Identificação e caracterização de genes de resistência a antimicrobianos e fatores de virulência em isolados clínicos multirresistentes de Enterococcus faecalis e Enterococcus faecium

Abstract

In this study, we evaluated the antimicrobial susceptibility, the presence of gene-encoding virulence factors and CRISPR systems, as well as the ability to produce lytic enzymes among clinical E. faecalis and E. faecium isolates (n=44). All enterococci isolates showed phenotypes of multi-drug resistance. Half of the E. faecalis isolates exhibited high-level gentamicin resistance phenotype, several of them harboring the aac(6')Ie-aph(2″)Ia gene. The gene vanA was the most frequent among vancomycin-resistant E. faecium. High prevalence of the virulence genes esp and efaA were observed; hyl gene was more associated with E. faecium, while ace and efaA genes were more frequently detected in E. faecalis. Caseinase activity was frequently detected among the isolates. Gelatinase and DNAse activities predominated among E. faecalis, while hemolytic capability was frequent among E. faecium isolates. Twenty-nine isolates showed at least one CRISPR system investigated. Several E. faecalis isolates harbored the aac(6’)-Ie-aph(2’’)-Ia gene and a CRISPR loci. CRISPR loci were positively correlated to efaA and gelE genes, and gelatinase and DNAse activities, while CRISPR loci absence was related to hyl gene presence. These results show that hospital- adapted strains of E. faecalis and E. faecium harboring virulence genes show the concomitant presence of CRISPR loci and antibiotic resistance determinants.