Evaluation of clonality in enterococci isolated in Brazil carrying Tn1546-like elements associated with vanA plasmids

Abstract

Fifty-one vancomycin-resistant enterococci samples isolated from different geographic regions in Brazil were studied. All the isolates harboured the vanA gene as demonstrated by PCR analysis, and in a majority of strains the gene was associated with a transferable plasmid of 70 kb. A single variant of the prototype Tn1546 associated with common transferable vanA-containing plasmids has spread among the enterococcal strains circulating in Brazil. The VanA element integrity in these enterococci strains and the different pulsed-field gel electrophoresis patterns suggest horizontal transmission of the vancomycin resistance transposon in Brazilian strains.

Genetic Rearrangements of Tn 1546 -Like Elements in Vancomycin-Resistant Enterococcus faecium Isolates Collected from Hospitalized Patients over a Seven-Year Period

“…The genetic diversity in Tn1546-like elements, including the integration of IS elements IS1216V, IS1251, IS1476, and IS1542, has been documented previously (16,17 (8). Tn1546-like elements may move more into previously susceptible enterococcal strains via plasmids or transposons (1,4), particularly when VRE become endemic in a hospital (5,11). The reason for the rapid spread of VRE can possibly be explained by such a mobility of Tn1546-like elements that have adapted to adverse environmental conditions (6).…”

“…The heterogeneity of the Tn1546-like element results from point mutations, deletions, and the integration of insertion sequence (IS) elements (16,17); and among these variations, the presence of IS elements accounts for much of the heterogeneity (3). Such a rearrangement has been shown to play a key role in the evolution of the vanA gene cluster and may modify its transferability (7,8,11). In the present study, we characterized the consequence of Tn1546 in vanA-containing Enterococcus faecium isolates collected from patients over time passed to obtain an understanding of the hospital dissemination of VRE over time.…”

“…Generally, the main mechanism for the dissemination of the van gene in enterococci could be the clonal dissemination of VRE, but the horizontal transfer of a resistance gene cluster has also been suggested to be a significant mechanism (6,10,11). Pulsed-field gel electrophoresis (PFGE) has been widely employed to obtain an understanding of the clonal dissemination of VRE, and structural analyses of the Tn1546-like element have recently been introduced to gain an understanding of the horizontal transfer of the resistance gene cluster.…”

Diversity of Tn 1546 and Its Role in the Dissemination of Vancomycin-Resistant Enterococci in Portugal

“…The genes forming the VanA operon are part of a 10.8-kb Tn3 derivative designated Tn1546, often located on conjugative plasmids (8,12,34,41,42). Variants of this transposon containing mutations, deletions, and different insertion sequences have been reported, and a presumptive association between specific Tn1546 types and geographical areas and/or environmental sources has been suggested (4,15,19,32,38,44,45).…”

Virulence factors in vancomycin-resistant and vancomycin - susceptible Enterococcus faecalis from Brazil

“…However, no other VanD strains have been reported in Brazil. On the other hand, a predominant clone of vancomycin-resistant E. faecalis (VREFS) VanA has recently been disseminating throughout hospitals in Sao Paulo and other cities (8,18,19). It was of interest to identify virulence factors and antibiotic resistance profiles among isolates of the disseminating clone and compare them with subsets of vancomycin-sensitive E. faecalis (VSEFS) from several sources in Brazil.…”