Antibacterial activity of intestinal Lactobacillus sp.on the growth of Clostridium difficile

Indigenous intestinal microflora (including lactobacilli) has an important role in protection against Clostridium difficile infection. To assess in vitro interaction between lactobacilli and C. difficile,antagonistic activity of 4 intestinal Lactobacillus spp. strains against 15 pathogenic C. difficile strains was determined. Phenotypic properties of C. difficile strains [production of short-chain fatty acids (SCFAs) and toxin A, and antimicrobial susceptibility] and lactobacilli (production of SCFAs and H2O2) were investigated. Three lactobacilli (Lactobacillus paracasei and Lactobacillus plantarum species and L. Acidophilus) were antagonistic to all C. difficile strains, and one showed no antagonistic activity. This antagonistic activity was strain-specific and seemed to correlate with H2O2 and lactic acid production. C. difficile strains that were more sensitive to lactobacilli usually produced higher toxin levels and more SCFAs, and were more resistant to antibiotics, than strains that were resistant to lactobacilli . Compatibility of C. difficile strain properties (resistance to lactobacilli or antibiotics) with intestinal microecological conditions (e.g. presence of antagonistic lactobacilli, concentration of antibiotics) may determine expression of disease.