Journal of Antimicrobial Chemotherapy最新文献

{"title":"Tigecycline displays bactericidal activity against multidrug-resistant Neisseria gonorrhoeae and enhances clearance from a mouse infection model.","authors":"Xia Sun, Wenyan Lu, Haoyu Ge, Yuling Qin, Dailin Yuan, Xu'ai Lin, Yuefeng Rao, Stijn van der Veen","doi":"10.1093/jac/dkag337","DOIUrl":"https://doi.org/10.1093/jac/dkag337","url":null,"abstract":"<p><strong>Objectives: </strong>The global emergence of ceftriaxone-resistant Neisseria gonorrhoeae threatens current first-line treatment and necessitates alternative therapeutic options. Tigecycline, a last-line glycylcycline antibiotic approved for complicated infections, was evaluated for repurposing against N. gonorrhoeae through in vitro and in vivo activity studies.</p><p><strong>Methods: </strong>Antimicrobial susceptibility testing was performed for 616 clinical isolates (2011-2024) from Hangzhou, China, and bactericidal activity was determined in time-kill assays. A mouse vaginal tract infection model was used to evaluate in vivo tigecycline activity. Chequerboard assays were performed to assess interactions between tigecycline and ceftriaxone.</p><p><strong>Results: </strong>Tigecycline demonstrated potent activity (MIC50: 0.125 mg/L; MIC90: 0.25 mg/L), including against tetracycline-resistant (tetracycline MIC50: 2 mg/L; MIC90: 64 mg/L) and high-level ceftriaxone-resistant (ceftriaxone MIC50: 0.03 mg/L; MIC90: 0.125 mg/L) strains. Time-kill assays (2 strains) revealed concentration-dependent bactericidal activity, with 4×MIC achieving ≥105-fold killing. In the mouse vaginal tract infection model, high-dose tigecycline (25 mg/kg) significantly enhanced bacterial clearance, eliminating infection within 3-6 days compared to 8-12 days in vehicle controls, and substantially reduced bacterial burden. Chequerboard assays against 21 isolates (10 ceftriaxone-susceptible, 11 ceftriaxone-resistant) demonstrated indifferent interactions between tigecycline and ceftriaxone (fractional inhibitory concentration indices 1.03-2.56), indicating no antagonism.</p><p><strong>Conclusions: </strong>These findings establish that tigecycline exhibits potent, rapid bactericidal activity against N. gonorrhoeae, including against high-level ceftriaxone-resistant strains, with robust in vivo efficacy. They support further investigation of tigecycline as a potential repurposing candidate for multidrug-resistant gonorrhoea, although its clinical role remains to be defined.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":"81 11","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149127566","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":"Oxazolidinones in the Clinical Management of Staphylococcal Infection-Linezolid or Tedizolid? A review on behalf of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for Staphylococci and Staphylococcal Diseases (ESGS).","authors":"Liana Macpherson, Anne-Grete Martson, Jose L Del Pozo, Cindy Zheng, Anna L Goodman","doi":"10.1093/jac/dkag323","DOIUrl":"10.1093/jac/dkag323","url":null,"abstract":"<p><p>There is limited information in the existing literature regarding the choice of oxazolidinone in clinical practice to treat infections caused by staphylococcal species. As members of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for Staphylococci and Staphylococcal Diseases (ESGS) we have collaborated and written this narrative review aimed at clinicians considering these agents in practice. The review focuses on two medications, linezolid and tedizolid, with a comprehensive description of pharmacology aspects, adverse effects, drug interactions and contraindications, and we investigate the potential for treatment optimization. We anticipate that this article will provide support for those considering utilization of linezolid and tedizolid in clinical practice to treat staphylococcal species.