Detection of QNRB and AAC(6')-IB-CR in the clinical isolates of non-extended spectrum beta lactamase producing k.pneumoniae in Hospital Tengku Ampuan Afzan, Kuantan, Pahang

Abstract

Fluoroquinolones (FQ) are a group of broad-spectrum antibiotics, used for treating a variety of infectious diseases but growing resistance to FQ among Enterobacteriaceae is a serious clinical obstacle faced by the clinicians in successfully treating infections caused by them. Although plasmid-mediated quinolone resistance (PMQR) genes confer a low level of resistance, organisms harboring them pose a real threat as they can go undetected by common phenotypic testing for antimicrobial resistance used in the diagnostic laboratory. Moreover, they can facilitate clinical resistance by inducing chromosomal mutation for antibacterial resistance. They can spread rapidly to other species via horizontal gene transfer. In an attempt to determine the presence and frequency of plasmid meditated quinolone resistance genes in terms of qnrB and aac(6?)-Ib-cr in the clinical isolates of non-extended spectrum beta lactamase (ESBL) producing K. pneumoniae, we collected 40 isolates of non-ESBL producing K. pneumoniae from various clinical specimens from the pathology laboratory of Hospital Tengku Ampuan Afzan, Kuantan, Pahang. After establishing their identification by standard biochemical tests, the plasmid DNA was extracted from the isolates using a commercial plasmid DNA extraction kit. Conventional PCR amplifications were performed to evaluate the presence and frequency of PMQR genes particularly qnrB and aac(6?)-Ib-cr among the collected isolates. Kirby-Bauer antimicrobial susceptibility test (AST) was done for all collected isolates to determine their susceptibility or resistance status to commonly used fluoroquinolones. The PCR results revealed that only 5% of the isolates harbored the qnrB gene, while none were positive for the aac(6?)-Ib-cr gene. AST showed only 2 isolates were resistant, 3 were intermediately susceptible and all the rest 33 isolates were susceptible to the tested fluoroquinolones. This study detected the presence of qnrB among clinical isolates of K. pneumoniae in Kuantan, which warrants for broader surveillance to know and follow its prevalence in order to take intervention measures to prevent its dissemination among other species.