Alliance of Efflux Pumps with β-Lactamases in Multidrug-Resistant Klebsiella pneumoniae Isolates.

Navdezda Maurya,Rushikesh Tambat,Manoj Jangra,Hemraj Nandanwar

doi:10.1089/mdr.2018.0414

Navdezda Maurya, Rushikesh Tambat + Show 2 more

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https://doi.org/10.1089/mdr.2018.0414

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Abstract

Nosocomial infections caused by Klebsiella pneumoniae are primarily characterized by a high prevalence of extended-spectrum β-lactamases (ESBL's) and a soaring pace of carbapenemase dissemination. Availability of limited antimicrobial agents as a therapeutic option for multidrug-resistant bacteria raises an alarming concern. This study aimed at the molecular characterization of multidrug-resistant K. pneumoniae clinical isolates and studied the role of efflux pumps in β-lactam resistance. Thirty-three isolates confirmed as ESBL-positive K. pneumoniae that harbored resistance genes to major classes of antibiotics. The results showed that CTX-M15 was the preeminent β-lactamase along with carbapenemases in ESBL-positive isolates. However, the efficacy of different antibiotics varied in the presence of lactamase inhibitors and efflux pump inhibitors (EPIs). Those showing increased efficacy of antibiotics with EPI were further explored for the expression of efflux pump genes and expressed a significantly different level of efflux pumps. We found that an isolate had higher expression of kpnF (SMR family) and kdeA (MATE family) pump genes relative to RND family pump genes. No mutations were observed in the genes for porins. Together, the findings suggest that β-lactamases are not the only single factor responsible for providing resistance against the existing β-lactam drugs. Resistance may increase many folds by simultaneous expression of RND family (the most prominent family in Gram-negative bacteria) and other efflux pump family.

Highlights

Klebsiella pneumoniae imparts a significant burden on the health care system as a leading causative agent of nosocomial infections with multidrug resistance/extreme drug resistance (MDR/XDR) phenotype.[1]
Extended-spectrum b-lactamase (ESBL)-positive nosocomial isolates from ICU patients were collected during the year 2013–2014 from Government Medical College and Hospital (GMCH), Chandigarh, India. 16S rRNA gene sequences for all clinical isolates were amplified using primers 27F (5¢-AGAGTTTGATCCTGGCTCAG-3¢) and 1492R (5¢-TACGGCTACCTTGTTACGACTT-3¢)[14] by conventional PCR and similarities were achieved using EzTaxon server.* The taxonomically confirmed K. pneumoniae isolates were further taken for studies
Genomic and plasmid DNA were isolated from the strains to check the presence or absence of b-lactamases by PCR

Summary

Introduction

Klebsiella pneumoniae imparts a significant burden on the health care system as a leading causative agent of nosocomial infections with multidrug resistance/extreme drug resistance (MDR/XDR) phenotype.[1] The reduced efficacy of available drugs at a much faster pace is agitating the situation more than the nonavailability of new drugs.[2] Among the few therapeutic options used as a last resort, one is carbapenems, from many b-lactam antibiotics approved. Primary mechanisms of resistance against b-lactams are widely reported as enzymatic deactivation of antibiotics and reducing membrane permeability.[5] Several reports provide evidence for the reduced uptake of antibiotics due to the permeability barriers caused by mutations or loss of porins.[6]

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