Prevalence and clonal relatedness of NDM and OXA-48-producing Klebsiella pneumoniae in a tertiary care hospital in South India

BACKGROUND: Carbapenems are used for the treatment of serious infections caused by multidrug-resistant Klebsiella pneumoniae. Resistance to carbapenems in K. pneumoniae is mainly due to metallo-beta-lactamases (NDM, IMP, and VIM) and class D oxacillinase (OXA-48-like). AIM AND OBJECTIVE: This study was undertaken to detect the genes encoding for carbapenemase in K. pneumoniae and to determine the clonal relatedness of selected isolates of K. pneumoniae producing NDM and OXA-48 by pulsed-field gel electrophoresis method (PFGE). MATERIALS AND METHODS: The isolates were collected over a period of 1 year. A total of 370 clinically significant, nonduplicate isolates of K. pneumoniae were included in this study. Phenotypic tests for the detection of carbapenemases were performed for all the isolates. Polymerase chain reaction (PCR) was carried out for the detection of carbapenemase genes such as blaKPC, blaIMP, blaVIM, blaNDM, and blaOXA-48. PFGE was performed, and the PFGE profiles were analyzed and compared using BioNumerics version 7.6. RESULTS: Of the 370 isolates of K. pneumoniae, carbapenemase genes were detected in 13.78% (51/370). blaOXA-48 was the prevalent gene detected followed by blaNDM and blaKPC. Thirty strains of K. pneumoniae selected by PFGE analysis were divided into five clusters (A, B, C, D, and E). Cluster C was the major type detected carrying blaNDM and blaOXA-48 genes. CONCLUSION: blaOXA-48 was the most prevalent gene detected in this study. PCR is useful in detecting carbapenemase genes, especially blaNDM, which may show false susceptibility to carbapenems. There was no direct correlation detected between PFGE profiles and antibiotic susceptibility pattern. PFGE has revealed the genomic diversity among isolates, thereby suggesting heterogeneity in strain circulation within intensive care unit and wards of the hospital. Monitoring and molecular typing is essential to curtail the spread of multidrug-resistant strains and control the outbreaks of infection.