Clonal diversity of multidrug-resistant Klebsiella pneumoniae from ICU patients in central Türkiye.

Abstract

The increasing prevalence of multidrug-resistant (MDR) Klebsiella pneumoniae, particularly carbapenem-resistant strains, represents a major clinical challenge worldwide. Data on the molecular characteristics of MDR K. pneumoniae in central Türkiye remain limited. This study aimed to characterize the antimicrobial resistance profiles and molecular features of MDR-K. pneumoniae isolates recovered from hospitalized patients in a tertiary care hospital in central Türkiye.A total of 1,560 clinical specimens collected from intensive care unit (ICU) patients between November 2024 and June 2025 were analyzed. Thirty-three non-duplicate MDR-K. pneumoniae isolates obtained from 26 patients were included. Identification and antimicrobial susceptibility testing were performed using the VITEK®2 system. ESBL genes (blaTEM, blaSHV, blaCTX-M groups), carbapenemase genes (blaKPC, blaOXA-48, blaNDM-1), virulence-associated genes (iucA, rmpA2), and efflux pump genes (acrAB, tolC) were investigated by PCR. Clonal relatedness was assessed by pulsed-field gel electrophoresis (PFGE).All isolates were resistant to multiple β-lactams and ciprofloxacin. Resistance to meropenem and amikacin was observed in 97.0% of isolates, while 94.0% were resistant to gentamicin. Colistin and ceftazidime-avibactam resistance rates were 27.3 and 18.2%, respectively. The most prevalent genes were blaSHV (90.9%), blaCTX-M-1 (81.8%), and blaOXA-48 (66.7%), whereas blaTEM, blaKPC and blaNDM-1 were detected in 36.4, 21.2 and 3.0% of isolates, respectively. None of the isolates carried iucA or rmpA2. PFGE revealed substantial genetic diversity with multiple pulsotypes and no dominant epidemic clone.These findings demonstrate the dissemination of genetically diverse MDR K. pneumoniae lineages carrying ESBL and OXA-48 carbapenemase genes in an ICU setting in central Türkiye. Despite occasional hypermucoviscosity, no molecular evidence of hypervirulence was detected, highlighting the need for continuous molecular surveillance and effective infection-control measures.