Antibiotic prescribing is common worldwide. There are several original studies about antibiotic prescribing in the healthcare setting of Iran reporting different levels of prescribing. The aim of this systematic review and meta-analysis was to determine the prevalence of antibiotic prescribing in both inpatient and outpatient settings in Iran, an example of a developing country.To identify published studies on antibiotic prescribing, databases such as ISI, Scopus, PubMed, Google Scholar, and Electronic Persian were searched in Iran till January 2020. Eligible studies were those analyzing original data on the prescription and use of antibiotics in outpatient or inpatient settings in Iran. Moreover, all studies that used an intervention to improve antibiotic prescribing were included. The quality of the included studies was assessed using self-administered quality assessment criteria. The meta-analysis of prevalence of antibiotic prescribing was conducted based on the meta-analysis of observational studies in epidemiology guidelines. To calculate pooled rates, the random-effects model was used.p < .05).A total of 54 studies (39 outpatients and 15 inpatients) were included in this study. The median of antibiotic prescribing in the outpatient and inpatient settings accounted for 45.25% and 68.2% of patients, respectively. The results of meta-analysis also showed that the antibiotic prescribing accounted for 45% of prescriptions in outpatient settings and 39.5%, 66%, and 75.3% of patients in all wards, pediatrics wards, and ICU wards of inpatient settings, respectively. The most commonly prescribed antibiotic classes in outpatient settings were penicillins, cephalosporins, and macrolides, while in inpatient settings, these were cephalosporins, penicillins, and carbapenems. There were seven studies using interventions to improve antibiotic prescribing pattern. It should be mentioned that intervention in a study had a statistically significant effect on improving antibiotic prescribing (Prevalence of antibiotic prescribing in Iran is high. Our findings highlight the need for urgent action to improve prescription practices. It seems that developing a national plan to improve antibiotic prescribing is necessary. Prescribing and use of antibiotics have spread worldwide. These medications are among the most frequently used and expensive drugs for patients as well as health care organizations . AlthougMonitoring the patterns and rates of antibiotic prescribing are among the recommended strategies to prevent their overuse . In addiMany studies estimated the rate of antibiotic prescribing in inpatient and outpatient settings in different countries and reported different estimates –25. HoweA comprehensive search strategy was developed using terms and MeSH terms related to antibiotic , prescribing , and Iran .Electronic databases  were searched using customized search strategies on Jan 2020. Persian electronic databases, including MagIran and SID (Scientific Information Database), were searched using Persian terms which are similar to the above-mentioned ones. Google Scholar was also searched using Persian search terms, to avoid missing relevant papers. Finally, the list of references in all retrieved papers was reviewed to identify extra relevant studies.The original studies included were those investigating antibiotic prescribing rate in patients’ prescriptions or hospital patients’ records, those using an intervention to improve antibiotic prescribing pattern and the ones conducted in either inpatient or outpatient settings in Iran and published in Persian or English. Due to the necessity of prescribing antibiotics in surgery, dentistry, and burn patients, the studies on these populations were not included. In addition, conference papers, letters, opinions, and dissertations were also excluded.One of the reviewers searched the databases (R.A). Screening the title and abstract of potentially relevant papers were carried out by two independent reviewers . Any potential conflict about the inclusion of papers was discussed by them and after reaching a consensus, they made an appropriate decision. Subsequently, the full text of the included papers was retrieved to fulfil the aims of this review, and if not available, the full-texts were requested from the authors via email.After reviewing the full-text for each included paper, the following information was extracted: authors, year of study, region, setting, sample size, unit of analysis, percentage of antibiotic prescribing , the number of antibiotics in each prescription , and antibiotic classes and names. In the case of interventional studies, in addition to the above mentioned information, the type of study, the type of intervention used, and its effects were also extracted. Since patients’ age and gender, type of disease, type of insurance, and type of cost payment have not been investigated in most of the included studies, we could not consider this type of data in our analysis.The methodological quality of the included studies was evaluated by a self-administered checklist based on related studies , 37 and Total quality scores ranged from 0 to 10 . Two independent reviewers scored the quality of each study according to the mentioned criteria and the third reviewer resolved potential discrepancies.The median and interquartile range (IQR) of antibiotic prescribing rates were calculated. Subgroup analyses were conducted based on the healthcare setting type (inpatient and outpatient). To standardize the meta-analysis methodology, the rates of antibiotic prescribing were obtained. Data were analyzed using Comprehensive Meta-Analysis (CMA) software (Version 2.0). The meta-analysis was conducted based on the meta-analysis of observational studies in epidemiology guidelines . InterveFigure The included studies were conducted from 1995 to 2016. In total, 39 (72%) studies were conducted in outpatient settings and 15 (28%) in inpatient settings. Out of 39 studies in outpatient settings, 7 (18%) studies evaluated the effects of interventions on antibiotic prescription –51.The quality assessment of the included studies showed that none of them fulfilled all the quality criteria. Twelve (22%) studies were of high quality, 35 (65%) were of moderate quality, and 7 (13%) were of poor quality. Only 18 studies (33%) listing their limitations.p < 0.05) [All of the interventional studies were conducted in outpatient settings during 1995–2012. Since there was difference in the percentage of antibiotic prescribing in before and after of interventions, the results of interventional studies were reported separately from other outpatient studies (Table  < 0.05) .Table 2GAmong the reviewed studies, 15 (28%) ones were done in inpatient settings during 1997–2014. In two studies 13%) , 53, the% , 53, tAmong the reviewed studies, 32 (59%) ones were conducted in outpatient settings during 1995–2019. In these studies, the unit of analysis was either prescriptions or patients, and the minimum and maximum sample sizes were 441 and 200,000,000, respectively. Most of the studies (75%) did not report the most commonly prescribed antibiotic classes. Penicillin, cephalosporin, macrolides, as well as aminoglycosides were the most commonly prescribed antibiotic classes. Amoxicillin, penicillin, co-amoxiclav, and cefixime were the most frequently prescribed antibiotics . The results of a global study showed that antibiotic consumption increased by 65% in 76 countries from 2000 to 2015 (from 21.1 to 34.8 billion DDDs) . The expThe results of this study showed that nearly half of the outpatients received antibiotics in Iran . The results of a study by Yin et al.  showed tThe most common antibiotic classes prescribed in inpatient settings were cephalosporins, penicillins, and carbapenems, while in outpatient settings, they were penicillins, cephalosporins, and macrolides. Furthermore, the most frequently prescribed antibiotics were ceftriaxone and cefazolin in inpatient settings and amoxicillin, penicillin, co-amoxiclav, and cefixime in outpatient settings. Antibiotics classes such as penicillins, cephalosporins, quinolones, and macrolides were the most common antibiotic classes consumed in 76 countries during 2000–2015 . AlthougOur results may help increase the awareness and knowledge about the antimicrobials use and identifying areas of overuse in this country. Moreover, Iranian health policymakers could develop a national plan to improve the clinical application of antibiotics and consider use of recommended IT-based interventions.This study is the first to describe the prevalence of antibiotic prescriptions in Iran. It also provides an overview of interventions taken to improve antibiotic prescriptions in this country. However, the Persian search engine is limited but we conducted several search strategies such as searching Google Scholar, hand-searching, and searching reference lists of the included studies. We did exclude different kind of studies: studies describing antibiotic prescribing in surgery, dentistry, and burn patients (because of the necessity of antibiotics); studies that reported antibiotic prescription without the frequencies that we sought ; and studies that assessed only special classes of antibiotics such as vancomycin, imipenem, aminoglycosides, meropenem, ciprofloxacin (because they do not provide a comprehensive picture of antibiotic prescribing).This study showed that antibiotic prescribing rate in both inpatient and outpatient settings in Iran surpasses the WHO recommendations and exceeds that in many other countries. Moreover, this study revealed that traditional educational interventions showed no significant effect on reducing antibiotic prescribing rate. In order to decrease antibiotic prescribing by physicians, IT-based interventions such as electronic feedback on physicians’ performance, electronic prescribing, and clinical decision support systems may hold promise.Additional file 1: Attachment 1. Percentage of antibiotic prescribing in all wards of hospitals in Iran. Attachment 2. Percentage of antibiotic prescribing in pediatrics wards of hospitals in Iran. Attachment 3. Percentage of antibiotic prescribing in ICU wards of hospitals in Iran.


