Incidence of virulence determinants in clinical Enterococcus faecalis and Enterococcus faecium isolates collected in Bulgaria

Abstract Objectives 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. Conclusion 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.

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.

Mecanismos de resistência do enterococcus / Mechanisms of resistance of the enterococcus

Os Enterococos são cocos gram-positivos com baixo potencial de causar doenças. No entanto, tornaram-se temidos nas últimas décadas devido ao desenvolvimento de cepas bastante resistentes aos aminoglicosídeos, à ampicilina, penicilina e vancomicina. Os locais de infecções enterocócicas mais comuns são as vias urinárias e a corrente sangüínea. O controle e a prevenção dessas infecções é difícil devido ao elevado grau de resistência, o que torna importante a restrição da antibioticoterapia e o controle de pacientes infectados para reduzir a disseminação dessas bactérias

Infección nosocomial por enterococo resistente a la vancomicina: características clínico-epidemiológicas y factores de riesgo / Nosocomial infection by Vancomicin resistant Enterococcus: Clinical - epidemiological characteristics and risk factors

Objetivo: caracterizar clínica y epidemiológicamente, y establecer los factores de riesgo de un brote de infección nosocomial por Enterococcus faecium resistente a vancomicina en el HUSVP de Medellín. Metodología: se realizó un estudio con una fase descriptiva (27 casos) y un diseño tipo casos (27) y controles (54). Resultados: los 27 casos de E. faecium tuvieron un alto nivel de resistencia a vancomicina (128 ug/ml), y además fueron resitentes a teicoplanina, ampicilina, penicilina, ciprofloxacina, y gentamicina y estreptomicina de alto nivel. En el 67 por ciento de los casos se interpretó cono infección; el 33 por ciento de las cepas se aislaron de orina y el 22 por ciento de cavidad abdominal. Los factores de riesgo asociados fueron la insuficiencia renal (RD 12.6), nutrición parenteral total (RD 6.2), la cirugía abdominal (RD 4.1), uso previo de metronidazol (RD 19.5) ceftazidima (RD 15.9), cefotaxima (RD 12.6), imipenem (RD 11.6), ciproflaxina (RD 6.7), vancomicina (RD 5.4), ampicilina/sulbactam (RD 4.4), días estancia (p=0.004), días entre el ingreso y la infección (p=0.0007), número de cirugias (p=0.0004) y número de antibióticos previos (p=0.00005). Conclusiones: esta es la primera epidemia de ERV que se publica en Colombia, con un análisis clínico, epidemiológico y de factores de riesgo, y nos muestra una realidad ya vivida por otros países y de muy difícil manejo, y nos alerta sobre la posibilidad de aparición de Staphylococcus aureus con sensibilidad disminuida a la vancomicina