[Distribution of phylogenetic groups and virulence factors in CTX-M-15 β-lactamase-producing uropathogenic Escherichia coli strains isolated from patients in the community of Mérida, Venezuela]

Abstract

In this study, the distribution of phylogenetic groups and the genetic detection of virulence factors in CTX-M-15 β-lactamase-producing uropathogenic Escherichia coli (UPEC) strains were analyzed. Twenty eight strains were isolated between January 2009 and July 2011 from patients with urinary tract infection (UTI) who attended the Public Health Laboratory at Mérida, Venezuela. Determination of phylogenetic groups and detection of six virulence genes, fimH, fyuA, kpsMTII, usp, PAI and papAH, were performed by PCR amplification. Fifteen of the 28 isolates were mainly located in the phylogenetic group A, followed by B2 (12/28) and D (1/28). No direct relationship between the severity or recurrence of UTI and the distribution of phylogroups was observed. All studied virulence factors were found in group B2 strains with the highest frequency. The prevalent virulence profile included the combination of three main genes: fimH, kpsMTII and fyuA and, to a lesser extent, the presence of other determinants such as usp, PAI and/or papAH. These results indicate that virulent UPEC incorporated three important properties: adhesion, iron uptake and evasion of phagocytosis, which favored the production of recurrent UTI. This is the first report describing the association of phylogenetic groups with the potential virulence of CTX-M-15 β-lactamase producing UPEC strains in Venezuela.

Keywords: Beta-lactamasa CTX-M-15; CTX-M-15 beta-lactamase; Escherichia coli uropatógena; Grupos filogenéticos; Phylogenetic groups; Uropathogenic Escherichia coli; Virulence; Virulencia.