Journal of Antimicrobial Chemotherapy最新文献

{"title":"To be or not to be: the non-antimicrobial properties of common antimicrobials.","authors":"Shivakumar Narayanan, Laura Sneller, Poonam Mathur","doi":"10.1093/jac/dkaf150","DOIUrl":"https://doi.org/10.1093/jac/dkaf150","url":null,"abstract":"<p><p>Antibiotics are diverse in their utility in clinical care. They are widely prescribed for their antimicrobial effect and used as modulators, although rarely, of non-infectious conditions, to influence immune responses, to decrease morbidity and improve quality of life. This review provides a concise summary of different classes of antibiotics and their unique properties that allow them to be used in the treatment of non-infectious conditions.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":" ","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144078279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In vitro activity of NOSO-502, a novel-action antimicrobial, against clinical strains of Enterobacterales including MDR strains.","authors":"Marie L G Attwood, Alan Noel, Pippa Griffin, Emilie Racine, Maxime Gualtieri, Alasdair MacGowan","doi":"10.1093/jac/dkaf152","DOIUrl":"https://doi.org/10.1093/jac/dkaf152","url":null,"abstract":"<p><strong>Background: </strong>NOSO-502 belongs to a new class of cationic peptide antimicrobials-the odilorhabdins-which have a novel mechanism of action inhibiting protein synthesis. NOSO-502 is in preclinical development for the treatment of difficult-to-treat MDR Gram-negative infections.</p><p><strong>Methods: </strong>A total of 360 Enterobacterales were tested against NOSO-502 and comparators using the ISO reference microdilution method. The test panel was derived from clinical isolates and enriched with MDR strains including carbapenemase producers. Time-kill experiments were performed with NOSO-502 and two comparator agents over 24 h at MIC×1 to MIC×16 concentrations.</p><p><strong>Results: </strong>NOSO-502 demonstrated potent in vitro activity against Escherichia coli (MIC50/90 2/4 mg/L), Klebsiella pneumoniae (MIC50/90 0.5/1 mg/L), Enterobacter spp. and Citrobacter spp. strains (both MIC50/90 1/2 mg/L). MIC50/90 values for Proteus mirabilis were >64/>64 mg/L. None of ESBL production, meropenem non-WT susceptibility, MDR phenotype or the presence of NDM, KPC, OXA, IMP or VIM carbapenemases impacted on the activity of NOSO-502. In time-kill curves, NOSO-502 showed concentration-dependent killing of E. coli, Klebsiella spp. and C. freundii.</p><p><strong>Conclusions: </strong>NOSO-502 showed potent in vitro inhibitory and bactericidal activity against a panel of Enterobacterales enriched for resistant phenotypes for which there are few therapeutic choices. These findings need to be placed in context with the appropriate pharmacokinetic and dynamic characteristics of NOSO-502.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":" ","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144078277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Decline of antimicrobial resistance in Pseudomonas aeruginosa bacteraemia following the COVID-19 pandemic: a longitudinal observational study.","authors":"Yulia Butscheid, Pascal M Frey, Marc Pfister, Lisa Pagani, Roger D Kouyos, Thomas C Scheier, Willy I Staiger, Stefano Mancini, Silvio D Brugger","doi":"10.1093/jac/dkaf136","DOIUrl":"https://doi.org/10.1093/jac/dkaf136","url":null,"abstract":"<p><strong>Background: </strong>Understanding the effects of changes brought by the COVID-19 pandemic on antimicrobial resistance in P. aeruginosa (PA) is essential to inform clinical management.</p><p><strong>Methods: </strong>This single-centre retrospective cohort study included adult inpatients with PA bacteraemia at the University Hospital Zurich between January 2014 and December 2023. The primary outcome was the association between the start of the COVID-19 pandemic and PA with multidrug resistance (MDR), defined as resistance to ≥3 of 5 antibiotic classes. We used logistic regression to adjust for age, sex and ICU treatment. Secondary outcomes included changes in resistance patterns, patient demographics and antimicrobial consumption.