Antimicrobial resistance (AMR) is one of the most urgent global health threats with low-resource countries being disproportionately affected. Targeted interventions require insight in antibiotic prescription practices. A point prevalence survey (PPS) is a well-known tool to get insight in antibiotic dispensing practices in hospitals and identify areas for improvement. Here, we describe the results of a PPS performed in a tertiary, regional and district hospital in Kilimanjaro region in Tanzania.A PPS was performed in the Kilimanjaro Christian Medical Centre , Mawenzi  and St. Joseph (district) hospital in November and December 2016. Antibiotic use in all patients admitted more than 24 h and those undergoing surgery was recorded. All clinical wards were included except the pediatrics. Data from a single ward were collected on the same day.n = 94, 29.8%), metronidazole  and other antibiotics belonging to the penicillin class  were most commonly prescribed. Antibiotics prescribed for surgical prophylaxis were continued for more than 3 days in 57% of cases.A total of 399 patients were included in the PPS: 232 patients from KCMC, 94 from Mawenzi hospital and 73 patients from St. Joseph hospital. Overall prevalence of antibiotic use was 44.0%: 38% in KCMC, 59% in Mawenzi and 63% in St. Joseph. Ceftriaxone (Our study shows a rate of broad-spectrum antibiotic use in Tanzanian hospitals and prolonged surgical antibiotic prophylaxis being a common practice. PPS is an important tool to improve future antibiotic use in Tanzania hospitals. Antimicrobial resistance (AMR) is a serious threat to global health and human development . Low-andPoint prevalence surveys (PPS) are a well-established tool to measure the prevalence of antibiotic use in hospitals. Results can be used to identify targets for antimicrobial stewardship teams and improve local antimicrobial prescription practices . DiffereThis study was conducted in three hospitals located in Moshi Municipality in Kilimanjaro region in North-eastern Tanzania: the Kilimanjaro Christian Medical Centre (KCMC), Mawenzi Regional Hospital and St. Joseph Council Designated Hospital. KCMC has a 640-bed capacity and is the second largest consultant referral hospital in the country, serving patients from northern and central regions of Tanzania. KCMC comprises a Medical University College, which offers undergraduate and post-graduate training. It has a well-equipped clinical laboratory for patient care with a back-up advanced biotechnology laboratory. Most patients are referrals from regional or district hospitals. Mawenzi is a government-owned hospital with a 300-bed capacity and serves mainly the community of Kilimanjaro Region. In this hospital the patients are referrals from district hospitals or health centers. St. Joseph Hospital is a Catholic Church owned and Council Designated Hospital (CDH) for Moshi Municipal Council with a 100-bed capacity. The majority of patients are attended as the first point of care.https://www.ecdc.europa.eu/en/publications-data/point-prevalence-survey-healthcare-associated-infections-and-antimicrobial-use-3) standard protocol form for conducting a PPS [The survey took place on different days in November and December 2016. Data from inpatients admitted to the clinical wards, with the exception of the pediatric wards, were collected. Data of all patients on a single ward were collected on the same day. For all patients on a ward, it was recorded whether they used at least one systemic antibiotic at 8 a.m. on the day of the survey. In that case, additional data regarding the antibiotic use were entered. Data about antibiotic use was also recorded for patients who had undergone surgery and were administered antibiotics for surgical prophylaxis in the previous 24 h. Data were collected on a written form based on the European Centres for Disease Control and Prevention (ECDC) . Descriptive statistics were used to summarize findings. Analyses were done using STATA statistical software version 15 .Data from a total of 399 patients were registered from which 232, 94 and 73 patients were from the KCMC, Mawenzi hospital and St. Joseph hospital, respectively. At the day of PPS, a total number of 176 patients (44%) were using antibiotics and 19 patients (4.8%) suffered from an active hospital acquired infection , metronidazole  and penicillins  were the most commonly prescribed. Ceftriaxone was commonly prescribed in KCMC and St. Joseph, whereas penicillins  were more commonly prescribed in the Mawenzi regional hospital. Meropenem was used in two patients in KCMC as treatment for a skin and soft tissue infection. , an acute hospital acquired infection , surgical prophylaxis  or medical prophylaxis  and unknown reason . The site of infections in community acquired infection were mostly skin and soft tissue infection , lower respiratory tract , genitourinary infection , gastroenteritis/diarrhoea  and sepsis . Surgical prophylaxis was the indication for antibiotic prescription in respectively, 35, 24 and 30% in the KCMC, Mawenzi and St. Joseph. Antibiotics prescribed for surgical prophylaxis were ceftriaxone , penicillins , occasionally in combination with gentamicin  and metronidazole . Surgical prophylaxis is preferably limited to a single dose immediately before initiation of surgery [The indications for antibiotics were treatment of a community acquired infection  of the treatment was targeted, i.e. based on the result of a bacterial culture.Additional assessments were done in KCMC: in 37 (42%) patient files, the precise reason for starting antibiotics was unclear. An antibiotic treatment plan, containing details on proposed duration of antibiotic therapy, was included in only 2% of files. Regarding additional examinations, measurement of biomarkers of inflammation (erythrocyte sedimentation rate or C-reactive protein), relevant radiology or a microbiology test were done in respectively 13 (15%), 21 (24%) and 12 (14%) of the patients. In 47% of the patients, no additional investigation had taken place. During the start of the antimicrobial treatment, only 3%  as well as surveys from individual sub-Saharan African countries such as Botswana 70.6%  and KenyThe prevalence of antibiotic use in the tertiary hospital (KCMC) was lower than in the regional and district hospital. This might be explained by more conservative antibiotic prescription practices in a teaching hospital, but also because of a lower prevalence of patients with infectious diseases.Enterobacteriaceae, and complicate empirical treatment of severe bacterial infections. In view of the high prevalence of colonization and infections with ESBL positive Enterobacteriaceae in Tanzanian hospitals [The third-generation cephalosporin ceftriaxone and metronidazole were the most commonly prescribed antibiotics. Ceftriaxone was prescribed for both community and hospital-acquired infections, as well as for surgical prophylaxis. The frequent use of this broad-spectrum antibiotic in KCMC and hospitals across sub-Saharan Africa was reported earlier , 19. Injospitals –23, incrospitals . At the Antibiotics for treatment of infections were frequently prescribed empirically without results of microbiologic or other examinations to guide treatment. With the increasing burden of AMR across hospitals in Tanzania, expansion of diagnostic facilities to guide antibiotic therapy in hospital inpatients is urgently needed.Next to extensive prescription of broad-spectrum antibiotics, another identified key area for improvement was prolonged surgical prophylaxis. International guidelines recommend against prolonged surgical antibiotic prophylaxis . ProlongFinally, documentation of an antibiotic plan was only available in the case notes of two patients. Efforts on documentation of an antibiotic plan are useful in promoting i.v. to oral orders, de-escalation strategies and avoidance of duplicate therapies , 29.Our study has different limitations. First, at the time of the PPS, there was a low bed – occupancy probably because of being end of the year, giving an impression of a third of patients having been studied. Second, the PPS could not be on a single day for the entire hospital, but was performed on a single day per ward.In conclusion, the results of the PPS show a high rate of broad-spectrum antibiotic use in Tanzanian hospitals. In addition, surgical antibiotic prophylaxis prolongation is common practice. PPS can be an important aid in improvement strategies of future antibiotic use in Tanzanian hospitals.Additional file 1. Data collection tool: A modified European Centers for Disease Control and Prevention (ECDC) data collection tool for antimicrobial use.


Here, we investigated the long-term effects of RTX in nine refractory MuSK-MG patients with a follow-up ranging from 17 months to 13 years. In patients’ sera, we titrated MuSK-specific IgG (MuSK-IgG) and MuSK-IgG4, along with total IgG and IgG4 levels. Optimal response to RTX was defined as the achievement and maintenance of the status of minimal manifestations (MM)-or-better together with a ≥ 50% steroid reduction, withdrawal of immunosuppressants, and no need for plasma-exchange or intravenous immunoglobulin. After a course of RTX, eight patients improved, with optimal response in six, while only one patient did not respond. At baseline, MuSK-IgG and MuSK-IgG4 serum titers were positive in all patients, ranging from 2.15 to 49.5 nmol/L and from 0.33 to 46.2 nmol/L, respectively. MuSK Abs mostly consisted of IgG4 (range 63.80–98.86%). RTX administration was followed by a marked reduction of MuSK Abs at 2–7 months and at 12–30 months (p < 0.02 for MuSK-IgG and p < 0.01 for MuSK-IgG4). In patients with a longer follow-up, MuSK Ab titers remained suppressed, paralleling clinical response. In the patient who achieved long-term complete remission, MuSK-IgG4 was no longer detectable within 2 years, while MuSK-IgG remained positive at very low titers up to 10 years after RTX. In the patient who did not respond, MuSK-IgG and MuSK-IgG4 remained unchanged. In this patient series, total IgG and IgG4 transiently decreased (p < 0.05) at 2–7 months after RTX. The different trends of reduction between MuSK-IgG4 and total IgG4 after RTX support the view that short-lived Ab-secreting cells are the main producers of MuSK Abs. The ratio between short-lived Ab-secreting cells and long-lived plasma cells may influence the response to RTX, and B-cell severe depletion may reduce self-maintaining autoimmune reactivity.The use of rituximab (RTX), an anti-CD20 monoclonal antibody (Ab), in refractory myasthenia gravis (MG) is associated with a better response in patients with Abs to the muscle-specific tyrosine kinase (MuSK) than in other MG subgroups. Anti-MuSK Abs are mostly IgG4 with proven pathogenicity and positive correlation with clinical severity. The rapid and sustained response to RTX may be related to MuSK Ab production by short-lived Ab-secreting cells derived from specific CD20 Rituximab (RTX) is a chimeric mouse/human monoclonal antibody (Ab) directed against the B-lymphocyte membrane protein CD20. RTX acts through complement-mediated cytotoxicity, Ab-dependent cell-mediated cytotoxicity, and induction of apoptosis, leading to a profound depletion of circulating naïve and memory B cells . Since pIgG4 develops after prolonged antigen exposure and constitutes the least represented IgG subclass. IgG4 Abs may exert a protective role in allergy and are generally considered non-pathogenic, owing to their inability to activate complement and to cross-link identical antigens after Fab-arm exchange . More reMyasthenia gravis (MG) is a rare disease of the neuromuscular junction caused by Abs against postsynaptic membrane proteins, such as the acetylcholine receptor (AChR), the muscle-specific tyrosine kinase (MuSK), or the low-density receptor-related protein 4 (LRP4). MG with Abs to MuSK (MuSK-MG) was