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

Abstract

Background: In Argentina, there has been an abrupt increase in KPC-2-producing Klebsiella pneumoniae (K. pneumoniae). Tucumán is a multi-border area, so the rapid dissemination of carbapenem-resistant K. pneumoniae is a clinically relevant problem for the region.

Objectives: This study aimed to investigate the epidemiological and molecular patterns of KPC-producing K. pneumoniae clinical isolates collected from different hospitals in Tucumán.

Methods: Carbapenem-resistant K. pneumoniae strains were sequentially and uniquely collected during two time periods. Antibiotic susceptibility was determined by the automated Vitex 2® system and using the standard agar dilution test. Multilocus sequence typing and pulsed-field electrophoresis were used for epidemiological analysis. The genetic structures around bla_KPC and the encoding genes of extended-spectrum β-lactamases were detected by polymerase chain reaction and sequencing. Plasmids were analysed by conjugation and using the plasmid relaxase gene-typing method.

Results: All 37 isolates were multidrug resistant, and thebla_KPC-2 gene was confirmed in all of them. In 17 isolates (45.9%), the bla_CTX-M-2 gene was also amplified, as well as bla_SHV-2 in five isolates (13.5%) and bla_CTX-M-2/bla_SHV-2 in four isolates (10.8%). The molecular epidemiology of the bla_KPC-2 gene has resulted in it being associated with an IncL/M transferable plasmid disseminating in various sequence types (STs) (ST17, ST556, ST342, ST147, ST461, ST65, ST15 and ST70), and in a new genetic environment with a 764-bp deletion in the ISKpn7-bla_KPC region.

Conclusions: These findings contribute to the understanding of the great diversity of the bla_KPC-2-carrying genetic platforms.

Keywords: Genetic environment; KPC β-lactamases; Molecular epidemiology.