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":"81 11","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13655609/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149166118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benzylpenicillin exposure during veno-venous extracorporeal membrane oxygenation: pre- and post-oxygenator levels in a case report.","authors":"Lieke van Gastel, Eva van Haren, Tim Smeets, Jan Elderman, Nicole Hunfeld","doi":"10.1093/jac/dkag333","DOIUrl":"https://doi.org/10.1093/jac/dkag333","url":null,"abstract":"","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":"81 11","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149194046","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":"HIV-1 integrase inhibitor resistance in viraemic-treated individuals and baseline capsid diversity relevant to future lenacapavir therapy.","authors":"Adam Abdullahi, Sophia Osawe, Haruna Wisso, Martin Edun, Grace Adebisi, Judith Arachie, Chinedu Ude, James Onyemata, Suleiman Yusuf Alhaji, Yusuf Bara Jibrin, Alash'le Abimiku, Steven A Kemp, Ravindra K Gupta","doi":"10.1093/jac/dkag300","DOIUrl":"10.1093/jac/dkag300","url":null,"abstract":"<p><strong>Background: </strong>Dolutegravir (DTG)-based antiretroviral therapy has been widely adopted across sub-Saharan Africa, yet resistance pathways in non-B HIV-1 subtypes remain poorly defined. As lenacapavir (LEN), a long-acting capsid inhibitor, is introduced for prevention and treatment, characterizing baseline capsid variation alongside emerging integrase resistance is increasingly important. Whether DTG resistance pathways coexist with known capsid resistance mutations in West African epidemics remains poorly described.</p><p><strong>Methods: </strong>We performed deep sequencing of 87 HIV-1 samples from adults (n = 47) and paediatric participants (n = 40) failing DTG-based antiretroviral therapy in Nigeria. Resistance mutations were interpreted using Stanford HIVdb and IAS-USA criteria, with resistance estimates based on gene- or drug-panel-specific denominators. Low-frequency variants were assessed at 2%, 5%, 10% and 20% read-frequency thresholds. Capsid mutations associated with LEN resistance were characterized, structurally mapped and compared to global sequence data. HIV-1 subtype and recombinant forms were assigned using COMET HIV-1 v2.4.</p><p><strong>Results: </strong>At consensus, predicted resistance to ≥1 integrase strand transfer inhibitor (INSTI) was detected in 13/50 integrase-genotypable participants (26.0%; 95% CI 15.9%-39.6%), including 5/50 with a major INSTI resistance mutation. Reduced predicted susceptibility specifically to DTG was present in 6/50 (12.0%; 95% CI 5.6%-23.8%). G118R was detected in 4/50 participants at consensus, while Q148H/K/R and N155H were absent. In exploratory deep-sequencing analysis, G118R was detected in 8/47 participants with sufficient codon-level coverage at the ≥20% read-frequency threshold. No known primary LEN resistance mutation was detected among 33 participants with complete coverage of all six primary resistance positions (0/33; 95% CI 0%-10.4%); T107A, a polymorphic capsid substitution of uncertain effect on LEN susceptibility, was detected in in 3/33 individuals where sequence could be evaluated.</p><p><strong>Conclusions: </strong>These findings demonstrate DTG resistance in both adult and paediatric participants with virological failure with G118R emerging as a prominent resistance pathway. No known primary LEN resistance mutation was detected in the assessable capsid sequences, although phenotypic susceptibility and clinical outcomes were not evaluated. These findings support continued surveillance of integrase and capsid resistance as long-acting antiretroviral strategies expand.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":"81 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13551618/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148906308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A prospective pharmacokinetic interaction study between rifampicin and fusidic acid for the treatment of staphylococcal infections.","authors":"Callum Maggs, Laurens Manning, Okhee Yoo, Sam Salman, Madhu Page-Sharp, Craig Aboltins","doi":"10.1093/jac/dkag293","DOIUrl":"10.1093/jac/dkag293","url":null,"abstract":"<p><strong>Objective: </strong>Fusidic acid with rifampicin is used for the treatment of severe staphylococcal infection, particularly prosthetic joint infections. Previous studies using twice daily fusidic acid showed rifampicin increases fusidic acid clearance, potentially causing sub-therapeutic concentrations. It is uncertain whether this occurs with three-times daily dosing. This study sought to re-evaluate this potential drug-drug interaction.