one of the first diseases in which IgG4 pathogenicity was demonstrated  and currin vitro  classification ; two pat2 once a week for four consecutive weeks, plus a single dose of 375 mg/m2 after 3 months. Infusion was preceded by intravenous methylprednisolone and oral antihistamine medication to minimize acute reactions.RTX was administered according to the non-Hodgkin lymphoma regimen adopted in our institution. A RTX course consisted of an infusion of 375 mg/mBefore treatment, patients were screened for active infections including viral hepatitis (B and C) and tuberculosis  and for We classified response to RTX considering changes in both clinical status and treatment. Optimal response was defined by the achievement and maintenance of the status of minimal manifestations (MM) or better , togetheClinical changes were assessed as post-intervention status (PIS) .Fifty-two serum samples from the nine patients included in the study (four to seven samples per patient) were collected before and after RTX treatment. Samples were stored at −20°C until the analysis was performed.125I-labeled MuSK , according to the manufacturer’s instruction, with minor modifications. In brief, 50 μl of a 10X serum dilution (in assay buffer) was incubated overnightwith 50 μlof 125I-MuSK. The antigen/Ab complexes were precipitated by the addition of 50 μl of goat anti-human IgG and separated by centrifugation. Serum samples with saturating titers were further analyzed at different dilutions with normal human serum  (MuSK-IgG titration was performed using human recombinant 125I-MuSK solution [from the aforementioned radioimmunoassay (RIA)] was incubated with 0.2 μl of patients’ serum for 8–12 h at 4°C . Serum samples were previously diluted with NHS to maintain the antigen/Ab binding in the linear zone of the slope. After adding5 μl of sheep anti-human IgG4 , samples were incubated overnight at 4°C. Then, 15 μl of anti-sheep IgG anti-serum  was added for 4 h at room temperature to precipitate MuSK-IgG4Abs complexed to 125I-MuSK. After final washes, the radioactivity was measured in a gammacounter. Results were expressed as 125I-MuSK nanomoles per liter. All samples from the same patient were titrated in the same batch to limit inter-assay variability.MuSK-IgG4 Abs were determined as described by Tsiamalos and coworkers with minor modifications . BrieflyTotal IgG and IgG4 serum levels were measured by turbidimetry  on the Optilite instrument according to the manufacturer’s recommendations. Normal range is 8–18 g/L for total IgG and 0.04–0.86 g/L for the IgG4 subclass. Serological analysis was performed blind of clinical data.+ cell normal values ranged from 100 to 400 cells/mm3 (7–16% of lymphocyte count).B lymphocytes in peripheral blood were evaluated as routine assessment in patients treated with RTX, by standard flowcytometry in our institution’s central laboratories. CD19vs 2–7 months vs 12–30 months); Student’st test was performed between two groups. A p-value < 0.05 was considered significant  with refractory MuSK-MG, treated with RTX between July 2006 and October 2018. The patients’ demographics, baseline and post-treatment clinical data, and follow-up duration are shown in Age at infusion ranged 38–73 years (mean 50.4 ± 12.8). The interval between disease onset and RTX administration varied between 3 and 21 years (mean 11 ± 6.04). At the time of treatment, MG severity ranged from IIb to IIIb according tothe MGFA classification , and allOptimal response to RTX was recorded in six of nine patients (66.6%). Prednisone was tapered off in two patients (#2 and #7) and was reduced by 75% to 87.5% of the pretreatment dosage  in the others. After a single course of RTX, patient #7 achieved electromyography (EMG)-confirmed complete stable remission (CSR), persisting at the last follow-up, 13 years after RTX administration and 5 years from immunosuppression withdrawal. In the other patients, optimal response to RTX (PIS ranging from CSR to MM) lasted 28–42 months in patients #2 and #3, and is still ongoing 20 to 71 months after RTX, in patients #1, #6, and #8 see . A seconTwo patients showed a partial response since they did not achieve MM status, although prednisone and immunosuppressive therapy were reduced by 50%. In patient #9 who had developed a myopathic face, weakness of facial muscles remained unchanged, while dysarthria and neck weakness markedly improved. Patient #4, suffering from tongue wasting and severe bulbar weakness, did not improve after a first cycle of RTX, while he responded to a second course with improvement of dysarthria and partial reversal of tongue atrophy. RTX was well tolerated with no infusion reactions or long-term side effects.The results of serological assays, together with PIS and changes in B-cell count, are reported in MuSK-IgG and MuSK-IgG4 titers did not change after a course of RTX in the only patient (#4) who did not respond , while, p < 0.02 for MuSK-IgG and p < 0.01 for MuSK-IgG4, by ANOVA), while the MuSK-IgG4/MuSK-IgG ratio was reduced significantly only at 2–7 months after RTX .For statistical analysis, we compared MuSK-IgG and MuSK-IgG4 baseline levels with those at 2–7 months and at 12–30 months after RTX in eight patients (samples from patient #5 were not available). We found a significant reduction at both time points . Patient #7 had a higher IgG4/IgG ratio (7.3%) that persisted (after a temporary decrease in the first 2 years after RTX) in the long-term follow-up, when MuSK-IgG4 was no longer detectable.p = 0.15 for total IgG; p = 0.17 for IgG4, by ANOVA). However, we found a significant reduction when comparing baseline levels with those at 2–7 months ; afterward, total IgG and IgG4 returned to pretreatment levels. The total IgG4/IgG ratio was unchanged at both time points.Total IgG and IgG4 did not significantly change at 2–7 and 12–30 months after RTX when compared to the baseline levels . In patient #2, an increase in serum MuSK Abs, and above all, in MuSK-IgG4 heralded clinical deterioration. Conversely, in patient #7, who achieved long-standing CSR, MuSK-IgG4 was no longer detectable several years before MuSK-IgG negativization. Overall, these data agree with the view that MuSK-IgG4 is pathogenic and is mostly produced by short-lived Ab-secreting cells.2/week for 4 weeks plus an infusion monthly for the next 2 months, which is similar to that adopted in our study, was associated with the lowest relapse rate in MuSK-MG  can herald a clinical relapse, changes in Ab titers may be used to monitor clinical response.There is no established protocol for RTX administration in MG, although the non-Hodgkin lymphoma regimen has been the most common induction treatment . Recentl MuSK-MG . RTX cyc MuSK-MG , 16, 29  MuSK-MG , 28, 42, MuSK-MG . ConsideIt is well known that RTX is highly effective in IgG4-associated diseases and can deplete short-lived Ab-secreting cells without affecting long-lived plasma cells . The efOverall, our data show that the therapeutic effects of RTX can persist for several years after treatment, suggesting that, by depleting autoreactive B-cell clones, RTX may significantly disrupt the immunopathogenic circuit responsible for disease maintenance. It is well known that B-cell activity depends on T–B lymphocyte cross talk and cooperation. Future studies should investigate how RTX affects such an interaction, particularly regarding specific T- and B-cell repertoires.The datasets generated for this study are available on request to the corresponding author.The studies involving human participants were reviewed and approved by Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario “A. Gemelli” – I.R.C.C.S. The patients/participants provided their written informed consent to participate in this study. Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article.MM, EB, and AE wrote the manuscript. MM, UB, and EB designed the experiments. GS, RI, and AE collected the serum samples and clinical data. UB, CN, FG, LT, and CP performed the experiments. EB and AE analyzed the data.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.


Common mental disorders are frequent psychiatric comorbid conditions among people with HIV/AIDS. The presence of such psychiatric disorders negatively affects the treatment adherence, viral load suppression, quality of life, treatment outcomes and functionality of people with HIV/AIDS. However, available studies in Ethiopia have a great variation and inconsistency of reported results have been observed regarding the magnitude and associated factors of common mental disorder. Thus, conducting a systematic review and meta-analysis of existing literatures can have a paramount importance to show its summarized figure.2 test was used to assess the heterogeneity of primary articles. The result of the test showed that there was heterogeneity between primary studies. This leads us to execute a random effect meta-analysis to estimate the pooled prevalence of common mental disorder with corresponding 95% confidence interval.Literatures search was performed using databases  among people with HIV/AIDS in Ethiopia. The highest prevalence of common mental disorder (35.20%) was observed among studies in which Kessler-10 was used as a screening tool. Single marital status , HIV/AIDS-related stigma  and current job unavailability  had statistically significant association with common mental disorder.The result of this review showed that nearly one among three individuals with HIV/AIDS is suffering from common mental disorder in Ethiopia. This calls a need to integrate the mental health and psycho-social support into the HIV/AIDS care.CRD42019132402. Registered on 05/08/2019.PROSPERO-  Common mental disorder (CMD), sometimes called mental distress or psychological distress is a gross name given to describe a range of psychological disturbances explained by the presentation of depressive, anxiety, and/or somatic symptoms , 2. SuchNowadays, CMD becomes a common public health problem both in developing and developed populations , 6, 7. ICMD becomes more common among people with chronic medical conditions, particularly HIV/AIDS , 11. ForThe presence of comorbid CMD can have negative and complicated impacts on the treatment outcome and quality of life of individuals. For instance, CMD diminishes the treatment adherence , viral lAlthough there are some studies reporting the prevalence and predictors of CMD among people with HIV/AIDS in Ethiopia, a great variation and inconsistency of reported results have been observed , 23. TheThe first objective of this review was to measure the pooled prevalence of common mental disorder among people attending anti-retroviral therapy (ART) clinics of Ethiopia. This can help for policymakers and clinical practitioners to integrate the mental health and psycho-social support service as an added treatment modality to the HIV/AIDS care. The second objective was to compare the pooled prevalence of common mental disorder among studies based on the screening tools of CMD. Finally, this systematic review and meta-analysis identified predictors of common mental disorder among people with HIV/AIDS. This can be helpful for the prevention, early identification and interventions of common mental disorder among people with HIV/AIDS by preventing and/or minimizing its risk factors.Systematic search of both published and unpublished primary articles were conducted using different databases . Grey literatures were identified from Google and Google scholar. We also performed literatures search using direct web sites of local (Ethiopian) journals. Articles related to the prevalence and/or associated factors of common mental disorder among people living with HIV/AIDS were retrieved. Key terms used to retrieve primary articles were  OR Psychological distress) OR Mental distress) AND HIV/AIDS) OR Anti-Retroviral Therapy) OR Highly Active Anti-Retroviral Therapy) AND