Defining antimicrobial susceptibility testing methods and breakpoints among Achromobacter species

作者：Harley Harris, Haley Stambaugh, Emily Jacobs, Amira A. Bhalodi, Sukantha Chandrasekaran, Nicolynn C. Cole, Jennifer Lu, Tsigereda Tekle, Romney M. Humphries, Patricia J. Simner · 发表于：Journal of Clinical Microbiology · 年份：2025 · DOI：10.1128/jcm.00264-25 · 被引用次数：9 · 研究领域：Infections and bacterial resistance、Antibiotic Resistance in Bacteria、Plant Pathogenic Bacteria Studies

ABSTRACT Achromobacter species can cause opportunistic infections which are difficult to treat due to a variety of antimicrobial resistance (AMR) mechanisms. As such, antimicrobial susceptibility testing (AST) is a cornerstone to successful treatment for these organisms. Currently, there are no specific Clinical and Laboratory Standards Institute (CLSI) AST guidelines for Achromobacter species. The purpose of this study was to (i) establish tentative CLSI M45 MIC and disk diffusion (DD) breakpoints (BPs), (ii) evaluate the modified carbapenem inactivation method (mCIM), and (iii) understand the mechanisms mediating AMR among Achromobacter species. Contemporary MIC data from multiple sources were collated to define the tentative epidemiological cutoff values (tECVs), and the MIC distributions were used to inform the establishment of MIC BPs for various agents. A disk-to-MIC correlate study with 91 isolates from across the United States was completed by testing reference broth microdilution and DD from the same inoculum and applying the dBETS software to establish DD BPs. Lastly, the mCIM and whole-genome sequencing (WGS) were pursued. The tECVs for piperacillin-tazobactam, imipenem, and meropenem were 1, 2, and 0.5 µg/mL, respectively. Disk correlates met CLSI M23 acceptance criteria with a few exceptions related to a small number of isolates, resulting in high minor errors. WGS revealed that 82 (90.1%) isolates harbored a bla OXA variant with bla OXA-114 predominating (90.2%)...