</p><p><strong>Methods: </strong>In this prospective, open-label drug-drug interaction population pharmacokinetic (PK) study, participants were randomized to receive fusidic acid or rifampicin for 24 hours, followed by combination therapy for the duration of treatment. Drug concentration assays used liquid-chromatography mass spectroscopy on dried blood spots. Population PK models were built for fusidic acid, rifampicin and 25-desacetyl rifampicin.</p><p><strong>Results: </strong>Ten participants were recruited. Inter-individual variability for both absorption (98.1%) and clearance (77.8%) were high for fusidic acid. A population pharmacokinetic model for fusidic acid revealed that early autoinhibition dominated over later rifampicin-mediated induction, resulting in a net decrease in fusidic acid clearance. The mean fusidic acid area under the curve during each dosing interval (AUCτ) at steady state was 1.76-fold [0.049, 34.918] higher relative to Day 1, despite high uncertainty.Large inter-individual (110%) variability in absorption was observed for rifampicin. There was no apparent effect on rifampicin metabolism by fusidic acid co-administration, however, fusidic acid decreased clearance of 25-desacetyl rifampicin.</p><p><strong>Conclusion: </strong>In patients treated with fusidic acid three times daily in combination with rifampicin, autoinhibition potentially counteracted rifampicin induction such that fusidic acid concentrations were not reduced. Rifampicin clearance was not affected by fusidic acid, but 25-desacetyl rifampicin clearance was decreased. There was large inter-individual variability in the observed concentrations and final parameter estimates.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":"81 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13550937/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148906211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Antimicrobial activity of aztreonam/avibactam and molecular characterization of Enterobacterales not susceptible to ceftazidime/avibactam and/or meropenem/vaborbactam from US medical centres (2016-2024).","authors":"Helio S Sader, Krisztina M Papp-Wallace, John H Kimbrough, Dmitri Debabov, Rodrigo E Mendes, Mariana Castanheira","doi":"10.1093/jac/dkag308","DOIUrl":"10.1093/jac/dkag308","url":null,"abstract":"<p><strong>Background: </strong>Resistance to ceftazidime/avibactam and meropenem/vaborbactam has been increasing among carbapenem-resistant Enterobacterales (CRE) in US hospitals recently. We evaluated the activity of aztreonam/avibactam and comparators against isolates that were not susceptible to ceftazidime/avibactam and/or meropenem/vaborbactam and against MBL-producing Enterobacterales.</p><p><strong>Methods: </strong>A total of 80 927 Enterobacterales isolates were consecutively collected (one per patient) in 2016-2024 from 103 US medical centres and susceptibility tested by broth microdilution in a monitoring laboratory. Among those, 194 (0.24%) were not susceptible to ceftazidime/avibactam or meropenem/vaborbactam, 115 (0.14%) were not susceptible to both ceftazidime/avibactam and meropenem/vaborbactam, and 832 (1.0%) isolates were carbapenem resistant. These isolates were screened for carbapenemase (CBase) genes by WGS.</p><p><strong>Results: </strong>Aztreonam/avibactam was active against 91.9% of ceftazidime/avibactam-non-susceptible isolates (n = 160), 94.0% of meropenem/vaborbactam-non-susceptible isolates (n = 149), 98.1% of CRE and 98.4% of MBL producers (n = 125). Cefiderocol retained activity against 78.8% of ceftazidime/avibactam-non-susceptible isolates, 83.2% of meropenem/vaborbactam-non-susceptible isolates, 94.7% of CRE and 82.1% of MBL producers. A CBase was identified in 159 (82.0%) of isolates not susceptible to ceftazidime/avibactam or meropenem/vaborbactam and in 683 (80.1%) of CREs. NDM (n = 114; 58.8% of isolates) was the most common CBase type among isolates not susceptible to ceftazidime/avibactam or meropenem/vaborbactam. Notably, an MBL was identified in 36.1% (73/202) of CRE collected in 2023-2024.</p><p><strong>Conclusions: </strong>Aztreonam/avibactam demonstrated potent activity against isolates not susceptible to ceftazidime/avibactam and/or meropenem/vaborbactam as well as against CRE isolates, including MBL producers. The activities of other β-lactamase inhibitor combinations and cefiderocol were adversely affected by the alarming increase of MBL producers in some US hospitals.