RÉSUMÉ
We studied the genetic relationships between vancomycin-susceptible (n = 11) and -resistant Enterococcus faecium (VRE, n = 20) recovered from Brazil using a multilocus sequence typing (MLST) scheme. Grouping of allelic profiles revealed six clusters of related sequence types (STs) that differ in no more than two of the seven alleles. Of these, one cluster harbored 16 of the 20 isolates recovered during the first VRE outbreak in Brazil. The ampicillin and gentamicin resistance profiles were stable in the isolates that clustered within the groups I-III. Comparison with the allelic profiles of 139 E. faecium from different geographical regions and origins found in the international database http://www.mlst.net revealed that the Brazilian outbreak clone did not cluster in the previously named complex-17. This genetic complex contains hospital epidemic and clinical isolates recovered from different countries and continents. Twenty two of the 31 Brazilian isolates, including the VRE outbreak clone, clustered apart from the E. faecium isolates from the database, suggesting that these Brazilian isolates have a distinct evolutionary history.
Sujet(s)
Infection croisée/microbiologie , Résistance bactérienne aux médicaments/génétique , Enterococcus faecium/effets des médicaments et des substances chimiques , Enterococcus faecium/génétique , Infections bactériennes à Gram positif/microbiologie , Allèles , Résistance à l'ampicilline/génétique , Brésil/épidémiologie , Numération de colonies microbiennes , Infection croisée/épidémiologie , Épidémies de maladies , Évolution moléculaire , Gentamicine/pharmacologie , Infections bactériennes à Gram positif/épidémiologie , Hôpitaux , Humains , Analyse de séquence d'ADN , Résistance à la vancomycine/génétiqueRÉSUMÉ
Vancomycin-resistant enterococci (VRE) have caused hospital outbreaks worldwide, and the vancomycin-resistance gene (vanA) has crossed genus boundaries to methicillin-resistant Staphylococcus aureus. Spread of VRE, therefore, represents an immediate threat for patient care and creates a reservoir of mobile resistance genes for other, more virulent pathogens. Evolutionary genetics, population structure, and geographic distribution of 411 VRE and vancomycin-susceptible Enterococcus faecium isolates, recovered from human and nonhuman sources and community and hospital reservoirs in 5 continents, identified a genetic lineage of E. faecium (complex-17) that has spread globally. This lineage is characterized by 1) ampicillin resistance, 2) a pathogenicity island, and 3) an association with hospital outbreaks. Complex-17 is an example of cumulative evolutionary processes that improved the relative fitness of bacteria in hospital environments. Preventing further spread of this epidemic E. faecium subpopulation is critical, and efforts should focus on the early disclosure of ampicillin-resistant complex-17 strains.
Sujet(s)
Infection croisée/transmission , Enterococcus faecium/effets des médicaments et des substances chimiques , Infections bactériennes à Gram positif/transmission , Résistance à la vancomycine , Afrique/épidémiologie , Animaux , Australie/épidémiologie , Protéines bactériennes/génétique , Protéines bactériennes/métabolisme , Chats , Bovins , Infection croisée/épidémiologie , Infection croisée/microbiologie , Chiens , Enterococcus faecium/classification , Enterococcus faecium/génétique , Enterococcus faecium/pathogénicité , Europe/épidémiologie , Évolution moléculaire , Infections bactériennes à Gram positif/épidémiologie , Infections bactériennes à Gram positif/microbiologie , Humains , Amérique du Nord/épidémiologie , Résistance aux pénicillines , Recombinaison génétique , Amérique du Sud/épidémiologieRÉSUMÉ
Multilocus variable-number tandem-repeat analysis (MLVA) for seven genomic loci was developed for Enterococcus faecalis. MLVA and pulsed-field gel electrophoresis (PFGE) resulted in 37 and 31 genotypes among 83 strains, respectively. Both typing schemes were highly concordant (90.4%). MLVA is an excellent alternative to PFGE.