Determination of antibiotics resistance and biofilm formation in Enterococcus faecalis isolated from different clinical specimens

Background: E. faecalis has a clinical importance closely related to its ability to resist many antibiotics, which enhances the opportunity of colonization and infection. E. faecalis can form a robust biofilm, which further contributes to increased antimicrobial resistance. Objectives: This study aimed to detect the resistance patterns of antibiotics and the ability to form biofilm among clinical isolates of E.faecalis. Methods: A total of sixty E. faecalis isolates were obtained from different clinical specimens, including urine, blood, urethral discharge, high vaginal swab (H.V.S), skin, wound, and ear swabs, fluid, bronchoalveolar lavage (BAL), and dental root canal specimens. All isolates were identified using biochemical tests and the VITEK-2 Compact system and were tested for antimicrobial susceptibility using the VITEK-2 Compact system and the Kirby–Bauer disc diffusion method. Biofilm production was evaluated using the Congo red agar (CRA) method and the tissue culture plate (TCP) assay. Results: Most isolates were recovered from urine samples (56.7%), followed by dental root canal samples (15%), HVS (6.7%), blood and wound swabs (5% each), skin and BAL (3.3% each), and fluid, urethral discharge for males, and ear swabs (1.7% each). The hemolysis activity was mainly alpha-hemolysis (43.3%), followed by beta-hemolysis (41.7%) and gamma-hemolysis (15%). A significantly higher proportion of biofilm formation was detected by tissue culture plate (TCP) (35%) compared with CRA (20%).High resistance rates were observed for doxycycline (50%), followed by erythromycin (41.7%), rifampicin (40%), ciprofloxacin (38.3%), levofloxacin (36.7%), norfloxacin (25%), chloramphenicol (23.3%), vancomycin (13.3%), ampicillin (6.7%), penicillin, linezolid, and teicoplanin (3.3% each), and nitrofurantoin and tigecycline (1.7% each). Conclusion: E. faecalis has the ability to colonize and infect various body sites. Three stages of biofilm production (weak, moderate, and strong) and high resistance rate to some antibiotics were demonstrated, indicating the clinical challenge of this pathogen.