Towards a compatible probiotic-antibiotic combination therapy: assessment of antimicrobial resistance in the Japanese probiotics

Aim: To determine the antimicrobial resistance of the Japanese probiotics available in the market without a pharmacist's supervision. Methods and Results: A total of 43 isolates were obtained from 40 samples of probiotics (30 dairy products and 10 products in tablet form). Isolates were identified using 16S rRNA gene sequencing and tested for their susceptibility to 14 antimicrobials. They were screened using PCR for some antibiotic resistance genes. Inactivation of cefepime, clarithromycin and vancomycin by different inocula of 11 strains was evaluated using the antibiotic inactivation bioassay. None of the dairy probiotics showed a level of constitutive resistance or carried inducible resistance genes, making them suitable to be administrated with macrolides. Among the probiotics in tablet form only Enterococcus faecium strains carrying the msrC gene showed an MIC90 of 4 mu g ml-1. Extended-spectrum beta-lactams, tetracyclines and ampicillin exhibited powerful germicidal activity against the vast majority of the probiotic strains. Conclusions: There is a limited choice of the Japanese probiotics that can be administered with clinically used antibiotics. Significance and Impact of the Study: Japanese probiotics are widely distributed all over the world. Through the findings of our study, we have attempted to provide guidance for clinicians interested in using the Japanese probiotics in combination with antibiotics.