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<p>Carbapenem resistance in <i>Klebsiella pneumoniae</i> is primarily mediated by carbapenemase production. This study aimed to identify carbapenemase genes in carbapenem-resistant <i>K. pneumoniae</i> isolates using multiplex polymerase chain reaction (PCR) and to evaluate the performance of the combination disk assay (CDA) as a phenotypic detection method. A total of 123 carbapenem-resistant <i>K. pneumoniae</i> isolates were analyzed. Colistin and meropenem susceptibility were determined by broth microdilution, while ceftazidime-avibactam susceptibility was assessed using disk diffusion. Five common carbapenemase genes (<i>blaOXA-48</i>, <i>blaNDM</i>, <i>blaKPC</i>, <i>blaIMP</i>, <i>blaVIM</i>) were detected by multiplex PCR. CDA was performed using meropenem and temocillin disks in combination with specific inhibitors (EDTA, boronic acid, cloxacillin). Colistin (59.3%) and ceftazidime-avibactam (58.5%) showed the highest susceptibility rates. PCR identified <i>blaOXA-48</i> in 53.6%, <i>blaKPC</i> in 45.5%, and <i>blaNDM</i> in 32.5% of isolates. CDA detected MBL, KPC, and OXA-48 enzymes in 44.7%, 44.7%, and 10.6% of isolates, respectively, and failed to detect OXA-48 in the presence of NDM. Compared with PCR, CDA showed excellent agreement for KPC detection (sensitivity 100%, specificity 100%; κ = 0.984), moderate agreement for MBL (sensitivity 95%, specificity 76.1%; κ = 0.679), and poor agreement for OXA-48 (sensitivity 19.7%, specificity 100%; κ = 0.185). CDA may be used as an initial phenotypic screening tool for the detection of KPC-producing isolates; however, its limited ability to detect OXA-48 and carbapenemase co-production restricts its reliability for broader clinical interpretation. Therefore, PCR-based methods remain essential for accurate confirmation and surveillance.</p>

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Phenotypic and genotypic investigation of carbapenemases in carbapenem-resistant Klebsiella pneumoniae isolates

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年3月7日

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  • Serpil Genç,
  • Ayten Nur Uzun,
  • Hilal Tanriverdi̇

摘要

Carbapenem resistance in Klebsiella pneumoniae is primarily mediated by carbapenemase production. This study aimed to identify carbapenemase genes in carbapenem-resistant K. pneumoniae isolates using multiplex polymerase chain reaction (PCR) and to evaluate the performance of the combination disk assay (CDA) as a phenotypic detection method. A total of 123 carbapenem-resistant K. pneumoniae isolates were analyzed. Colistin and meropenem susceptibility were determined by broth microdilution, while ceftazidime-avibactam susceptibility was assessed using disk diffusion. Five common carbapenemase genes (blaOXA-48, blaNDM, blaKPC, blaIMP, blaVIM) were detected by multiplex PCR. CDA was performed using meropenem and temocillin disks in combination with specific inhibitors (EDTA, boronic acid, cloxacillin). Colistin (59.3%) and ceftazidime-avibactam (58.5%) showed the highest susceptibility rates. PCR identified blaOXA-48 in 53.6%, blaKPC in 45.5%, and blaNDM in 32.5% of isolates. CDA detected MBL, KPC, and OXA-48 enzymes in 44.7%, 44.7%, and 10.6% of isolates, respectively, and failed to detect OXA-48 in the presence of NDM. Compared with PCR, CDA showed excellent agreement for KPC detection (sensitivity 100%, specificity 100%; κ = 0.984), moderate agreement for MBL (sensitivity 95%, specificity 76.1%; κ = 0.679), and poor agreement for OXA-48 (sensitivity 19.7%, specificity 100%; κ = 0.185). CDA may be used as an initial phenotypic screening tool for the detection of KPC-producing isolates; however, its limited ability to detect OXA-48 and carbapenemase co-production restricts its reliability for broader clinical interpretation. Therefore, PCR-based methods remain essential for accurate confirmation and surveillance.