</p><p><strong>Results: </strong>A total of 493 instances of PA bacteraemia in 333 patients were observed during the study period. The proportion of MDRPA declined from 21% (62/291) pre-pandemic to 9% (19/202) post-pandemic (adjusted OR 0.38, 95% CI 0.18-0.79, p = 0.01). The occurrence of MDRPA during hospitalization following an initial instance of non-MDRPA bacteraemia was rare and unlikely to happen earlier than after 2 weeks. After the start of the pandemic, we observed no MDRPA cases involving cardiovascular or pulmonary diseases and marked reductions in patients with burn injuries or organ transplants. Furthermore, ciprofloxacin and tobramycin use significantly decreased after the start of the pandemic. Overall in-hospital mortality among patients with MDRPA bacteraemia remained high (28%), with no substantial differences between time periods.</p><p><strong>Conclusion: </strong>We observed a decline in MDRPA occurrence after the start of the COVID-19 pandemic, possibly driven by intensified infection control measures, shifts in antimicrobial use and changes in patient populations.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":" ","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144025961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Early use of the novel antifungal rezafungin: a case series and literature review.","authors":"H C Davidson, T Yau, I Dunstan, A Houston, M Basarab, T Bicanic","doi":"10.1093/jac/dkaf143","DOIUrl":"https://doi.org/10.1093/jac/dkaf143","url":null,"abstract":"<p><strong>Objectives: </strong>Rezafungin is a novel echinocandin with a unique structural configuration enabling weekly IV dosing. We report on early use of rezafungin in our outpatient parenteral antibiotic therapy (OPAT) service, reviewing indications, treatment regimens, outcomes and adverse events in adult patients receiving rezafungin at a tertiary infectious disease centre. We also review published cases of rezafungin use, licensing trials, spectrum and pharmacokinetics/pharmacodynamics and how that might relate to its propensity to generate resistance (in comparison with daily echinocandins).</p><p><strong>Methods: </strong>All adult patients who received rezafungin therapy via the OPAT service in 2024-25 were included. Patient demographics, infections, treatment regimens and outcomes were recorded.</p><p><strong>Results: </strong>Six patients (age range 30-84 years) received rezafungin therapy between July 2024 and February 2025. Indications included invasive and mucocutaneous candidiasis, predominantly caused by azole-resistant Candida species. We also report the first case of using rezafungin in combination with voriconazole to treat azole-refractory pulmonary aspergillosis. Rezafungin courses were a median length of 4 doses (range: 2-5) and were generally well tolerated with no laboratory adverse events. Reasons for choosing rezafungin over daily echinocandins were patient preference/convenience (n = 5), concern regarding azole resistance (n = 4) and facilitation of earlier discharge (n = 2). One hundred and fifty-seven days with an IV catheter were saved through once-weekly dosing. Outcomes were positive, with all patients showing mycological clearance.</p><p><strong>Conclusions: </strong>Early use of rezafungin at our centre and in the international literature suggests it is a well-tolerated, convenient and useful addition to the antifungal armamentarium, particularly in the outpatient setting.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":" ","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144016348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimal dosing of amoxicillin in obese and post-gastric bypass patients using a population pharmacokinetics-pharmacodynamics model approach.","authors":"Gisela Myrian de Lima Leite Dalla Rosa, Priscila Akemi Yamamoto, Maria Madalena Corrêa Melo, Gustavo F Sakamoto, Maiara C Montanha, Paulo Paixão, Andréa Diniz, Natália Valadares de Moraes, Elza Kimura","doi":"10.1093/jac/dkaf144","DOIUrl":"https://doi.org/10.1093/jac/dkaf144","url":null,"abstract":"<p><strong>Aim: </strong>To characterize the impact of obesity and Roux-en-Y gastric bypass (RYGB) on systemic exposure to amoxicillin using population modeling approach. We also performed simulations to provide insights into optimising the dosing of amoxicillin against infectious bacteria in the respiratory tract.