title: Trends in antimicrobial resistance among clinical isolates of enterococci in a Brazilian tertiary hospital: a 4-year study.
abstract: BACKGROUND
  In the past two decades members of the genus Enterococcus have emerged as important nosocomial pathogens worldwide. This study prospectively analyzed the distribution of species and trends in antimicrobial resistance among clinical isolates of enterococci in a Brazilian tertiary hospital from 2006-2009.
  
  
  METHODS
  Enterococcal species were identified by conventional biochemical tests. The antimicrobial susceptibility profile was performed by disk diffusion in accordance with the Clinical and Laboratory Standards Institute (CLSI). A screening test for vancomycin was also performed. Minimal inhibitory concentration (MIC) for vancomycin was determined using the broth dilution method. Molecular assays were used to confirm speciation and genotype of vancomycin-resistant enterococci (VRE).
  
  
  RESULTS
  A total of 324 non-repetitive enterococcal isolates were recovered, of which 87% were E. faecalis and 10.8% E. faecium. The incidence of E. faecium per 1,000 admissions increased significantly (p < 0.001) from 0.3 in 2006 to 2.3 in 2009. The VRE rate also increased over time from 2.5% to 15.5% (p < 0.001). All VRE expressed high-level resistance to vancomycin (MIC >256 µg/ mL) and harbored vanA genes. The majority (89.5%) of VRE belonged to E. faecium species, which were characteristically resistant to ampicillin and quinolones. Overall, ampicillin resistance rate increased significantly from 2.5% to 21.4% from 2006-2009. Resistance rates for gentamicin, chloramphenicol, tetracycline, and erythromycin significantly decreased over time, although they remained high. Quinolones resistance rates were high and did not change significantly over time.
  
  
  CONCLUSIONS
  The data obtained show a significant increasing trend in the incidence of E. faecium resistant to ampicillin and vancomycin.
authors.affiliation: Departamento de Ciências Biológicas, Universidade Federal do Triângulo Mineiro, Uberaba, MG, Brasil.
authors.forename: Natália
authors.initials: N
authors.lastname: Conceição
authors.forename: Cristina da Cunha Hueb Barata de
authors.initials: Cda C
authors.lastname: Oliveira
authors.forename: Paulo Roberto da
authors.initials: PR
authors.lastname: Silva
authors.forename: Bárbara Godoi Melo
authors.initials: BG
authors.lastname: Avila
authors.forename: Adriana Gonçalves de
authors.initials: AG
authors.lastname: Oliveira
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001938:Brazil; D003428:Cross Infection / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics*; D024881:Drug Resistance, Bacterial; D016983:Enterococcus / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D005838:Genotype; D006801:Humans; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011446:Prospective Studies
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial