Safety assessment of the candidate oral probiotic Lactobacillus crispatus YIT 12319: Analysis of antibiotic resistance and virulence-associated genes.

Lactobacillus crispatus YIT 12319 (LcY) was isolated from the oral cavity of a healthy subject as a new candidate probiotic with potential benefits for oral health. As a safety assessment of LcY, we performed an antibiotic susceptibility test and virulence-associated gene analysis using a draft genome sequence. Susceptibility to 15 antibiotics was analyzed according to the standard method of the International Dairy Federation/International Organization for Standardization, as recommended by the European Food Safety Authority. The results showed that the minimum inhibitory concentrations of LcY were not higher than those of other L. crispatus strains, which have not acquired resistance to any antibiotics, suggesting that LcY had no externally acquired transmissible antibiotic resistance genes. Analysis of virulence-associated genes using the draft genome of LcY found that there were fewer potential virulence-associated genes in LcY than in other probiotics. These findings suggest that LcY could be a candidate probiotic based on its safety profile.