Characterization of antimicrobial resistance genes in KPC-producing Klebsiella pneumoniae isolated from several hospitals of São Paulo State, Brazil

Abstract

K. pneumoniae producing extended-spectrum b-lactamases (ESBLs) are frequently involved in hospital infections in intensive care unit (ICU), including neonatal ICU. ESBLs are capable of hydrolyzing all penicillins, cephalosporins and aztreonam, and the most prevalent ESBL in Brazil is CTX-M-2. Carbapenems are considered the agents of choice for treatment of infections caused by ESBL-producing microorganisms. However, production of carbapenemases, such as metallo-b-lactamases (IMP, NDM, SPM, etc) and Klebsiella pneumoniae carbapenemase (KPC), which degrade b-lactam antimicrobial agents including carbapenems, complicates treatment of infection caused by K. pneumoniae. IMP-1 and KPC-2 are the most common carbapenemases in Brazil. Moreover, P. aeruginosa and K. pneumoniae producing 16S rRNA methylase, RmtD, which confers high-level resistance to aminoglycosides, which are often used in combination with carbapenems for treatment of severe infections, have been described in Brazil, limiting the therapeutical options.This study aims to characterize resistance genes responsible to the production of b-lactamases , with a focus on estended-spectrum b-lactamases (ESBL), carbapenemases (Klebsiella pneumoniae carbapenemase-KPC and metalo-b-lactamases- MBL), which degrades all b-lactams, including carbapenems, and 16S rRNA methylases, which confers high-level resistance to aminoglycosides, which are often used in combination with carbapenems for treatment of severe infections limiting the therapeutical options. Approximately 100 K. pneumoniae isolates previously confirmed as KPC producers by using antimicrobial susceptibilty tests (disk-difusion and dillution) and PCR using specific primers for blaKPC genes detection, will be subjected to PCR for the detection of the following resistance genes: blaCTX-M, blaSHV, blaGES, blaTEM, blaIMP, blaSPM, blaNDM, armA, rmtA, rmtB rmtC rmtD, etc. PCR amplified products will be purified and submitted to the DNA sequencing. PCR mapping or genomic cloning will be performed as appropriate to define the genetic context of these genes.Identification of resistance mechanisms in multidrug-resistant K. pneumoniae isolates will contribute in the implementation of effective measures in the hospitals to contain the dissemination of these microorganisms. (AU)