Ethiopian).th, 2019 were considered for this systematic review and meta-analysis. This systematic review and meta-analysis was carried out in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guideline [All relevant articles available online until May 15uideline   with original data reporting the prevalence of common mental disorder and/or its associated factors were considered.Literatures written in English language were included.Studies conducted among adults  attending ART clinics in Ethiopia were included.th, 2019 were included.Both published and unpublished articles available online until May 15In the full-text evaluation of articles, we considered study settings, target populations, age of respondents, study design, paper quality and outcomes of interest. Primary studies conducted among minors (age less than 18 years old), papers of non-Ethiopian population or non-HIV/AIDS patients, non-observational studies, papers with low quality score and studies that did not have reports of magnitude, and/or associated factors of CMD were excluded.Three authors , independently extracted all necessary data using a data extraction format prepared in Microsoft Excel. For the first objective, the data extraction format had sections of name of first author, publication year, region of the country where studies are conducted, screening tools of CMD, sample size, response rate, and prevalence of common mental disorder. Each section stands with a single column and rows were filled with data from each primary study. For the second objective , a data extraction format prepared in a two by two table form was used  for analysis. The standard error of prevalence was calculated using the binomial distribution formula for each original article. The heterogeneity of primary studies was checked using χ I2 test . In thisnel plot , 28. TheIn the first step of our literature search, a total of 325 articles were retrieved using databases . Additional six articles were also searched from Google and Google scholar. First, all searched articles were imported to End-note, and duplications were removed. After the removal of duplications, there were 185 articles considered eligibility for title and abstract evaluation. Accordingly, 141 articles were excluded and remaining 44 articles were considered for further full-text evaluation. After the full-text reading, 31 articles were further excluded due to differences in the study population, study design and outcome of interests. Finally, thirteen papers were found as eligible to be included in this systematic review and meta-analysis . However, a highly variable and inconsistent results of CMD ranging from 7.80 to 75% was reported. Regarding assessment tools of CMD, seven studies used the Kessler 10- item questionnaire, two used the Hospital Anxiety and Depression Scale (HADS) and other four used the Self-Reported Questionnaire (SRQ-20)   , 30–35, From a total of thirteen studies included in this systematic review, only four papers , 37, 39 Accordingly, single individuals were 1.83 times more likely to have common mental disorder as compared to individuals who were married and living together  Fig. .Fig. 4FAIDS-related stigma increases the odds of common mental disorder by 2.21 times among people with HIV/AIDS as compared to individuals without AIDS related stigma   Fig. .Fig. 6FLiteratures revealed that the prevalence of common mental disorder among people with HIV/AIDS is higher than the general population . The preThis systematic review showed that the pooled prevalence of common mental disorder among people with HIV/AIDS in Ethiopia was 28.83% with corresponding 95% CI of . The magnitude of common mental disorder in this systematic review and meta-analysis is higher than the reports of global prevalence (17.6%) and WHO estimation in African regions (8%) .We also performed a subgroup analysis based on screening tools that primary studies used to screen CMD among PWHA. Accordingly, the result of the sub group analysis showed that there was significant difference on the report of CMD with respect to differences in screening tools of papers. The highest prevalence (35.20%) of CMD was observed among primary articles in which K-10 was used to screen CMD and the lowest prevalence (17.76%) was reported from studies that used HADS. The possible explanation for this variation might be due to the extra ability of the K-10 (unlike HADS and SRQ) to assess somatic like symptoms in addition to depressive and anxiety symptoms , 41. ThiIn this systematic review, predictors of common mental disorder were also identified among people with HIV/AIDS using meta-analysis. The meta-analysis result showed that single marital status, HIV/AIDS-related stigma and unavailability of job had statistically significant association with CMD of people with HIV/AIDS infection.Accordingly, single individuals were 1.83 times more likely to have common mental disorder as compared to individuals who were married and living together. The possible reason for this significant association can be explained by the fact that people often feel comfortable while they have somebody close to them  to share their psychosocial distress . MoreoveThe odds of common mental disorder among people with HIV/AIDS-related stigma were increased by 2.21 times as compared to their counterparts. This might be explained by the fact that people with perceived HIV/AIDS-related stigma are more likely to have lower self-image, feeling of inferiority, guilt felling, worthlessness and social isolation which are hallmark symptoms of CMD . In addiFinally, the meta-analysis result showed that the odds of having common mental disorder among people who had no job were 1.38 times higher than those who were working at their job. This might be explained by the fact that people who engage at work can have a better source of income that improves their quality of life, and enable them to develop self-reliance (independency) . MoreoveThis review showed that the pooled prevalence of common mental disorder among people with HIV/AIDS was higher than the figure reported for the general population. The highest prevalence of common mental disorder was observed among studies used Kessler-10 to screen common mental disorder. Single marital status, HIV/AIDS-related stigma and current job unavailability were identified as factors significantly associated with common mental disorder. This demonstrates a need to integrate mental health and psycho-social support services into the HIV/AIDS care. Prevention of HIV/AIDS-related stigma and accessing job opportunities for people with HIV/AIDS are also highly recommended.Additional file 1. PRISMA-P  2015 checklist: recommended items to address in a systematic review protocol*.Additional file 2. Sample data extraction format.


Days of therapy in children < 24 months with otitis increased from 8.0 to 10.0 in Center A, while in older children decreased in Center A  and Center B . Clinical pathways combined with educational lectures is a feasible and sustainable program in reducing broad-spectrum antibiotic prescribing with stable rates over time.Antibiotic stewardship programs proved to be effective in improving prescribing appropriateness. This multicenter quasi-experimental study, aimed to assesses the stewardship impact on antibiotics prescribing in different semesters from 2014 to 2019 in three pediatric emergency departments  in Italy. All consecutive patients diagnosed with acute otitis media or pharyngitis were evaluated for inclusion. Two different stewardship were adopted: for Center A and B, clinical pathways were implemented and disseminated, and yearly lectures were held, for Center C, only pathways were implemented. Broad-spectrum prescription rates decreased significantly by 80% for pharyngitis and 29.5 to 55.2% for otitis after the implementation. In Center C, rates gradually increased from the year after the implementation. Amoxicillin dosage adjusted to pharyngitis recommendations in Center C (53.7 vs. 51.6 mg/kg/die;  Antibiotics remain the most commonly prescribed drugs in the pediatric population , with phHaemophilus influenzae, and Moraxella catarrhalis [Both conditions have a viral and a bacterial etiology: AOM is mostly caused by Streptococcus pneumoniae, non-typeable arrhalis , while aarrhalis .Although most of the pathogens remain sensible to first line amoxicillin, co-amoxiclav and III-gen cephalosporins are, respectively, prescribed in around 30% and 15% of AOM primary care cases, and in more than 24% and 15% of Group A streptococcus pharyngitis cases [To decrease or reverse this trend, various antibiotic stewardship programs (ASPs) have been implemented worldwide, focusing on different approaches .Clinical pathways have proven to be a feasible and efficient first step in improving prescribing appropriateness, especially in settings where funding is limited ,8,9,10. In October 2015, an ASP based on clinical pathways was implemented in the pediatric emergency department of Padova University Hospital. Preliminary results reported an increase in “wait-and-see” approach rate for AOM (21.7% vs. 33.1%) and an increase in narrow-spectrum antibiotics treatments for both AOM (32.0% vs. 51.6%) and pharyngitis (53.6% vs. 93.4%), with no variation in treatment failures .While there is not yet a consensus on the most effective ASP—especially in terms of settings and costs—we aimed to evaluate the efficacy and sustainability over time of ASPs based on clinical pathways with and without yearly educational lectures in three pediatric emergency departments.During the study, 4534 pharyngitis episodes were evaluated, accounting for around 3% of total pediatric emergency department visits. In total, 3249 episodes were included; the demographic characteristics of children included were similar with respect to sex, with a higher prevalence among older children in both Center B and C .p < 0.001, Center B: from 69.7% to 96.0%, p < 0.001) with a consequent decrease in broad-spectrum-antibiotic prescription rates (broad-spectrum antibiotic prescriptions)  .p = 0.002) for Center A and by 88.6% (RR 0.114 (95% CI: 0.016–0.816); p = 0.0471) for Center B, as illustrated in The interrupted time series model strongly suggest a broad-spectrum antibiotic prescriptions reduction following the introduction of the clinical pathways by 81.6% (relative risk (RR) 0.184 (95% CI: 0.072–0.471); p < 0.001) in broad-spectrum antibiotic prescriptions rates after the intervention with rates increasing monthly by 3.5% (RR 1.035 (95% CI: 1.025–1.045); p < 0.001) in the post periods in Center C.The interrupted time series model shows a 77% reduction (RR 0.230 (95% CI: 0.167–0.316); p < 0.001) after clinical pathways implementation in Center A (Amoxicillin dosage adjusted from 53.7 (IQR:7.0) to 51.6 mg/kg/die (IQR:3.8) in Center B  and the Center A .Overall, 3980 AOM visits were assessed, and 3039 met the inclusion criteria. In Center A and C, a significant difference was reported in age class in the various periods .p = 0.006) and amoxicillin prescriptions rates increased in Center A and B, with a concomitant decrease in broad-spectrum antibiotic prescriptions rates , especially cephalosporins prescriptions , even if rates did not remain stable, but decreased by 3.6% monthly (RR 0.036 (95% CI: 0.964–0.955); p < 0.001).In Center C, the highest “wait-and-see” approach rate (32.7%) and the lowest broad-spectrum antibiotic prescriptions rate (68.3%) were reported in the semester following the ASP. Initially, the intervention doubled the “wait-and-see” approach rates (RR 2.510 (95% CI: 1.832–3.349); p = 0.011) in Center A and by 55.2% (RR 0.448 (95% CI: 0.235–0.856); p = 0.015) in Center B after the clinical pathways implementation. In Center C, the intervention reduced broad-spectrum antibiotic prescriptions by 41.1% (RR 0.589 (95% CI: 0.470–0.737); p < 0.001), but in the