Virulence Gene’s Relationship With Biofilm Formation and Detection of aac (6’)/aph (2”) in Enterococcus faecalis Isolated From Patients With Urinary Tract Infection

Background: Enterococcus faecalis is part of the human gastrointestinal tract normal flora, which is considered as a major cause of nosocomial infections. One of the important virulence factors of enterococci is their ability to biofilms formation. Objectives: We investigated the potential relationships between biofilm formation and prevalence of virulence genes (asa1, esp, cylA, and gelE/sprE), and antimicrobial resistance genes (aac (6')/aph (2") in Enterococcus faecalis isolated from patients with urinary tract infection. Patients and Methods: In this survey 95 E. faecalis isolates from patients with urinary tract infections staying at Shahid Beheshti hospital in Kashan, Iran, between 2007 and 2008 were studied. We analyzed the prevalence of genes encoding virulence factors (asa1, esp, cylA and gelE/sprE), and antimicrobial resistance genes [(aac (6')/aph (2")] by PCR. In addition, the production of biofilm and extracellular enzymes, hemolysin (Hln) and Gelatinase were examined. Results: The asa1,(aac (6')/aph (2"), esp, cylA, and gelE/sprE were detected in 94.7%, 68.4%, 61.1%, 50.5% and 21.1% of E. faecalis isolates, respectively. The hemolysin production and gelatinase activity were seen in 44.2% and 20% of isolates, respectively. 16.8% of E. faecalis isolates showed strong and 83.2% exhibited weak biofilm formation. The percentages of genes encoding virulence factors in E. faecalis which had the ability of strong biofilm formation were as follows: gelE/sprE 25%, esp22.4%, (aac (6')/aph (2") 18.5%, asa1 16.7% and cylA 14.6%. The presence of both aac (6')/aph (2") and esp positive act as a risk factor for biofilm formation (P value < 0.001). Conclusions: There was a significant relationship between biofilm formation and possession of esp and aac (6')/aph (2") genes. There was no evidence between biofilm formation and presence of any other gene. Enterococcal infections associated with biofilm formation have been a serious problem in recent years.