-label and can cause adverse cardiovascular effects in children , North America (3.2%), the Eastern Mediterranean (3.4%), Europe (3.4%), and South-East Asia (1.9%) . Macrolichildren . The appEnterobacterales increased from 3.0% in 2005 to 10.2% in 2017  was the most commonly prescribed antibiotic, followed by vancomycin (2.8%). The proportion of prescriptions for meropenem and vancomycin of all prescriptions was higher than that for meropenem (4.5%) and vancomycin (2.0%) in India, which has a high prevalence of antimicrobial resistance  in children, data from the worldwide antibiotic resistance and prescribing in European children (ARPEC) , while 9In this study, 76 antibiotic types were prescribed in different hospitals. It seems probable that too many types of antibiotics were prescribed for Chinese children. Of course, not all of the types were used in a single hospital, but our survey showed that antibiotics prescribed in different regions and hospitals varied greatly. A national essential medicine list of antibiotics for children should be formulated and extended to all hospitals. In addition, 30 antibiotics belonging to the unclassified group accounted for 5.46% of total antibiotic prescriptions according to China's classification. This meant many kinds of antibiotics were not in the classified groups and accounted for a small percentage. Some antibiotic agents are not classified into groups, because they are not commonly used for children like aminoglycosides and quinolones in China. This was not beneficial for antibiotic stewardship. In fact, all antibiotics should be classified into groups for encouraging optimal use and decreasing the unnecessary kinds of antibiotics prescribed by standardized training for doctors.The WHO AWaRe classification system ranks antibiotics to enable the pattern of antibiotic prescribing to be seen clearly and to facilitate the creation of an antimicrobial strategy. However, carbapenems and glycopeptides  are put in the Watch group together with third-generation cephalosporins and macrolides. Making the difference clear based on the AWaRe classification is difficult. China's antibiotics management system classifies this antibiotic group separately as special use grade. A combination of the two classification systems could display the distribution of broad-spectrum antimicrobial agents readily, and help to formulate targeted management strategies.This study had several strengths. First, we focused on the distribution of antibacterial agents for Chinese children hospitalized in tertiary hospitals. This design reduced the bias of surveillance of data from different-level hospitals and different populations. Second, a standardized and structured point-prevalence survey was applied to collect data from 17 hospitals located in 10 provinces in China. This approach contributed to the reliability of data, a large dataset, and the representativeness of antibiotic prescriptions for children in China. Third, this is the first study to describe the prescription pattern of different types of antibiotic agents for children by combining the ATC classification, WHO AWaRe, and the Management of Antibiotic Classification in China.The present study had several limitations. First, a lack of microbiology data, antimicrobial susceptibility results, and detailed patient characteristics hampered determination of the appropriateness of antibiotic use. Second, this was a cross-sectional survey, so data on the duration of antibiotic therapy and switching patterns were not collected. Third, the participating hospitals contributed the data voluntarily, and the eligibility of such data might not have been uploaded on the server. Fourth, the majority of hospitals joined in this survey located in northern, eastern, and southern China while only two hospitals were from western China. Thus, the results might not be representative of all of China. This study did not include all inpatient wards like hematology and oncology wards. In the next surveys, more details on antibiotic prescribing such as duration of treatment, pathogens, and underlying diseases will be collected and more hospitals, especially those located in western China and rural districts, will be added to the monitoring network to increase the representativeness.We provided baseline data on antibiotic prescriptions in the real world. Targeted antimicrobial stewardship can be formulated using our data. The aims of the strategies are to reduce the use of broad-spectrum antibiotic agents and increase the use of narrow-spectrum antibiotics to avoid further exacerbations of antimicrobial resistance. At national and regional levels, physicians, pharmacologists, microbiologists and policymakers, and others should collaborate to improve the quality of antibiotic prescribing for Chinese children.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by the Ethics Committees at Shenzhen Children's Hospital (201801504). Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin.YY, JZ, WZ, YZ, and JD were responsible for the study concept and design. YY organized all hospitals to collect data. JZ, XM, LT, DT, LL, YL, GL, LS, WZ, JQ, GL, WL, QC, and LW collected the data of antibiotic prescriptions and edited the manuscript. JZ and KW contributed to the data management and analyses. JZ contributed to the interpretation of data and writing of the manuscript. YY, YZ, and JD revised the manuscript. All authors reviewed and agreed the final manuscript.This research was funded by Project of the Expert Committee on Clinical Application and Drug Resistance Evaluation of Antimicrobial Drugs of the National Health Commission (No. KJYWZWH-OT-02-2021-01), Shenzhen Healthcare Research Project (No. SZLY2018016), and Shenzhen Fund for Guangdong Provincial High level Clinical Key Specialties (No. SZGSP012). The sponsors had no any role in the study design, data collection, data analysis, data interpretation, writing of report, or decision to submit the article for publication.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.