following semesters, the broad-spectrum antibiotic prescriptions rates increased by 1.5% monthly (RR 1.015 (95% CI 1.009–1.022); p < 0.001). The interrupted time series are shown in The broad-spectrum antibiotic prescriptions rates decreased by 29.5% (RR 0.705 (95% CI: 0.538–0.923); p < 0.001), similarly to Center B (from 56.7 (IQR:14.3) to 75.0 (IQR:7.1) mg/kg/die). Co-amoxiclav dosage increase was also significant for both centers (Amoxicillin dosage increased from 50.0 (IQR:0.0) to 75.0 (IQR:5.0) mg/kg/die in Center A ( centers .DOT in children <24 months varied significantly from 8.0 (IQR:2.0) to 10.0 (IQR:0.0) just in Center A .p < 0.001) and in Center B (from 10.0 (IQR:2.0) to 8.0 (IQR:5.0) DOT; p < 0.001), while in Center C the median DOT remained 7.0 for the all periods in both age class.In older children, a variation was noted in Center A (from 8.0 (IQR:1.0) to 7.0 (IQR:2.0) DOT; In 58.0% (2310/3980) of the AOM diagnoses, there was no sign of otorrhea reported.p < 0.001, Center B: from 33.3% to 19.7%; p = 0.035), whereas a pattern similar to total AOM prescription was noted for Center C , while in Center C, the intervention was significant in increasing the “wait-and-see” approach rates immediately after the intervention (RR: 2.363 (95% CI: 1.774–3.148); p < 0.001); then, rates decreased monthly by 3.3% (RR: 0.967 (95% CI: 0.959–0.976); p < 0.001)).The “wait-and-see” approach rates increased by 68.8% after the intervention and stabilized in Center A (RR 1.688 (95% CI: 1.116–2.552); p = 0.068).The interrupted time series analysis  confirmeAmoxicillin and co-amoxiclav dosages did not differ from total AOM findings , whereasIn this multicentric study, clinical pathways combined with educational lectures proved to be a feasible ASP in decreasing and maintaining broad-spectrum antibiotic prescriptions rates over time for both AOM and pharyngitis (Center A and B). On the other hand, clinical pathways alone failed to maintain the low broad-spectrum prescription rates achieved after the intervention (Center C).The ASPs reduced co-amoxiclav and cephalosporins prescription rates for pharyngitis by around 80% in all centers. In Center C, the reduction was not maintained after the first semester, possibly due to prescribers’ fear of coinfection in Group A Streptococcus carriers . DOT cha“Wait-and-see” approach rates increased significantly in non-complicated AOM with stable rates after the ASPs implementation. The “wait-and-see” approach was introduced in the early 2000s and was included in most guidelines for the treatment of AOM ,15 with In non-complicated AOM, five median DOT for older children was achieved in Center A’s final semester, reflecting prescribers’ initial discomfort with short-course treatment. Overall median DOT might not be the most suitable indicator in assessing ASP efficacy on treatment duration when higher rates of second-line therapy  are observed, such as in Center C. A possible solution is calculating the median DOT stratified by different drugs.Our study has several caveats: first, its retrospective nature and difficulties in assessing the reasons why broad-spectrum antibiotics were prescribed. However, the same study nature allowed us to exclude the Hawthorne effect that sometimes could be argued to play a major role in the ASP success. Second, no control groups were selected; hence, we cannot conclude with a high degree of certainty that the variation in broad-spectrum antibiotic prescriptions rates is caused by the ASP implementation without considering other possible explanations. On the other hand, no policy restricting antibiotic prescriptions was implemented in the different centers during the study period, nor were there any shortages in Group A Streptococcus-rapid tests. Third, patient follow-up was beyond the aim of the study and was, therefore, not performed. Although it is possible that patients receiving broad-spectrum antibiotic prescriptions had better clinical outcomes, preliminary results reported that there was no difference in treatment failure rate nor in adverse event rate in the first and second semesters . Fourth,Despite clinical pathways proving to be a feasible ASP tool with rapid implementation and reduced applicability cost, this study revealed that without combining it with continuous education, it might have no lasting effect. In fact, the Infectious Disease Society of America recommends two core strategies to be implemented together, even if most pediatric ASPs consist of just one intervention. According to a recent systematic review, most of the studies do not report a long follow up, and few report negative results, though publication bias might contribute to this .A study trial where an ASP based on continuous clinician-specific education combined with audit and feedback was implemented in the USA outpatients setting found that following the removal of the audit and feedback, the initial reduction in broad-spectrum antibiotic prescriptions to children with acute respiratory tract infection was lost . The autClinicians and researchers interested in implementing an ASP should carefully consider their options in order to avoid inefficiency. A possible improvement in the ASPs proposed lay on the analysis timing. Data were manually collected in condition-specific data collection forms, requiring ad hoc specialists to perform data entry. One solution could be conducting random day-point prevalence surveys every couple of weeks or months in setting with rapid patients turn-over, thus limiting the time dedicated to the collection and providing more rapid estimates on prescribing behaviors ,23,24. SThis multicenter quasi-experimental study assesses the ASPs impact on antibiotics prescribing in the pediatric emergency department of three different hospitals: two tertiary-level university hospitals  and one secondary-level hospital . Each institution was randomly named with a capital letter  to keep them intentionally anonymous.The different periods considered were: one semester before and three semesters after implementation for Center A and C  and one semester before and two semesters after implementation for Center B . The study flowchart is shown in During the study period, in the pediatric emergency departments of the three hospitals, there were physicians that worked on a daily basis, specialist consultants that worked depending on the requests and residents that worked on a daily basis but changed every couple of months.Two different ASPs were adopted: for Center A and B, the intervention consisted of clinical pathway implementation and dissemination as laminated pocket-cards with yearly educational lectures for residents and pediatricians, and for Center C, the intervention consisted only of the implementation of clinical pathways with the possibility of consulting in the hospital intranet.A multidisciplinary group of experts from each center, in collaboration with the Division of Pediatric Infectious Diseases of the Children’s Hospital of Philadelphia, developed the clinical pathways for pharyngitis and AOM that were adapted to the centers’ standard of care with no changes in the algorithm .The educational lectures addressed to residents, structured physicians and specialists and held by the center ASP team, consisted of two hours of training on the diagnosis and treatments of AOM and pharyngitis with a focus on the rational for antibiotic prescribing.All consecutive patients aged two months to 14 years with an International Classification of Diseases, 9th Revision, Clinical Modification code, or descriptive diagnosis of AOM or pharyngitis admitted to the pediatric emergency department in one of the three centers were included.General exclusion criteria were immunodeficiency or immunosuppressive therapy, concomitant bacterial infections or systemic bacterial infection, craniofacial abnormalities, chronic diseases , and ongoing antibiotic therapy at admission. Pharyngitis exclusion criteria were previous tonsillectomy, periodic fever, aphthous stomatitis, pharyngitis and adenitis syndrome, and admission to the pediatric emergency department for feeding difficulties. AOM exclusion criteria were tympanostomy tubes at the time of diagnosis, chronic otitis media, and AOM complicated by mastoiditis.Pediatric emergency department visits occurring for the same patient greater than 30 days apart were analyzed as separate events.All AOM episodes with otorrhea were considered as complicated AOM; the remaining episodes were considered as non-complicated.Broad-spectrum antibiotics were defined as β-lactam and β-lactamase inhibitor combinations, second- and third-generation cephalosporins, fluoroquinolones, and macrolides. Topic antibiotics  were not considered.“Wait-and-see” approach rates (AOM only);Broad-spectrum antibiotic prescriptions rates;Rates by active agent;Amoxicillin and co-amoxiclav dosage, expressed in mg/kg/day (Center A and Center B only);Duration of therapy expressed in DOT.The following aspects of antibiotic prescriptions for pharyngitis and AOM were assessed:The “wait-and-see” approach was defined as AOM episodes with no antibiotic prescription.All clinical, demographic, diagnostic, and prescription data were manually collected from electronic medical records, using a password protected REDCap 10.0.1-© 2020 (Vanderbilt University) data collection form and stored on a secured server at the University of Padova. Privacy was guaranteed by assigning each patient a unique study-specific number and not collecting personally identifying data.Assuming that before ASP implementation, (i) in 10% of AOM episodes a “wait-and-see” approach would be chosen and in 45% of pharyngitis episodes no antibiotic would be prescribed, (ii) the broad-spectrum antibiotic prescriptions rates would be 50%, (iii) broad-spectrum antibiotic prescriptions would decrease by 25%, (iv) 15% of the episodes did not fulfill the inclusion criteria, (v) a two-tailed Type I error of 0.05 is used, and (vi) the study is required to have at least a power of 70%, we estimated a minimum sample size of 330 pharyngitis and 260 AOM episodes per period per center to detect a significant decrease in broad-spectrum antibiotic prescriptions. The power for estimating the difference between independent proportions was calculated using G Power 3.1.9.4-© 1992–2019  [https://www.wma.net/what-we-do/medical-ethics/declaration-of-helsinki/), revised in 2013. This study was approved by the Ethical Committees of all Centers (3737/AO/16). Due to the nature of the study , no informed consent was required from the patients.The investigations were carried out following the rules of the Declaration of Helsinki of 1975 .Single center results in the different periods were summarized as numbers and percentages  and as median and interquartile range (continuous variables). Categorical variables were compared with χ2 or Fisher’s 2-tailed exact test in a contingency table An interrupted time series analysis supposing an abrupt step change in monthly significative outcomes (1 and 2) using quasi-Poisson regression models was used to determine the effect of the intervention. “Wait-andOutcome data were sometimes missing 0–20%, . If varip values were two-sided.A sensitivity analysis was conducted for non-complicated AOM episodes. Data were analyzed using R statistical software  for Windows . The mulTo the best of our knowledge, this is the first attempt to study the efficacy and sustainability of ASPs over time based on clinical pathways in pediatric emergency departments. Our findings suggest that clinical pathways paired with continuous education can be effective in reducing broad-spectrum antibiotic prescription and in reaching target treatment duration. Researchers should push for efficient assessment and publication of intervention sustainability in order to help other clinicians in choosing the most suitable ASP for their setting.


