Phenotypic and genotypic investigation of carbapenemases in carbapenem-resistant Klebsiella pneumoniae isolates
FOLIA MICROBIOLOGICA, vol.71, pp.1-8, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 71
- Publication Date: 2026
- Doi Number: 10.1007/s12223-026-01443-z
- Journal Name: FOLIA MICROBIOLOGICA
- Journal Indexes: Scopus, Science Citation Index Expanded (SCI-EXPANDED), BIOSIS, Chemical Abstracts Core
- Page Numbers: pp.1-8
- Kütahya Health Sciences University Affiliated: Yes
Abstract
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.