title: Incidence of virulence determinants in clinical Enterococcus faecalis and Enterococcus faecium isolates collected in Bulgaria.
abstract: OBJECTIVE
  To evaluate the prevalence of some virulence genes among 510 clinical Enterococcus spp. isolates and to assess the association of those genes with the species, infection site, and patient group (inpatients/outpatients).
  
  
  METHODS
  Adhesins genes (aggregation substances agg and asa1 of Enterococcus faecalis and Enterococcus faecium, respectively), enterococcal surface protein (esp), endocarditis-specific antigen A (efaA), collagen-binding proteins (ace/acm)); invasins (hyaluronidase (hyl) and gelatinase (gelE)); cytotoxines (activation of cytolysin (cylA) in E. faecalis); and modulators of the host immunity and inflammation (enhanced expression pheromone (eep) in E. faecalis) were detected by polymerase chain reaction.
  
  
  RESULTS
  The overall prevalence was: esp - 44.3%, agg/asa1 - 38.4%, ace/acm - 64.3%, efaA - 85.9%, eep - 69.4%, gelE - 64.3%, hyl - 25.1%, and cylA - 47.1%. E. faecalis isolates had significantly higher frequency of adhesin genes (esp and agg/asa1) and gelatinase in comparison to E. faecium. Multiple virulence genes in E. faecalis were significantly more prevalent than in E. faecium isolates. Domination of E. faecium with or without only one gene compared to the isolates of E. faecalis were found. Enterococcus spp. isolates obtained from outpatients compared to inpatients isolates had significantly higher frequency of agg/asa1, eep, gelE and cylA. Some adhesins genes (esp, agg/asa1 and efaA) had higher prevalence among the non-invasive Enterococcus spp. isolates compared to those causing invasive bacteremia, while ace/acm revealed higher dissemination in isolates causing invasive infections compared to non-invasive isolates.
  
  
  CONCLUSIONS
  Most E. faecalis attaches to abiotic surfaces in hospital environment, which correlates with higher prevalence of gene encoding for virulence factors involved in biofilm formation, such as enterococcal surface protein, aggregation substance, and gelatinase. The intestinal tract is an important reservoir for opportunistic enterococcal pathogens and allows them to access infectious sites through different virulence factors, demonstrated in outpatient isolates in this study.
authors: Department of Medical Microbiology, Faculty of Medicine, Medical University of Sofia, Bulgaria. Electronic address: dr.strateva@abv.bg.
authors: Tanya
authors: T
authors: Strateva
authors: Department of Medical Microbiology, Faculty of Medicine, Medical University of Sofia, Bulgaria.
authors: Daniela
authors: D
authors: Atanasova
authors: Laboratory of Microbiology, Department of Military Epidemiology and Hygiene, Military Medical Academy, Sofia, Bulgaria.
authors: Encho
authors: E
authors: Savov
authors: Pediatric Clinic, Alexandrovska University Hospital, Faculty of Medicine, Medical University of Sofia, Bulgaria.
authors: Guergana
authors: G
authors: Petrova
authors: Department of Medical Microbiology, Faculty of Medicine, Medical University of Sofia, Bulgaria.
authors: Ivan
authors: I
authors: Mitov
mesh_terms: D002031:Bulgaria; D016521:Electrophoresis, Gel, Pulsed-Field; D013293:Enterococcus faecalis / Q000472:pathogenicity*; D016984:Enterococcus faecium / Q000472:pathogenicity*; D006801:Humans; D015994:Incidence; D016133:Polymerase Chain Reaction; D014774:Virulence / Q000235:genetics*; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D037521:Virulence Factors
keywords: Enterococcus faecalis; Enterococcus faecium; Prevalence; Virulence genes