Detection of Klebsiella pneumoniae carbapenemases and metallo-β-lactamases among Klebsiella pneumoniae isolates from hospitalized patients at Menoufia University Hospitals, Egypt

Objectives The aim of the study was to determine the incidence of carbapenem resistance among Klebsiella pneumoniae isolates in Menoufia University Hospitals and detect the production of Klebsiella pneumoniae carbapenemases (KPCs) and metallo-b-lactamases (MbLs) using phenotypic and molecular methods and correlate their presence with in-vitro susceptibility to carbapenems. Background Carbapenem-hydrolyzing b-lactamases are the most powerful b-lactamases. KPCs and MbLs are able to hydrolyze carbapenems, which cause resistance to multiple classes of antibiotics. Materials and methods The study was conducted on 128 K. pneumoniae isolates. Carbapenemase production was detected by antibiotic susceptibility testing against imipenem (IPM), meropenem, and ertapenem and by IPM minimal inhibitory concentration assays. Results were confirmed by the modified Hodge test, the phenylboronic acid combined disk (PBA-CD) test, and the IPM/EDTA combined disk (IPM/EDTA-CD) test. Detection of carbapenemase genes (blaKPC, blaVIM, and blaIMP) was performed by multiplex PCR. Results Eighty K. pneumoniae isolates were reported as IPM resistant. Class A carbapenemases (KPCs) were detected in 35% of IPM-resistant K. pneumoniae by the PBA-CD test. Class B carbapenemases (MbLs) were detected in 48.8% of IPM-resistant K. pneumoniae by the IPM/EDTA-CD test. Age, long hospital stay, invasive procedures, and history of drug intake (carbapenem) were high-risk factors for IPM-resistant K. pneumoniae. Among IPM-resistant isolates, 17.5% were positive for the blaKPC gene and 43.75% were positive for the blaVIM and blaIMP genes. In relation to PCR, the sensitivity and specificity of the PBA-CD test were 85.7 and 75.8%, respectively, whereas for the IPM/EDTA-CD test sensitivity and specificity were 94.3 and 86.7%, respectively. Conclusion Laboratory identification of carbapenemase-harboring clinical isolates is necessary for implementing contact precautions, for outbreak detection, and for proper choice of effective therapy. Phenotypic and molecular-based techniques identify carbapenemase producers with variable efficiencies.