Study on Biofilm Formation Among Enterococcus Isolates and Association With Their Antibiotic Resistance Patterns

Background Enterococci are a part of the normal intestinal flora of humans. They have emerged as one of the leading causes of nosocomial infection. The evolved antibiotic resistance mechanisms coupled with the virulence properties of enterococci have made it a successful pathogen. Aim This study aimed to determine the ability of biofilm formation among the clinical enterococci isolates and the antimicrobial resistance pattern of the strains. Materials and methods Clinical samples of patients who attended Saveetha Medical College and Hospital, Chennai, India, over six months. Identification and characterization of Enterococcus species were done using various biochemical tests. Antibiotic susceptibility patterns for each isolate were performed using the Kirby- Bauer disc diffusion method. Results The formation of biofilm formation was detected using the microtiter plate method. In total, 90 Enterococcus species were isolated; Enterococcus faecalis were 63 (70%), Enterococcus faecium were 25 (28%) and Enterococcus gallinarum were 2 (2%)independently. E. faecalis displayed advanced resistance rates compared to other Enterococcus species. Resistance against penicillin was found in 42 strains (47%) and resistance to ampicillin was observed in 39 strains (43%). This was followed by resistance to high-level gentamicin in 35 strains (39%) and resistance to ciprofloxacin in 32 strains (36%). Resistance to vancomycin and linezolid also were noted in some strains. Conclusion Our results indicate that E. faecalis exhibits an increasing rate of antimicrobial resistance but lower biofilm conformation. The unique traits of E. faecalis raise concerns for the associated infections, especially hospital-acquired infections.