Antimicrobial Susceptibility of Probiotic Lactic Acid Bacteria, Enterococcus faecalis FK-23

Abstract

Enterococcus faecalis FK-23, isolated from human intestinal tract, was used widely as probiotics. However, vancomycin-resistant Enterococci (VRE) containing vancomycin-resistant E. faecalis also exist, and appearing of VRE has serious problems in the world. In this study, we investigated antimicrobial susceptibility of E. faecalis FK-23 and vancomycin resistance genes prevalence in the organisms. E. faecalis FK-23 was susceptible to various antibiotics such as benzylpenicillin, aminobenzylpenicillin, gentamicin, erythromycin, minocyclin, levofloxacin and vancomycin, and showed intermediate resistance to cefazolin and ciprofloxacin by Kirby-Bauer disk method. Minimal inhibitory concentration (MIC) of vancomycin to E. faecalis FK-23 showed 2 μg/ml by using agar dilution method. Vancomycin resistance genes, such as vanA, vanB, vanC-1, vanC-2, and vanC-3 were not detected in E. faecalis FK-23 by using PCR method. These results suggest that E. faecalis FK-23 is safety for using probiotics.