Molecular basis of carbapenem and colistin resistance and <i>phoQ</i> mutation-mediated colistin resistance in <i>Acinetobacter baumannii</i> from Bangladesh

ABSTRACT Carbapenem- and colistin-resistant Acinetobacter baumannii pose a serious global health threat due to limited therapeutic options and rapid dissemination of resistance determinants. This cross-sectional study investigated known carbapenemase and colistin resistance genes among clinical A. baumannii isolates from hospitalized patients in Chattogram, Bangladesh. A total of 325 clinical specimens (urine, wound swab, sputum, blood, and endotracheal aspirate) were processed by standard microbiological methods. Species confirmation was performed by 16S rRNA gene amplification. Antimicrobial susceptibility was determined by the Kirby-Bauer method, and colistin MICs were measured by broth microdilution. Among 239 bacterial isolates, 26 (10.9%) were confirmed as A. baumannii . High resistance rates were observed for ciprofloxacin (65.4%), cefepime (65.4%), meropenem (53.9%), and imipenem (46.2%). Four isolates (15.4%) were…