</p><p><strong>Methods: </strong>Non-obese, obese, and post-RYGB patients, aged between 24 and 50 years, from two clinical studies, were evaluated. Sex, age, body size descriptors, history of bariatric surgery and renal function were assessed as potential covariates. The percentage of time of unbound amoxicillin plasma concentration above the minimum inhibitory concentration (%fT > MIC) of >40%, representing bactericidal activity, was used as a PK/PD target to calculate the probability of target attainment (PTA). The PTA threshold was defined as 90% of treated individuals achieving fT > MIC ≥ 40%.</p><p><strong>Results: </strong>Amoxicillin PK was best characterized by a one-compartment model including a zero-order absorption with lag time followed by a first-order absorption and linear elimination. The relative oral bioavailability in post-RYGB patients was nearly halved compared with non-obese subjects. Age exhibited a negative correlation with clearance, consistent with amoxicillin being a hydrophilic drug primarily eliminated through the kidneys. For MIC ≤ 2 mg/L, the oral dosing regimen of 1000 mg q6h reached the therapeutic target for non-obese. For MIC ≤ 1 mg/L, 1000 mg q6h is needed in obese and post-RYGB subjects.</p><p><strong>Conclusion: </strong>Amoxicillin doses of 1000 mg q6h were found to maximize the probability of attaining the PK/PD target with MIC ≤ 1 mg/L in obese and post-RYGB patients.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":" ","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143972225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Population pharmacokinetics and thrombocytopenia risk assessment of linezolid in liver transplant recipients.","authors":"Xiaoping Shi, Wenyu Yang, Fanyu Zhao, Donghui Lao, Qing Xu, Xiaoyu Li, Qianzhou Lv, Qingfeng He, Xiaoqiang Xiang, Ting Wang, Xiao Zhu","doi":"10.1093/jac/dkaf147","DOIUrl":"https://doi.org/10.1093/jac/dkaf147","url":null,"abstract":"<p><strong>Background: </strong>Linezolid is a commonly prescribed antibiotic for multidrug-resistant enterococcal infections in liver transplant recipients (LTRs). However, changes in pharmacokinetics due to fluctuations in liver and renal functions, combined with the increased risk of thrombocytopenia, complicate its clinical use. This study aimed to characterize the exposure-thrombocytopenia risk relationship of linezolid in LTRs, and to identify safe dosing thresholds to promote rational drug use.</p><p><strong>Methods: </strong>A retrospective analysis was conducted on adult LTRs treated with linezolid at Zhongshan Hospital between January 2019 and May 2022. A population exposure-safety model was developed and used to establish a thrombocytopenia risk threshold and optimize initial dosing strategies through Monte Carlo simulations. An area under the concentration-time curve (AUC) calculator was developed to facilitate individualized dose adjustments.</p><p><strong>Results: </strong>Exposure-safety analysis revealed that an AUCss,24h threshold of 291.7 mg/L·h was associated with an increased risk of thrombocytopenia. Monte Carlo simulations showed that current covariate-based initial dosing recommendations were suboptimal, highlighting the necessity of therapeutic drug monitoring (TDM) to improve outcomes in LTRs. The online AUC calculator developed in this study offers a practical tool for clinicians to implement timely dose adjustments (https://optimaldose.shinyapps.io/LinezolidAUC/).</p><p><strong>Conclusions: </strong>This study provides the first comprehensive analysis of linezolid exposure and its relationship to thrombocytopenia risk in LTRs. The findings underscore the importance of AUC-guided dosing and TDM in optimizing treatment outcomes.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":" ","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143972032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The role of antimicrobial prophylaxis in brachytherapy for prostate, breast and gynaecological cancer: a narrative review.","authors":"Konstantinos Alexakis, Iosif Strouthos, Aris P Agouridis, Konstantinos Ferentinos, Constantinos Zamboglou, Nikolaos Spernovasilis","doi":"10.1093/jac/dkaf139","DOIUrl":"https://doi.org/10.1093/jac/dkaf139","url":null,"abstract":"<p><p>Proper antimicrobial prophylaxis is critical for reducing the risk of infection during interventional procedures. Brachytherapy, a highly effective radiation therapy for various malignancies, allows for precise radiation delivery; however, the use of foreign material as