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":"81 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13531238/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148865330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A multinational genomic framework for predicting β-lactam resistance in Haemophilus influenzae.","authors":"Ala-Eddine Deghmane, Maria Asmi, Sören Abel, Paula Bajanca-Lavado, Heike Claus, Joshua D'Aeth, Ignacio Garcia, Marlena Kiedrowska, Thien-Tri Lam, David Litt, Delphine Martiny, Courtney Meilleur, Anna Skoczyńska, Georgina Tzanakaki, Athanasia Xirogianni, Muhamed-Kheir Taha","doi":"10.1093/jac/dkag307","DOIUrl":"10.1093/jac/dkag307","url":null,"abstract":"<p><strong>Background: </strong>Haemophilus influenzae resistance to β-lactams is mediated by β-lactamase and amino acid alterations in penicillin-binding protein 3 encoded by ftsI gene, which shows incomplete phenotype-genotype concordance.</p><p><strong>Objectives: </strong>To develop and evaluate a genomic classification framework to predict clinically relevant β-lactam resistance categories.</p><p><strong>Methods: </strong>We analysed 5288 H. influenzae isolates collected in eight European countries and Canada. Among these, 4833 isolates had phenotypic β-lactam susceptibility that were classified into three categories: susceptible to amoxicillin (AMX), resistant to AMX but susceptible to cefotaxime and resistant to both. A 621 bp DNA fragments of the whole ftsI gene (between codons 326 and 532) were analysed to construct category-specific k-mer vocabulary and an allele classifier using Python scripts. Performance was assessed using independent allele validation and agreement with phenotypic classification was evaluated using Cohen's κ coefficient. An additional 455 isolates lacked phenotypic data and were used for external genomic application.</p><p><strong>Results: </strong>Forty-seven frequent ftsI alleles and 34 additional alleles were used for the implementation and the refinement of the vocabulary. Subsequently, 23 other alleles were used for independent allele validation and resulted in correctly predicted resistance categories for 21 alleles (accuracy 91.3%). Agreement with phenotypic classification was high (Cohen's κ 0.853; weighted κ 0.880). Application of the classifier to 455 UK isolates predicted resistance distributions consistent with those observed in phenotypically characterized datasets.</p><p><strong>Conclusions: </strong>A recurrence-filtered k-mer-based vocabulary provides a promising standardized genomic framework that complements phenotypic AST, particularly when phenotypic testing is unavailable, incomplete or heterogeneous.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":"81 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148982846","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":"BV100 (rifabutin IV) drug interaction studies in healthy subjects with index CYP450 3A probes midazolam and itraconazole.","authors":"Pierre Delique, Christian Kemmer, Lisa Husband, Géza Lakner, Jürgen Jäger, Françoise Jung, Andrew F Shorr, Glenn E Dale","doi":"10.1093/jac/dkag317","DOIUrl":"10.1093/jac/dkag317","url":null,"abstract":"<p><strong>Background: </strong>BV100 is a novel intravenous (IV) formulation of rifabutin under development for the treatment of serious Acinetobacter baumannii infections. The primary objectives of these studies were to assess potential pharmacokinetic interactions between BV100 and two index cytochrome P450 3A enzymes (CYP3A) probes, midazolam (substrate) and itraconazole (inhibitor), and to evaluate BV100's safety profile.</p><p><strong>Methods: </strong>Two open-label Phase 1 studies were conducted in healthy participants. Study 1 evaluated the impact of multiple IV doses of BV100 (300 mg) on the pharmacokinetics of a single oral dose of midazolam (5 mg). Study 2 assessed the impact of repeated oral doses of itraconazole (200 mg) on the pharmacokinetics of a single IV dose of BV100 (300 mg). Pharmacokinetic parameters [maximum plasma concentration (Cmax), area under the plasma concentration-time curve from zero to 24 hours (AUC0-24), area under the plasma concentration-time curve from zero to infinity (AUC0-∞)] were analysed using geometric means and 90% confidence intervals (CI). Drug-drug interactions (DDIs) were defined as a 90% CI outside the equivalence range of 80%-125%.