Green concrete (GC) was developed for realizing sustainable development, recycling waste materials, and reducing environmental pollution. For the practical use of GC, various harmful materials must blocked from entering its cracks and pores; and its strength and durability must be improved. The use of an inorganic coating material (ICM) for GC effectively prevents the intrusion of harmful materials and repairs the concrete. ICMs can reduce the permeability and increase the durability of concrete. This study investigated GC, construction waste, and ICMs and used recycled sand and gravel as well as construction waste as substitutes for cement. The results indicate that the coarse aggregate substitution, water-binder ratio, and recycled fine aggregate substitution must be controlled suitably in GC. Furthermore, the coating layer, fine aggregate substitution, and aging of the ICM mut be controlled suitably. GC with an ICM showed poorer performance than conventional concrete, mainly because of the high porosity. Nonetheless, the ICM somewhate reduces the porosity and resists the penetration of chloride ions, thereby promoting concrete quality. Reinforced concrete is the main material used in construction projects ,2. CemenAfter the waste concrete was broken, sieved, and processed, the recycled aggregate, can be divided into recycled coarse aggregates and recycled fine aggregates. The influence of recycled coarse-grained materials on the properties of concrete was reported by previous studies ,18,19,20The aim of the present study is to achieve the sustainable use of various waste materials and reduce environmental pollution caused by waste materials ,28,29,30Although various coating materials are available, most are harmful to the environment or the human body . FurtherThere are many types of concrete surface treatments from different angles or requirements , includiSpecifically, waste is used to replace a part of the cement, and concrete filling materials are replaced with recycled coarse and fine aggregates. Then, the protective effect of an ICM on the GC surface is discussed.2 (76%), Na2O (9%), and CaO (6%) by X-ray diffraction (XRD) spectral analysis provided by panalytical x’pert Pro MPD in Malvern Panalytical Ltd. . The compressive strengths of a mortar prepared with a 20% solar photovoltaic glass powder substitution for cement on a mass basis are compared to those of a control mortar according to ASTM C311 [Solar photovoltaic glass powder provided by Zunhong Environmental Protection Co., Ltd.  is made by self-breaking and grinding by ball mill. STM C311 . The resSTM C311 . In thisInorganic coating material (ICM) came from XYPEX Chemical Corporation . The fine-grained material is used for river sand from Lanyang River. The basic physical properties and gradation distribution of the fine-grained material are shown in This study uses the coarse-grained materials produced in Lanyang River. The physical properties including specific gravity, water absorption, and maximum particle size are shown in 2 because the sand and gravel plant can only deal with the natural river bed soil and stone and cannot use construction waste for processing. After curing for 56 days, it was disintegrated to make recycled pellets. The basic properties of the granular materials, including specific gravity, water absorption, maximum diameter, and fineness modulus, are shown in The recycled fine aggregate used in this research institute is provided by Zunhong Environmental Protection Co., Ltd.  and produced by the equipment of the Jilong sand and stone plant . The design strength of the self-made concrete block in the sand and gravel plant is 280 kgf/cmThe recycled coarse aggregate used in this study is provided by Rongmin Engineering Co., Ltd.  and produced by the equipment of the Luodong sand and gravel plant . Due to the current regulations of the sand and gravel plant, only natural river bed soil and stone can be processed and construction waste can not be used for processing. This study made concrete blocks in the sand and gravel plant, and made recycled aggregate after 56 days of curing, including specific gravity, water absorption, and maximum diameter, as shown in This study explored the performance of the ICM on a GC substrate. The ACI-211 mix design method was adopted for designing the concrete base material mix, as shown in The important factors in the selection of the GC and ICM include the replacing cement, replacing coarse-grained material, replacing fine-grained material, coating type, coating material proportion, coating layer number, and coating material age. A water:cement ratio of 0.6 was used to test the physical properties, permeability, and microstructure of the concrete substrate. The effectiveness of GC coated with an ICM was discussed, and comparisons with a control group were performed. Tests were conducted according to ASTM C39M-12 . The uniThe compressive strength development curves of OPC and GC at 7, 14, 28, and 56 days show that the strength of GC was 2–8 MPa lower than that of OPC at each age. The compressive strength of recycled coarse and fine particles and photoelectric glass powder may be lower because of incomplete hydration that results from replacing general aggregates or cement. However, the compressive strength of GC at 56 days was only 6% lower than that of OPC. The hydration of GC tends to become more complete with age. The compressive strengths of OPCC and GCC are higher than those of OPC and GC, respectively, at 28 and 56 days. It is speculated that the ICM blocks the pores owing to a chemical reaction with the concrete substrate, resulting in a slight increase in compressive strength. The compressive strength of GCC at 56 days was slightly higher than that of GC, indicating that the ICM has a certain protective effect. In a base material with large pores, it is suitable to plug these pores to improve the concrete quality.An absorption test was performed according to ASTM C642-13 . FurtherThe results show that the absorption rate of all groups decreased with time. The hydration reaction in the sample tended to become more complete with time, making the pores more compact . The absWhen external water enters the specimen, it must penetrate the surface and internal capillary pores. When the pores are small or have poor connectivity, the absorption rate of the sample decrease with age. The experimental results showed that the absorption rate of each group decreased with age. In this experiment, GC had a high absorption rate owing to the high porosity of the recycled coarse and fine particles. However, GCC had a lower absorption rate, indicating that the ICM could adequately block the interior of the substrate. Because the ICM was easy to penetrate into the pores, resulting in obvious blocking effect, effectively reducing the water absorption ,32,57,58In this study, the concrete quadrupole resistance meter manufactured by Swiss proceq company was used to test. The resistance of the equipment is 10 mΩ, the rated current is 180 µA, the frequency is 72 Hz, the measurement range is 0~99 KΩ cm, and the accuracy is ± 1 Ω cm. The appearance of the instrument is shown in When the resistivity value becomes high, it can be inferred that the concrete substrate is relatively dense and the conductive path is blocked. Then, the permeability of the base material is evaluated. The results show that GC has lower resistivity than OPC at all ages. However, GCC shows increased resistivity. OPC and OPCC had the same trend. ICM can prevent the resistance from penetrating through the pores of the substrate, it caused that the OPCC and GCC specimens were shown increased resistivity.An accelerated chloride migration test was conducted according to ASTM C1202-12 . The tesThe test results show that OPC has lower chloride ion penetration than GC at 28 and 56 days. When recycled coarse and fine particles and photoelectric glass powder are used to replace general aggregates or cement, incomplete hydration causes low compactness of the substrate, resulting in high chloride ion penetration . HoweverA mercury intrusion porosimetry (MIP) test was conducted according to ASTM D4404-10 . The merIn this study, an MIP was performed at 28 days to investigate the effects of GC and ICM on the pore structure of the substrate. The scanning electron microscope s-4800 made by Hitachi company of Japan  was used to observe the microstructure. The maximum magnification of the instrument can reach 10,0000 times. The principle of the instrument is to use the electron gun to emit high-energy electron light to impact the specimen, then use the bias signal collector to detect the excited signal, and transmit it to the cathode mapping tube through the signal amplifier. As shown in The X-ray diffraction analyzer used in this study is panalytical x’pert Pro MPD. The principle of X-ray diffraction analysis is to irradiate the sample with monochromatic X-ray, and the diffracted X-ray will radiate along the conical surface at an angle of 2θ with the incident angle. By recording the diffraction intensity at different angles, the 2θ intensity diagram can be drawn. The appearance of the instrument is shown in 3S, and C2S. It can be inferred that the ICM does not penetrate 20 mm below the coating layer to cause a reaction. It is speculated that if the coating material does not penetrate the sealing layer to a depth of 5 mm, crystallization occurs under the sealing layer owing to the different chemical compositions. It can be inferred that ICMs can react to form crystals by penetrating the concrete, thereby improving the protective efficiency of the substrate.Compared with The physical properties of GC coated with an ICM show that when recycled coarse and fine particles and photoelectric glass powder are used to replace ordinary particles or cement, the porosity may become higher owing to incomplete hydration, resulting in lower compressive strength and a higher absorption value. However, when the ICM is coated on the base material, the performance of the base material improves slightly. It is speculated that the ICM reduces the porosity of the base material to improve the quality of concrete.Permeability tests show that GC had lower permeability than OPC at 28 and 56 days, indicating that the low compactness of the GC substrate resulted in high chloride penetration. However, an ICM can block chloride ion penetration and block the pores of the substrate.SEM revealed that the microstructure of GCC had needle-like structures 5 mm below the substrate surface but not 20 mm below the substrate surface. It is speculated that the ICMs are permeable and produced a chemical composition with the substrate, resulting in the obvious presence of needle-like structures 5 mm below the coating layer.