instrumentation for brachytherapy potentially increases the risk of infection. Understanding infectious complications and proper antimicrobial use in this case is essential for successful outcomes and patient safety. The aim of this review is to provide insights and summarize existing information on the infectious complications of brachytherapy in prostate, breast and gynaecological (cervical and endometrial) cancer, as well as on the potential benefit, if any, of administering antimicrobial prophylaxis. Infectious complication rates in prostate, breast and gynaecological cancer brachytherapy remain low with diverse prophylactic regimens, emphasizing the need to identify risk factors for tailored practices. The choice of the antimicrobial regimen, type of device and modality influences the probability of infectious complications. There is minimal overlap of existing brachytherapy guidelines with surgical prophylaxis guidelines. Infectious outcomes and antimicrobial resistance are underreported, and guidance for antimicrobial-resistant organisms is scarce. When indicated, prophylaxis for less than 24 h is efficient. More studies oriented towards antimicrobial prophylaxis on this specific population are needed.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":" ","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144010822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Selected comorbidities and the probability of ART switch in PWH with undetectable HIV-RNA: a retrospective analysis in Italy.","authors":"Alessandro Cozzi-Lepri, Alessandro Tavelli, Lucia Taramasso, Giuseppe Lapadula, Nicoletta Bobbio, Stefania Piconi, Giovanni Guaraldi, Antonio Di Biagio, Antonella Castagna, Valentina Mazzotta, Antonella d'Arminio Monforte","doi":"10.1093/jac/dkaf137","DOIUrl":"https://doi.org/10.1093/jac/dkaf137","url":null,"abstract":"<p><strong>Objectives: </strong>To estimate the incidence of comorbidities in persons with HIV (PWH) with a stable viral load (VL) of ≤50 copies/mL and evaluate the likelihood of treatment switch (TS) according to the new development of dyslipidaemia (DP), kidney disease and a weight change that determined overweight.</p><p><strong>Methods: </strong>We carried out six case-control studies nested within the Icona Foundation Study cohort with the outcome of TS of the current regimen (due to intolerance/toxicity or simplification) and investigated the incident comorbidities. Conditional logistic regression models were employed.</p><p><strong>Results: </strong>Overall, the median age of study participants was 45 years (IQR: 36-52), 19% were female, 48% were MSM and 17% were migrants. DP was confirmed to be the most frequent incident comorbidity [138 events; incidence rate (IR) = 28.4%; 95% CI: 22.7%-34%], followed by estimated glomerular filtration rate (eGFR) deterioration and BMI elevation. None of the studied factors was associated with the risk of TS because of simplification. TS because of toxicity was predicted by incident DP [adjusted OR (aOR) = 2.49, 95% CI: 1.19-5.19, P = 0.02] and by a decline in eGFR of >10 mL/min/1.73 m2 (aOR = 1.51, 95% CI: 0.98-2.32, P = 0.06). The association with DP was stronger in participants who were receiving a boosted PI-based regimen at baseline (aOR = 3.38, 95% CI: 1.11-10.30, P = 0.03). Therapy discontinuation because of toxicity/simplification has remained common in PWH with VL of ≤50 copies/mL in recent years.</p><p><strong>Conclusions: </strong>The onset of DP and a decline in eGFR was associated with discontinuations due to toxicity. Interventions aiming to mitigate the risk of developing lipid abnormalities in PWH are likely to also reduce the number of ART changes, which can potentially affect future drug options.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":" ","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144019057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Model-based translation of the PKPD-relationship for linezolid and vancomycin on methicillin-resistant Staphylococcus aureus: from in vitro time-kill experiments to a mouse pneumonia model.","authors":"Diego Vera-Yunca, Carina Matias, Carina Vingsbo Lundberg, Lena E Friberg","doi":"10.1093/jac/dkaf140","DOIUrl":"https://doi.org/10.1093/jac/dkaf140","url":null,"abstract":"<p><strong>Objectives: </strong>MRSA is one of the main pathogens that cause nosocomial pneumonia. Based on longitudinal in vitro and in vivo data, a pharmacokinetic-pharmacodynamic (PKPD) model was built to quantify the effect of two control antibiotics (LZD and VAN) for Gram-positive bacteria in a standardized mouse pneumonia model.