Emma Graffice, Derek B Moates, Sixto M Leal, Megan Amerson-Brown, Juan J Calix
{"title":"Epidemiological, phylogenetic, and resistance heterogeneity among Acinetobacter baumannii in a large U.S. Deep South healthcare system","authors":"Emma Graffice, Derek B Moates, Sixto M Leal, Megan Amerson-Brown, Juan J Calix","doi":"10.1093/ofid/ofae458","DOIUrl":null,"url":null,"abstract":"Background Acinetobacter baumannii (Ab) disease in the U.S. is commonly attributed to outbreaks of one or two monophyletic carbapenem resistance (CR) Ab lineages that vary by region. However, there is limited knowledge regarding CRAb epidemiology and population structures in the U.S. Deep South, and few studies compare contemporary CR and carbapenem susceptible (Cs) Ab, despite relative prevalence of the latter. Methods We performed a multiyear analysis of 2462 Ab cases in a large healthcare system in Birmingham, AL, and 89 post-2021 Ab isolates were sequenced and phenotyped by antibiotic susceptibility tests (AST). Results: While the cumulative CR rate was 17.7% in our cohort, rates regularly increased in winter months as result of seasonal changes in case incidence of CsAb, specifically. Genotyped CRAb belonged to clonal group (CG) 1, CG2, CG108, CG250, or CG499, with local clones of CG108, CG250 and CG499 persisting over multiple months. There was no clonal expansion of any CsAb lineage. Among CRAb isolates, levels of β-lactam antibiotic resistance and the repertoire of related genetic resistance determinants, which included the novel CR-conferring FtsI A515V polymorphism, differed according to CG. CG108 and CG499 isolates displayed specific heteroresistance to sulbactam and trimethoprim/sulfamethoxazole, respectively, which resulted in discrepant susceptibility results in microbroth versus agar-based AST modalities. Conclusions We report an unusually high degree of CRAb phylogenetic diversity principally driven by emergent U.S. lineages harboring novel resistance elements that must be incorporated into diagnostic, surveillance, and pre-clinical research efforts.","PeriodicalId":19517,"journal":{"name":"Open Forum Infectious Diseases","volume":null,"pages":null},"PeriodicalIF":3.8000,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Open Forum Infectious Diseases","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1093/ofid/ofae458","RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"IMMUNOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Background Acinetobacter baumannii (Ab) disease in the U.S. is commonly attributed to outbreaks of one or two monophyletic carbapenem resistance (CR) Ab lineages that vary by region. However, there is limited knowledge regarding CRAb epidemiology and population structures in the U.S. Deep South, and few studies compare contemporary CR and carbapenem susceptible (Cs) Ab, despite relative prevalence of the latter. Methods We performed a multiyear analysis of 2462 Ab cases in a large healthcare system in Birmingham, AL, and 89 post-2021 Ab isolates were sequenced and phenotyped by antibiotic susceptibility tests (AST). Results: While the cumulative CR rate was 17.7% in our cohort, rates regularly increased in winter months as result of seasonal changes in case incidence of CsAb, specifically. Genotyped CRAb belonged to clonal group (CG) 1, CG2, CG108, CG250, or CG499, with local clones of CG108, CG250 and CG499 persisting over multiple months. There was no clonal expansion of any CsAb lineage. Among CRAb isolates, levels of β-lactam antibiotic resistance and the repertoire of related genetic resistance determinants, which included the novel CR-conferring FtsI A515V polymorphism, differed according to CG. CG108 and CG499 isolates displayed specific heteroresistance to sulbactam and trimethoprim/sulfamethoxazole, respectively, which resulted in discrepant susceptibility results in microbroth versus agar-based AST modalities. Conclusions We report an unusually high degree of CRAb phylogenetic diversity principally driven by emergent U.S. lineages harboring novel resistance elements that must be incorporated into diagnostic, surveillance, and pre-clinical research efforts.
期刊介绍:
Open Forum Infectious Diseases provides a global forum for the publication of clinical, translational, and basic research findings in a fully open access, online journal environment. The journal reflects the broad diversity of the field of infectious diseases, and focuses on the intersection of biomedical science and clinical practice, with a particular emphasis on knowledge that holds the potential to improve patient care in populations around the world. Fully peer-reviewed, OFID supports the international community of infectious diseases experts by providing a venue for articles that further the understanding of all aspects of infectious diseases.