Novel patterns in the molecular epidemiology of KPC-producing Klebsiella pneumoniae in Tucuman, Argentina.

Abstract

BACKGROUND\nIn Argentina, there was an abrupt increase of KPC-2-producing Klebsiella pneumoniae; Tucuman is a multi-border area so the rapid dissemination of carbapenem-resistant K. pneumoniae constituted a clinical relevant problem of our region.\n\n\nOBJECTIVES\nIn this study, we aimed to investigate the epidemiological and molecular patterns of KPC-producingK. pneumoniae clinical isolates, collected from different hospitals in Tucumán.\n\n\nMETHODS\nCarbapenem- resistant K. pneumoniae strains were sequential and nonduplicated collected. in two periods of time. Antibiotic susceptibility was determined by the automated Vitex 2® system and using standard agar dilution test. Multilocus sequence typing (MLST) and pulsed-field electrophoresis (PFGE) were used for epidemiological análisis. The genetic structures around blaKPC and the encoding genes of extended-spectrum β-lactamases were detected by PCR and sequencing. Plasmids were analysed by conjugation and using the plasmid relaxase gene-typing method.\n\n\nRESULTS\nAll 37 isolates were multidrug resistant, theblaKPC-2 gene was confirmed in all of them. In 17 isolates (45.9%) the blaCTX-M-2 gene was also amplified, as well as blaSHV-2 in 5 isolates (13.5%) and blaCTX-M-2 / blaSHV-2 in 4 isolates (10.8%). The molecular epidemiology of blaKPC-2 gene, resulted associated with an IncL/M transferable plasmid disseminating in various STs (ST17, ST556, ST342, ST147, ST461, ST65, ST15 and ST70), and in a new genetic environment with a 764-bp deletion in the ISKpn7- blaKPC region.\n\n\nCONCLUSIONS\nThese findings contribute to the understanding of the high diversity of blaKPC-2-carrying genetic platforms.