Emergence of vanA vancomycin-resistant Enterococcus faecium in a hospital in Porto Alegre, South Brazil.

INTRODUCTION: In Porto Alegre (South Brazil), since the first VRE isolation in 2000 until the middle of the last decade, the epidemiology of enterococcal infections presented the peculiarity that, as opposed to other regions of the country, almost all VRE were E. faecalis. The aim of this study was to investigate the microbiological and epidemiological characteristics of a VRE outbreak that occurred between August 2010 and September 2011 in Porto Alegre, South Brazil. METHODOLOGY: Twenty-nine isolates from inpatients of Mãe de Deus Hospital that were identified and characterized for their susceptibility profile, vancomycin genotype, presence of esp gene, biofilm production, and clonal relationship were collected.  Patients' records were reviewed for clinical information. RESULTS: All isolates were identified as vancomycin/ampicillin resistant E. faecium carrying the vanA gene. Almost all were susceptible to gentamicin and streptomycin. Most patients died and were associated with a hemodialysis unit stay. All but the first isolate were clustered in a main clone. CONCLUSIONS: An important change in vancomycin-resistant enterococci was observed. Studies like this are necessary to monitor the dissemination of VRE, especially of some individual clones.

Presence of virulence factors in Enterococcus faecalis and Enterococcus faecium susceptible and resistant to vancomycin.

Despite the increasing importance of Enterococcus as opportunistic pathogens, their virulence factors are still poorly understood. This study determines the frequency of virulence factors in clinical and commensal Enterococcus isolates from inpatients in Porto Alegre, Brazil. Fifty Enterococcus isolates were analysed and the presence of the gelE, asa1 and esp genes was determined. Gelatinase activity and biofilm formation were also tested. The clonal relationships among the isolates were evaluated using pulsed-field gel electrophoresis. The asa1, gelE and esp genes were identified in 38%, 60% and 76% of all isolates, respectively. The first two genes were more prevalent in Enterococcus faecalis than in Enterococcus faecium, as was biofilm formation, which was associated with gelE and asa1 genes, but not with the esp gene. The presence of gelE and the activity of gelatinase were not fully concordant. No relationship was observed among any virulence factors and specific subclones of E. faecalis or E. faecium resistant to vancomycin. In conclusion, E. faecalis and E. faecium isolates showed significantly different patterns of virulence determinants. Neither the source of isolation nor the clonal relationship or vancomycin resistance influenced their distribution.

Presence of virulence factors in Enterococcus faecalis and Enterococcus faecium susceptible and resistant to vancomycin

Despite the increasing importance of Enterococcus as opportunistic pathogens, their virulence factors are still poorly understood. This study determines the frequency of virulence factors in clinical and commensal Enterococcus isolates from inpatients in Porto Alegre, Brazil. Fifty Enterococcus isolates were analysed and the presence of the gelE, asa1 and esp genes was determined. Gelatinase activity and biofilm formation were also tested. The clonal relationships among the isolates were evaluated using pulsed-field gel electrophoresis. The asa1, gelE and esp genes were identified in 38%, 60% and 76% of all isolates, respectively. The first two genes were more prevalent in Enterococcus faecalis than in Enterococcus faecium, as was biofilm formation, which was associated with gelE and asa1 genes, but not with the esp gene. The presence of gelE and the activity of gelatinase were not fully concordant. No relationship was observed among any virulence factors and specific subclones of E. faecalis or E. faecium resistant to vancomycin. In conclusion, E. faecalis and E. faecium isolates showed significantly different patterns of virulence determinants. Neither the source of isolation nor the clonal relationship or vancomycin resistance influenced their distribution.

The use of whole-cell protein profile analysis by SDS-PAGE as an accurate tool to identify species and subspecies of coagulase-negative staphylococci.

We used sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) as a tool to characterize coagulase-negative staphylococci (CoNS). Of 253 clinical isolates and 10 control strains, five species and four subspecies were analyzed. All the isolates were identified using conventional phenotypic tests and SDS-PAGE. Discrepant results between these methods, as well as less common species and subspecies, were confirmed by sodA and 16S rDNA gene sequencing. Intraspecies similarities, calculated by the Dice coefficient, were significantly higher when compared to interspecies similarities. The conventional method failed to identify eight (3.2%) molecularly defined and SDS-PAGE-determined isolates. Therefore, SDS-PAGE was able to discriminate between all unidentified or misidentified isolates using a phenotypic method. In addition, SDS-PAGE identified all atypical isolates using biochemistry and CoNS at the subspecies level.