</p><p><strong>Methods: </strong>The PKPD model was developed for data generated on the MRSA strain 160 079 in static in vitro time-kill experiments and thereafter adjusted to fit data from lungs of neutropenic mice administered with single or multiple doses of LZD (0.5-40 mg/kg) or VAN (1-40 mg/kg). Simulations with human PK were run to predict antibacterial response in patients.</p><p><strong>Results: </strong>Bacterial regrowth observed in vitro when exposed to VAN concentrations was described by an adaptive resistance model. The selected MRSA isolate showed good virulence in the mouse pneumonia model. Bacterial load in lungs decreased up to 2-log with respect to control mice after LZD and VAN treatment. A 70%-75% lower killing rate was estimated for the in vivo data when compared with in vitro. Simulations displayed bacterial stasis at 24 h for patients infected with bacteria with MICs below the clinical breakpoint for both drugs after administering standard-of-care dosing regimens.</p><p><strong>Conclusions: </strong>A translational workflow allowed us to build a PKPD model with both in vitro and in vivo data that characterized bacterial dynamics following LZD and VAN exposure, showing that this approach can inform the development of antibiotics. We also showcased the first successful use of the standardized mouse pneumonia model for Gram-positive bacteria.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":" ","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144005208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Antibiotic use attributable to RSV infections during infancy-an international prospective birth cohort study.","authors":"Sarah F Hak, Roderick P Venekamp, Marie-Noëlle Billard, Daniela Cianci, Marlies A Van Houten, Andrew J Pollard, Terho Heikkinen, Steve Cunningham, Margaret Millar, Federico Martinon-Torres, Ana Dacosta-Urbieta, Louis J Bont, Joanne G Wildenbeest","doi":"10.1093/jac/dkaf123","DOIUrl":"https://doi.org/10.1093/jac/dkaf123","url":null,"abstract":"<p><strong>Background: </strong>Early-life antibiotic use impacts microbiome composition and contributes to the emergence of antimicrobial resistance. Despite respiratory syncytial virus (RSV) being a leading cause of acute respiratory infections (ARI), accurate estimates of antibiotic use attributable to RSV are lacking.</p><p><strong>Objectives: </strong>To assess RSV-associated antibiotic use during the first year of life.</p><p><strong>Patients and methods: </strong>The RESCEU birth cohort study followed healthy term infants, born (n = 9154) between 1 July 2017 and 31 July 2020 from five European countries, to identify RSV-ARI hospitalizations during infancy. In a nested cohort (n = 993), we performed active RSV surveillance by collecting nasal swabs in case of ARI symptoms during RSV seasons (October-April). Antibiotic use during hospitalization was identified through chart review, while outpatient data were collected via parental questionnaires.</p><p><strong>Results: </strong>In the total cohort, antibiotics were used in 22.8% of RSV hospitalizations (33/145) and 62.5% of RSV intensive care admissions (5/8). In the nested cohort, antibiotics were used in 5.2% of any-severity RSV-ARI (13/250) and 9.9% of medically attended RSV-ARI (13/131). This results in an estimated incidence of 1.3% (95%CI: 0.8-2.0) of healthy term infants receiving ≥1 course of antibiotics associated with RSV infection in their first year, with an incidence rate of 1.1 RSV-associated antibiotic prescriptions per 1000 infant-months (95%CI: 0.6-1.9). As such, RSV accounts for 22.9% of antibiotic prescriptions for ARI during RSV seasons.</p><p><strong>Conclusions: </strong>One in 77 healthy term infants receives antibiotics during RSV infection before their first birthday. Real-world evidence is needed to establish the impact of RSV immunization on antibiotic use during infancy.</p><p><strong>Clinical trials registration: </strong>NCT03627572.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":" ","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143972143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}