Mycobacterium tuberculosis. We explore this relationship when the fitness of the resistant strain is varied relative to that of the sensitive strain to investigate the likely long-term multi-strain dynamics of the AIDS-mediated increased emergence of drug resistance.Despite the risk of emerging drug resistance that occurs with the frequent use of antimicrobial agents, targeted and prophylactic antibiotics have been considered crucial to opportunistic infection management among the HIV/AIDS-immunocompromised. As we recently demonstrated, the disrupted selective pressures that occur in AIDS-prevalent host populations increase the probability of novel emergence. This effect is concerning, given that bacterial strains unresponsive to first-line antibiotics can be particularly dangerous to hosts whose immune response is insufficient to fight infection in the absence of antibiotic support. While greater host susceptibility within a highly immunocompromised population may offer a fitness advantage to drug-resistant bacterial strains, this advantage could be mitigated by increased morbidity and mortality among the AIDS-immunocompromised. Using a Susceptible-Exposed-Infectious-Recovered (SEIR) epidemiological model parameterized to reflect conditions in an AIDS-prevalent host population, we examine the evolutionary relationship between drug-sensitive and -resistant strains of  Among HIV/AIDS immunocompromised patients, the frequent use of antibiotics is essential in the prevention and/or treatment of many opportunistic bacterial pathogens . Yet, itWe recently demonstrated that the disrupted selective pressures associated with an AIDS-prevalent host pool can drastically increase the probability of the emergence of antibiotic resistance . EmerginMycobacterium tuberculosis as a model pathogen, we now examine the impact of the emergence and maintenance of resistance via bacterial strain circulation and the potential for strain replacement.In our previous works ,10, we mWe have chosen to focus on the developing world because, within resource-limited settings, poor sanitation and infection management enhances the burden of infectious disease, and economic constraints can hinder access to effective antibiotics . MoreoveTo explore the evolutionary and epidemiological effects of the emergence and subsequent circulation of antibiotic-resistant pathogens within a highly immunocompromised host population, we present an SEIR model , and parWhen we analyzed the evolutionary behavior of the resistant (q) strain over a one-year period, we observed an immediate and rapid increase emergence, such that, by day 365, more than 90% of infections could be expected to be attributable to q-strain emergence . This reAs would be expected, due to both curative antibiotics and a decline in available hosts , we observed a decline in total infection prevalence over the 365-day duration of the model . NeverthEven under the condition when the q-strain experiences the greatest fitness penalty (cf = 0.5), examining total TB prevalence, without analyzing the percentage of drug-resistant vs. drug-sensitive strains, would critically fail to capture overall risk: bacterial strains unresponsive to antibiotics have the potential to be particularly harmful to highly HIV/AIDS-immunocompromised populations. As further evidence of the health risk that arises due to the interplay between HIV/AIDS and emerging resistance, we found that, as HIV/AIDS prevalence increases, there is a corresponding increase in the proportion of q-strain infections, and this occurs irrespective of the relative fitness of the resistant strain .Finally, Both the emergence of antibiotic resistance and the vulnerability of the HIV/AIDS-immunocompromised to opportunistic pathogens are well-documented medical crises ,23,24,25In our current SEIR model, we examine the evolutionary impact of resistant strain emergence and circulation within a highly HIV/AIDS-prevalent host population. The results of this model highlight an additional reason why analyses of the probability of emergence of antibiotic resistance should include the consideration of population-wide HIV/AIDS prevalence: widespread use of medically recommended antibiotic prophylaxis is a phenomenon specific to highly immunocompromised host populations . TherefoThe use of antibiotic prophylaxis is known to create an evolutionary tradeoff, wherein despite the potential improvement in host health, a fitness benefit is conferred to resistant bacterial strains . HoweverIn a populations such as Swaziland, in which up to 27.4% of the adult population may be immunocompromised , this meWe note that, without violating our simplifying assumption that immune status remains unchanged over the duration of the model, we are limited in our ability to assess the long-term (>one year) behavior of this system. However, our initial findings suggest that surveillance efforts directed toward examining the prevalence of TB—or any other opportunistic pathogen—alone, without consideration for strain specificity, will fail to capture the impact of HIV/AIDS-related effects, such as the widespread use of antibiotic prophylaxis, on resistant strain emergence and maintenance. Moreover, it is likely that projections regarding TB-attributable morbidity and mortality will be underestimated if the percentage of hosts infected with resistant bacterial strains is not taken into account. Given that these effects were visible within the one-year duration of this model, the potential for long-term resistant-strain dominance creates a public health threat that cannot be ignored.Extending our previous work, we stratify our population based on immune status, including five categories of susceptibles: (1) those who are fully immunocompetent ; (2) those who are HIV+ or AIDS+, but whose opportunistic infection risk is minimized by consistent use of HAART ,30,31; ; * + means infection-positive, completely adherent; * / means infection positive, nonadherent; and * - means infection-positive, untreated. For purposes of this description, we use “*” generically to represent the possibility of infection with either the drug-sensitive or drug-resistant bacterial strain. In the ODE model equations . Finally, we use the subscript - + to describe prophylactically treated susceptibles.Within each immune class, we further delineate our population based on the combination of bacterial infection and adherence to targeted antibiotics. The combined description of immune/HAART and infection/antibiotic status is depicted via super- and subscripts to the variables associated with each compartment of the model. quations , howeverFor HIV/AIDS+ susceptibles initially prescribed antibiotic prophylaxis, we make two conservative assumptions: First, we assume that these susceptibles are completely adherent to their prophylaxis regimens. Second, we assume that those who contract drug-resistant infections while prophylactically treated are then also completely adherent to the targeted antibiotics subsequently prescribed to treat the infection. Therefore, all infectives who have previously been treated prophylactically are assigned to either the + is the probability of immediate infection detection and complete treatment, as defined by DOTS protocol [/ is the probability of partial adherence, wherein the host received antibiotics for some period of time during infectivity, but did not follow dosing instructions; and C- is the probability that the host failed to seek treatment.Particularly in the developing world, many demographic and economic factors influence host antibiotic adherence ,37,38,39protocol ; C/ is t−6 for drug-resistant TB among immunocompetent hosts. We adjusted Cohen and Murray’s rate, which was based on an idealized population of one million, to account for the combination of Swaziland’s total population, and the size of each immune status-based subpopulation, and converted it from an annual to a daily rate. In assigning β values associated with both the sensitive and resistant strains, we assume equivalent immune function for the fully immunocompetent and HAART+ categories. We also assume that the actively AIDS-immunocompromised are an arbitrary 10% more likely to contract TB following exposure to an infected individual.d Murray , who proSince data regarding the transmission probability of drug-sensitive TB were not immediately available in the literature, we assigned values to , et al. , and the, et al. . Detailsppear in ,10 and aWe use ϕ to represent the composite probability of the emergence and success of an antibiotic-resistant infection among prophylactically treated susceptibles. Values for ϕ were determined based on the per cell, per bacterial generation mutation rate; the total number of infected cells per host; the expected number of bacterial generations per infection duration; the per category infection duration; and the relative success of the mutant strain ,43,44,45Finally, we use ζ to represent the immune status-based transition rate from latent to active infection. Adapting our values from Cohen and Murray , who theOur model follows the progression of both drug-sensitive and drug-resistant infections throughout a population stratified based on immune status . We use ailed in ,10).Model outcomes were obtained by implementation of the model in the Wolfram Mathematica programming language see .Using HIV/AIDS prevalence data from Swaziland, we address the question of evolutionary fitness in drug-resistant and drug-sensitive bacterial strains when prophylaxis use among the HIV/AIDS-immunocompromised and resistant strain transmission probability are varied .The use of antibiotic prophylaxis has been heavily relied upon as a means of opportunistic infection management among the HIV/AIDS-immunocompromised . HoweverPathogen persistence relies upon the composite probability of host-to-host contact and infection transmission . Host suCohen, et al.  found th


By recycling used glass containers, we are able to recover and reuse their valuable properties, which is a way to preserve the relevant natural resources and lessen environmental burdens. For example, recycled waste glass (in the form of powder) can be used in the production of concrete. This article analyses the effect of waste glass addition on the properties of C12/15, which is used, for example, as concrete bedding material to support road drainage gutters and kerbs. Ground waste glass was used as a filler in the mix, i.e., without decreasing the amount of cement. Brown glass collected as municipal solid waste was used in this research. The research comprised an experiment prepared on the basis of the central composite design. The independent variables included water/cement ratio and the amount of glass powder, expressed as the glass to cement ratio by weight. The adopted research program mainly included the definition of the concrete compressive strength, water absorption and freeze–thaw resistance after 25 and 100 cycles of freezing and thawing. For selected systems, the characteristics of air voids in hardened concrete were also defined. The beneficial effect of ground waste glass added as a filler to the concrete mixture on the strength and durability of concrete was confirmed by the obtained test results. The aspects related to the reuse of waste materials, such as waste glass, in the field of construction have become an increasingly widely explored subject of scholarly articles. Although the amount of waste glass collected and recycled in the EU increases year by year, as demonstrated by the most recent data , there aCurrently, waste glass is used as a raw material for the production of glass fibres used in production of thermal and sound insulation panels, mats, and lagging. For example, a very fine-grained waste glass powder is used to produce expanded glass beads added to wall coatings and mortars. Another waste glass material, namely waste flat glass, is used for the production of glass microspheres .Numerous studies have been conducted on the possibility of using finely ground waste glass as a partial replacement for cement in concrete. A smaller glass particle size led to a higher compressive strength in concrete and compared to fly ash concrete, concrete containing ground glass exhibited a higher strength at both early and late ages . The comThe results of studies on the impact of glass granulate as a substitute for natural aggregate in concrete are known. The addition of 25% and 50% of crushed waste glass sand promotes a significant improvement in strength, and the optimum glass content should be 25% for the production of sustainable eco-concrete . With thResearchers expect that fly ash and slag may soon become scarce due to their increasing reuse in the production of energy, similarly to other renewable sources. It is, therefore, justified to search for alternative fine-grained materials that could be successfully used in the production of concrete. Ground waste glass can be an option of choice in these circumstances. Other than fly ash or slag, this additive is not a combustion by-product. Moreover, due to the high cost of segregating small-size waste glass items (advanced sorting systems are needed in the process), coloured waste glass seems to be a very promising option in this application. This applies in particular to lower strength classes of concrete , in which various types of waste/by-products coming from various industries have been successfully used for a number of years. The primary