</p><p><strong>Results: </strong>Both studies demonstrated DDIs. BV100 increased midazolam metabolism, with Cmax and AUC test/reference ratios of 77% and 53%, respectively. The decreased midazolam AUC (47%) indicated BV100 is a mild/weak CYP3A inducer by EMA/FDA criteria. Itraconazole decreased BV100 metabolism, resulting in increased BV100 exposure (Cmax 1.1-fold; AUC 1.3-1.7-fold), consistent with mild inhibition. BV100 was considered generally safe and well tolerated in both studies, with no serious adverse events reported.</p><p><strong>Conclusion: </strong>BV100 is a mild/weak CYP3A enzyme inducer and a mild substrate for CYP3A inhibitors. However, co-administration with strong CYP3A inhibitors resulted in a disproportionate increase in exposure to the active metabolite 25-O-desacetyl rifabutin, leading to an ∼2-fold increase in total active-moiety exposure. Clinical monitoring is advised when BV100 is co-administered with a strong CYP3A inhibitor. BV100 was safe and well tolerated.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":"81 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13574503/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148968829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comment on: 'Clinical outcomes of beta lactam monotherapy versus beta-lactam plus azithromycin in hospitalized patients with community-acquired pneumoniae'.","authors":"Evangelos J Giamarellos-Bourboulis, Michael S Niederman","doi":"10.1093/jac/dkag302","DOIUrl":"https://doi.org/10.1093/jac/dkag302","url":null,"abstract":"","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":"81 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148906286","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":"Factors influencing antibiotic use in confirmed viral respiratory tract infections.","authors":"Siti Mardhiah Muhamad Fauzii, Azonim Egwu, Maebh Kelleher, Brian D Kent, Rory Nee, Aileen Conway, Jonathan McGrath, Colm Bergin, Liam Townsend","doi":"10.1093/jac/dkag321","DOIUrl":"10.1093/jac/dkag321","url":null,"abstract":"<p><strong>Background: </strong>The use of antibiotic therapy in confirmed viral respiratory tract infections is controversial, with discordance amongst guidelines.</p><p><strong>Objectives: </strong>We evaluated antibiotic usage in patients admitted with confirmed influenza A, respiratory syncytial virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, as well as factors associated with their initiation and duration.</p><p><strong>Methods: </strong>This was a prospective observational cohort study of patients admitted to a tertiary centre with PCR-confirmed viral respiratory tract infection. Patient characteristics, antibiotic use, choice, route and duration, as well as patient outcomes were measured. Clinical and microbiological factors related to the admission were recorded. Multivariate regression analyses were used to identify factors associated with antibiotic initiation and duration.</p><p><strong>Results: </strong>There were 241 admissions with confirmed viral respiratory tract infections over the 2025/26 winter period. Antibiotic therapy was commenced in 208 (86%) cases, with a median 7 days of therapy given. Additional cultures were taken from 159, with positive bacterial cultures in 35 (35/159, 22%). A requirement for supplemental oxygen (OR 4.61, P = 0.02) and increased C-reactive protein at admission (OR 1.03, P < 0.001) were associated with increased likelihood to commence antibiotics, while ongoing supplemental oxygen requirement (β coefficient 0.41, P = 0.005) was associated with increased duration of antibiotic therapy. Antibiotic duration was not influenced by bacterial culture results.</p><p><strong>Conclusions: </strong>We demonstrate high rates of antibiotic usage in patients admitted with confirmed viral respiratory tract infection, and identify opportunities for improved antimicrobial stewardship.</p>","PeriodicalId":14969,"journal":{"name":"Journal of Antimicrobial Chemotherapy","volume":"81 10","pages":""},"PeriodicalIF":4.1,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13595220/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149017008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}