Clostridioides difficile infection (CDI) remains a significant healthcare burden. Non-toxigenic C. difficile (NTCD) strains have shown a benefit in preventing porcine enteritis and in human... Show moreClostridioides difficile infection (CDI) remains a significant healthcare burden. Non-toxigenic C. difficile (NTCD) strains have shown a benefit in preventing porcine enteritis and in human recurrent CDI. In this study, we evaluated the efficacy of metronidazole-resistant NTCD-E4 in preventing CDI facilitated by a range of antimicrobials in an in vitro human gut model. NTCD-E4 spores (at a dose of 10(7)) were instilled 7 days before a clinical ribotype (RT) 027 (at the same dose) strain (210). In separate experiments, four different antimicrobials were used to perturb gut microbiotas; bacterial populations and cytotoxin production were determined using viable counting and Vero cell cytotoxicity, respectively. RT027 and NTCD-E4 proliferated in the in vitro model when inoculated singly, with RT027 demonstrating high-level cytotoxin (3-5-log(10)-relative units) production. In experiments where the gut model was pre-inoculated with NTCD-E4, RT027 was remained quiescent and failed to produce cytotoxins. NTCD-E4 showed mutations in hsmA and a gene homologous to CD196-1331, previously linked to medium-dependent metronidazole resistance, but lacked other metronidazole resistance determinants. This study showed that RT027 was unable to elicit simulated infection in the presence of NTCD-E4 following stimulation by four different antimicrobials. These data complement animal and clinical studies in suggesting NTCD offer prophylactic potential in the management of human CDI. Show less
Clostridioides difficile infection (CDI) remains a significant healthcare burden. Non-toxigenicC. difficile (NTCD) strains have shown a benefit in preventing porcine enteritis and in human... Show moreClostridioides difficile infection (CDI) remains a significant healthcare burden. Non-toxigenicC. difficile (NTCD) strains have shown a benefit in preventing porcine enteritis and in human recurrentCDI. In this study, we evaluated the efficacy of metronidazole-resistant NTCD-E4 in preventingCDI facilitated by a range of antimicrobials in an in vitro human gut model. NTCD-E4 spores (ata dose of 107) were instilled 7 days before a clinical ribotype (RT) 027 (at the same dose) strain(210). In separate experiments, four different antimicrobials were used to perturb gut microbiotas;bacterial populations and cytotoxin production were determined using viable counting and Vero cellcytotoxicity, respectively. RT027 and NTCD-E4 proliferated in the in vitro model when inoculatedsingly, with RT027 demonstrating high-level cytotoxin (3-5-log10-relative units) production. Inexperiments where the gut model was pre-inoculated with NTCD-E4, RT027 was remained quiescentand failed to produce cytotoxins. NTCD-E4 showed mutations in hsmA and a gene homologous toCD196-1331, previously linked to medium-dependent metronidazole resistance, but lacked othermetronidazole resistance determinants. This study showed that RT027 was unable to elicit simulatedinfection in the presence of NTCD-E4 following stimulation by four different antimicrobials. Thesedata complement animal and clinical studies in suggesting NTCD offer prophylactic potential in themanagement of human CDI. Show less
Clostridioides difficile infection (CDI) remains a significant healthcare burden. Non-toxigenic C. difficile (NTCD) strains have shown a benefit in preventing porcine enteritis and in human... Show moreClostridioides difficile infection (CDI) remains a significant healthcare burden. Non-toxigenic C. difficile (NTCD) strains have shown a benefit in preventing porcine enteritis and in human recurrent CDI. In this study, we evaluated the efficacy of metronidazole-resistant NTCD-E4 in preventing CDI facilitated by a range of antimicrobials in an in vitro human gut model. NTCD-E4 spores (at a dose of 107) were instilled 7 days before a clinical ribotype (RT) 027 (at the same dose) strain (210). In separate experiments, four different antimicrobials were used to perturb gut microbiotas; bacterial populations and cytotoxin production were determined using viable counting and Vero cell cytotoxicity, respectively. RT027 and NTCD-E4 proliferated in the in vitro model when inoculated singly, with RT027 demonstrating high-level cytotoxin (3-5-log10-relative units) production. In experiments where the gut model was pre-inoculated with NTCD-E4, RT027 was remained quiescent and failed to produce cytotoxins. NTCD-E4 showed mutations in hsmA and a gene homologous to CD196-1331, previously linked to medium-dependent metronidazole resistance, but lacked other metronidazole resistance determinants. This study showed that RT027 was unable to elicit simulated infection in the presence of NTCD-E4 following stimulation by four different antimicrobials. These data complement animal and clinical studies in suggesting NTCD offer prophylactic potential in the management of human CDI. Show less