applications of this material include bedding under road gutters and kerbs and as a road-base material. It is related to a very wide range of infrastructural investments, which are and will be implemented in Poland for many years.In Poland, road engineers use in the design process the so-called catalogues of standard constructions ,24, whicThe review of the mix specifications of concrete types currently used on the national roads in the West Pomerania province of Poland showed that C12/15 and C16/20 are the prevalent types of concrete mixes. C12/15 concrete is used to support precast gutters at the edges of road pavements and kerbs around the roundabout overrun areas and traversable roundabout islands. C16/20 concrete, in turn, is used much less frequently, predominantly as the base course of pavements in bus lay-by areas. This gives a chance to utilise in this way at least a part of the waste glass sent to landfill. With a vast majority of the research project carried out so far dealing with the use of waste glass as a partial substitute to cement and fine aggregate, the authors have decided to investigate the use ground waste glass as a filler, without decreasing the content of cement in the concrete mixture.As part of the project, an experiment plan was generated in the statistical program Statistica (the “Design of Experiments” module) . A centr1  and x2 . The input values were W/C, in the range of 0.73–0.87 and GP/C, which was in the range of 0% to 45%. Nine series of specimens were produced, differentiated by the concrete mix composition. The studies were carried out for five intermediate values of input data x1 and x2 determined for standardised values equal to 0, ±1 and ±1.414. The standardised values resulting from the adopted plan were calculated into real values of variables. The coded variables and the compositions of the respective series of specimens in the adopted experiment plan are compiled in The tests were carried out on concrete mixes based on natural aggregate for five intermediate input values xThe constants were the type and class of cement, fine and coarse aggregate types, method of adding the ingredients, mixing method and time and method of compacting fresh concrete, curing time, and curing conditions and, last but not least, the test apparatus.3 and the density of cement was 3.102 g/cm3. The Blain air permeability test was used to measure the specific surface area and ground glass was found to have a greater specific surface than cement (4737 cm2/g compared to 3728 cm2/g).Brown glass was chosen for this experimental research. It was cleaned and dried and then crushed and powdered . The iniThe compositions of prepared mixes are given in The mix included 200 kg of Portland cement CEM I 42.5R manufactured by Cemex Gdynia, in which cement clinker was the only cementitious material . Fine-grained aggregate was 0/2 mm sand from Bielinek sand and gravel pit. The percentage of sand contained in the aggregate mix was 50.6%. Additionally, 2/8 mm and 8/16 mm gravels from Ognica pit were used as coarse aggregate.Consistency, determined with the slump cone test according to EN 12350-2 ;Air content determined with the pressure gauge method according to EN 12350-7 ;Density according to EN 12350-6 .The prepared concrete mixes were tested for the basic properties including:The results of concrete mix tests are given in 3 and 2273 kg/m3. Taking into consideration the measurement uncertainties, one can conclude that the addition of glass powder with an identical water/cement ratio does not impact the concrete mix air content and its consistency. The differences in the results of air content and concrete mix density are comparable and smaller than the measurement uncertainty.The consistency and air content were measured once, 15 minutes after water was added to the mix. Two of the tested mixes, namely PW4 and PW6, attained S2 consistency and the other ones fell in the consistency class S1. The total air content in the mixes ranged from 4.0–5.1%. The density of concrete mix oscillated between 2219 kg/m1 (W/C) and x2 (GP/C) are given in parentheses next to the concrete mix symbol.Out of each concrete mix, a series of six specimens was created for determining the compressive strength. To determine the strengths of the specimens, compression testing machines  were used. Compressive strength was determined after 7 and 28 days of curing the specimens in water at the temperature of 20 ± 2 °C. The tests were carried out on three 150 mm cubes, according to the procedure described in EN 12390-3 . The FigThe compressive strength results varied strongly, in the range of 18.1–29.9 MPa. The assumed compressive strength to satisfy the requirement of the C12/15 strength class according to EN 206 after curing for 28 days  was obtaFrom the analysis of the 7 day and 28 day compressive strength values, it follows that the increase in strength of the control concrete mix by 25.1% was much smaller than that obtained for the mix containing waste glass. The highest levels of strength increase, viz. from 30.5% to 51.9%, were noted for the mixes containing waste glass. As we have observed, with the same water-to-cement ratio, the higher the proportion of waste glass, the higher the increase in the compressive strength of the mix.Water absorption of the tested mixes was determined according to PN-B-06250:1988 . Four 10According to the obtained water absorption test results, the absorption criterion, as per PN-S-96014:1997 , was satFreeze–thaw resistance of concrete was tested according to PN-B-06250:1988  with theBased on the frost resistance criteria of PN-B-06250:1988 , the weiThe freeze–thaw resistance criteria were satisfied by all the mixes subjected to a standard procedure  comprisiOther than in the case of 25 freeze–thaw cycles, 100 cycles caused an average increase in the specimen weight by 0.3%. Furthermore, the higher number of cycles caused a greater decrease in the compressive strength, namely by 3.0 to 45.0%. Only two mixes showed no observable distress: PW2 and PW5 b. By satDefining the characteristics of air voids in hardened concrete was carried out in accordance with the EN 480-11:2008 standard . SpecimeL (the average distance to the nearest air void), which should not be larger than 0.2 mm. Another, also important parameter is the minimum air content in air voids smaller than 0.3 mm, marked as 300A, which should equal at least 1.5%. The data obtained as a result of the automatic analysis of the image from four specimens of the surface from each spacing of concrete air voids selected for the analysis allowed for calculating the total content of air (A), the specific surface area of the air voids (α), the air void spacing factor (L) and the content of micro-air-voids with a diameter lower than 0.3 mm (300).A The obtained average values of the analysed parameters, defined according to the standard [Concretes marked as PW5, PW8 and PW9 contain the addition of glass powder and demonstrate significant compressive strength and resistance to cyclical freezing and thawing. Concrete marked as PW7, in turn, is control concrete, which does not include the addition of glass powder. It meets the minimum requirements associated with the concrete strength class, but it does not meet the requirement of the F100 degree of freeze–thaw resistance. The most frequently adopted parameter for the assessment of the freeze–thaw resistance of concretes is the air void spacing factor standard , in part−1. Differentiated results were obtained for the total air content, unlike the results of the analysis of air content in the concrete mix, defined using the pressure method (from 5.8% to 13.2%). The total air content in the hardened concrete fits within the range of 10.9–18.2%. Such a high air content is probably the result of the insufficient compacting of the specimens. The highest value of the air void spacing factor (L) and the lowest content of micro-air-voids (300A) were demonstrated by the concrete marked as PW8, which included the highest amount of the addition of glass powder. In the case of an identical water/cement ratio equal to 0.80, one can notice that in concrete PW8, along with the increase in the amount of glass powder (from 22.5% to 45.0%), there was a decrease in the total content of air and micro-air-voids (300A); whereas in concrete marked as PW5, with the water/cement ratio lower than in concrete PW9 , one observes lower total content of air and of air voids with a diameter lower than 0.3 mm and a lower specific surface area of the air voids (α). While analysing the achieved results of marking the characteristics of the air void spacing in selected concretes , it is possible to conclude that they meet the requirements in reference to concrete utilized in XF conditions. According to the standard , concretFor the purpose of designating the spacing of air voids, a calculation model was adopted, which assumes the occurrence of air voids of a certain determined diameter. It is a transitional model between the actual state and Powers’ model. The measured chords are classified into appropriate length ranges, and subsequently, the number of chords in a given length class is determined and multiplied by the volume of a single air void with the diameter equal to the top limit of a given class. The size distribution of air voids recorded during the study conducted on four specimens has been presented in As was demonstrated in the distribution of air content as a function of the air void diameter  in hardep). The variance equality hypothesis was also found to be true through the Levene and Brown–Forsyth tests. The analysis of data also included checking the significance of the effect of input data (W/C and GP/C) on the values of the output variable (28 day compressive strength). The Fisher–Snedecor test was employed for this. The values of significance levels p below 0.05 indicate a significant effect of the water–cement ratio and the amount of added glass powder (in relation to the weight of cement) on the 28 day compressive strength of the tested mixes. In the further part of the statistical analysis, a model representing the effect of independent variables on the 28 day compressive strength was built on the basis of the output data of the experiment carried out according to the central composite design. A linear-quadratic model with two-way interactions was adopted in the first place. Insignificant components were then left out one by one through the analysis of the results in Statistica [The results were subjected to a statistical analysis in the software program Statistica . First, atistica . FinallyThe regression function was verified on the standardised values iA (regression coefficient) of this equation were obtained with the Gauss–Newton method of estimation. Using the t-Student test factors, 2A, 4A and 5A were excluded as insignificant at the significance level of 0.05. The correlation factor R was 0.96. In the case of two input data values (W/C and GP/C), it is possible to develop the contour diagram that presents the response surface of the object of studies. The values of the predicted 28 day compressive strength are given in The constants Linear relationships were obtained between the 28 day compressive strength and both of the analysed parameters, i.e., waste glass to cement ratio by weight and the water–cement ratio. From the results of the statistical analysis of the mechanical parameters obtained in the tests, it can be seen that the compressive strength increased with the increasing proportion of glass powder and the decreasing level of the water–cement ratio. The tests confirm how strongly the compressive strength depends on the water–cement ratio of the concrete mix. Within the analysed ranges, the effects of glass powder and water–cement ratio on the freeze–thaw durability of concrete are not statistically significant.Improves the 28 day compressive strength by ca. 20% and 40% when added at the proportions of 22.5% and 45%, respectively;Does not increase water absorption;Improves the freeze–thaw durability of concrete (without the presence of de-icing agents), which is testified by compliance with the requirements given for F100 concretes designated PW8–PW10.Glass powder changes the properties of low-strength concrete mixes (as compared to the control mix PW7 with the same water–cement ratio and without ground waste glass addition) as follows:Except for PW3 and PW6, all of the tested mixes satisfied the requirements of  in termsMixes PW2 and PW5, in addition to the above-mentioned requirements, also satisfy the compressive strength, water absorption and freeze–thaw resistance criteria defined for concrete class F25 in the Polish standard no. PN-S-96014:1997 , and thuThe average parameters of the microstructure of air voids according to the standard  in speciThe tests carried out as part of this research and the analysis of the obtained result allow us to draw the following conclusions:Therefore, it is possible to produce lower strength concrete mixes containing ground waste glass in the role of filler, i.e., not as a partial substitute to cement. It remains to say, based on the study results, that the prospects for recycling waste glass as a component of concrete mixes are promising. This opinion must, however, be verified by further testing, especially using higher strength mixes. Such verification should cover, in particular, the durability of concrete, including resistance to the action of de-icing salts.