Open Access In Vitro Evaluation of Antimicrobial Activity of Lactic Acid Bacteria against Clostridium difficile

Clostridium difficile infection (CDI) has become a significant threat to public health. Although broad-spec-trum antibiotic therapy is the primary treatment option for CDI, its use has evident limitations. Probiotics have been proved to be effective in the treatment of CDI and are a promising therapeutic option for CDI. In this study, 4 strains of lactic acid bacteria (LAB), namely, Lactobacillus rhamnosus (LR5), Lactococ-cuslactis (SL3), Bifidobacterium breve (BR3), and Bifidobacterium lactis (BL3) were evaluated for their anti-C. difficile activity. Co-culture incubation of C. difficile (106 and 1010 CFU/ml) with each strain of LAB indicated that SL3 possessed the highest antimicrobial activity over a 24-hr period. The cell-free supernatants of the 4 LAB strains exhibited MIC50 values between 0.424 mg/ml (SL3) and 1.318 (BR3) mg/ml. These results may provide a basis for alternative therapies for the treatment of C. difficile-associ-ated gut disorders. Key words: Clostridium difficile infection, lactic acid bacteria, antimicrobial activity, cell-free supernatan