Multilocus sequence typing and analysis of putative virulence factors in vancomycin-resistant and vancomycin-sensitive Enterococcus faecium isolates from Brazil

ABSTRACTEnterococci are leading causes of hospital-acquired infections that are often difficult to treat because of high-level aminoglycoside and glycopeptide resistance. Vancomycin-resistant enterococci are a global problem, and have been isolated with increasing frequency in hospitals in Brazil. The objective of this study was to determine the genetic relatedness of vancomycin-resistant Enterococcus faecium (VREFM) and vancomycin-sensitive E. faecium (VSEFM) isolated from human infections and faecal sources in Brazil, and to compare these isolates with those from domesticated animals. Isolates (n = 56) were classified by multilocus sequence typing (MLST) and assessed for putative virulence traits. The acm gene was detected in 98% of all isolates. The 56 isolates studied comprised 26 different MLST types. VSEFM isolates from the faeces of pigs were found to be distinct from all human isolates characterised previously by MLST, and were assigned new sequence type (ST) numbers. VREFM isolates were represented by four different STs (ST-114, ST-17, ST-281, ST-50). Among the 26 STs identified in this study, eBURST detected three groups of STs with related allelic profiles, and 19 unrelated STs. Among E. faecium isolates from Brazil, the esp gene was restricted to vancomycin-resistant isolates. Furthermore, isolates classified as ST-17 by MLST, an epidemic strain type isolated internationally with the purK-1 gene, were found among VREFM isolates from Brazil that also harboured the esp and hyl genes

Enterococcus gallinarum carrying the vanA gene cluster: first report in Brazil

In 2000, Enterococcus faecalis resistant to vancomycin was first reported at a tertiary hospital in Porto Alegre, southern Brazil. The resistance spread to other hospitals and surveillance programs were established by hospital infection committees to prevent the spread of vancomycin-resistant enterococci. In February 2002, an isolate initially identified at the genus level as Enterococcus was obtained by surveillance culture (rectal swab) from a patient admitted to a hospital for treatment of septic arthritis in the shoulder. The isolate proved to be resistant to vancomycin by the disc diffusion method and confirmed by an E-test resulting in a minimal inhibitory concentration of > or = 256 µg/ml. This isolate was sent to a reference laboratory (Laboratório Especial de Bacteriologia e Epidemiologia Molecular, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, USP) for further study and proved to be an E. gallinarum by the polymerase chain reaction (PCR) using specific primers for the species. Due to the phenotype of unusually high vancomycin resistance, the isolate presumably had the resistance genes (vanA and vanB) and this was confirmed by PCR, which indicated the presence of the vanA gene. A 10.8-kb Tn1546-related transposon was also identified by long-PCR. Interspecies transfer of the vancomycin-resistance gene from the donor E. gallinarum was performed in a successful conjugation experiment in vitro, using E. faecium GE-1 and E. faecalis JH22 as receptors. This is the first report of the detection of a vanA determinant naturally acquired by E. gallinarum in Brazil, indicating the importance of characterizing VRE by both phenotype and genotype methods