Virulence factors, biofilm formation and antibiotic resistance pattern in Enterococcus faecalis and Enterococcus faecium isolated from clinical and commensal human samples in Isfahan, Iran

Abstract

Background. The aim of this study was to determine and compare antibiotic resistance profile, biofilm formation ability and frequency of agg and ace genes in Enterococcus spp strains isolated from patients and healthy individuals. Methods. A total of 90 non-duplicate Enterococcus spp isolates were isolated from patients and healthy individuals. Antibiotic susceptibility pattern was determined by disk diffitsion and E-test method. Virulence genes and two species of enterococci were determined by PCR amplification. The capacity of biofilm formation was also evaluated by micmtiter plate technique. Results. E. faecalis was the predominant species among our clinical isolates (80). The prevalence of agg and ace genes was 37.8 and 73.3 in clinical and 8.9 and 11.1 in "healthy" samples, respectively. The rate of Multiple Drug Resistant strains was 73.3 and 11.1 in clinical and "healthy" isolates, respectively. The ability of biofilm formation was significantly higher in clinical compared to "healthy" isolates (100 vs 75.6, P < 0.05). Conclusions. The frequency of ace and agg genes, antibiotic resistance and biofilm formation ability were significantly higher in clinical than in "healthy" isolates (P < 0.05). Existence of agg and ace genes, biofilm formation and antibiotic resistance among the healthy enterococci isolates has a special importance since, in case these strains spread through clinical environments or reach water sources, this issue can be considered as a risk factor for health and sanitation of society.