In vitro and in vivo anti-Clostridioides difficile effect of a probiotic Bacillus amyloliquefaciens strain.

Clostridioides difficile infection (CDI) is a significant cause of hospital-acquired and antibiotic-mediated intestinal diseases and is a growing global public health concern. Overuse of antibiotics and their effect on normal intestinal flora has increased the incidence and severity of infections. Thus, the development of new, effective, and safe treatment options is a high priority. Here, we report a new probiotic strain, Bacillus amyloliquefaciens (BA PMC-80), and its in vitro/in vivo anti-C. difficile effect as a prospective novel candidate that can replace the use of conventional antibiotics. BA PMC-80 showed a significant anti-C. difficile effect on co-culture assay and its cell-free supernatant (CFS) also exhibited a considerable anti-C. difficile effect with an 89.06 µg/mL 50% minimal inhibitory concentration in broth microdilution assay. The CFS was stable and equally functional under different pH, heat, and proteinase treatments. It also exhibited a high sensitivity against current antibiotics and no toxicity in sub-chronic toxicity in hamsters. Finally, BA PMC-80 showed a moderate effect in a hamster CDI model with reduced infection severity and delayed death. However, further studies are required to optimize the treatment condition of the hamster CDI model for better efficacy and identify the antimicrobial compound produced by BA PMC-80.