Non-Toxigenic <i>Clostridioides difficile</i> Strain E4 (NTCD-E4) Prevents Establishment of Primary <i>C. difficile</i> Infection by Epidemic PCR Ribotype 027 in an In Vitro Human Gut Model
Perezimor Etifa,
César Rodríguez,
Céline Harmanus,
Ingrid M. J. G. Sanders,
Igor A. Sidorov,
Olufunmilayo A. Mohammed,
Emily Savage,
Andrew R. Timms,
Jane Freeman,
Wiep Klaas Smits,
Mark H. Wilcox,
Simon D. Baines
Affiliations
Perezimor Etifa
Department of Food and Nutritional Sciences, School of Chemistry, Food and Pharmacy, Reading RG6 6DZ, UK
César Rodríguez
Facultad de Microbiología & CIET, Universidad de Costa Rica, San Pedro 11501-2060, Costa Rica
Céline Harmanus
Leiden University Medical Center, Department of Medical Microbiology, Albinusdreef, P.O. Box 9600, 2300 RC Leiden, The Netherlands
Ingrid M. J. G. Sanders
Leiden University Medical Center, Department of Medical Microbiology, Albinusdreef, P.O. Box 9600, 2300 RC Leiden, The Netherlands
Igor A. Sidorov
Leiden University Medical Center, Department of Medical Microbiology, Albinusdreef, P.O. Box 9600, 2300 RC Leiden, The Netherlands
Olufunmilayo A. Mohammed
Department of Clinical, Pharmaceutical and Biological Sciences, School of Life and Medical Sciences, University of Hertfordshire, Hatfield AL10 9AB, UK
Emily Savage
Department of Clinical, Pharmaceutical and Biological Sciences, School of Life and Medical Sciences, University of Hertfordshire, Hatfield AL10 9AB, UK
Andrew R. Timms
Department of Clinical, Pharmaceutical and Biological Sciences, School of Life and Medical Sciences, University of Hertfordshire, Hatfield AL10 9AB, UK
Jane Freeman
Healthcare Associated Infections Research Group, Leeds Institute of Medical Research, University of Leeds, Leeds LS2 9JT, UK
Wiep Klaas Smits
Leiden University Medical Center, Department of Medical Microbiology, Albinusdreef, P.O. Box 9600, 2300 RC Leiden, The Netherlands
Mark H. Wilcox
Healthcare Associated Infections Research Group, Leeds Institute of Medical Research, University of Leeds, Leeds LS2 9JT, UK
Simon D. Baines
Department of Clinical, Pharmaceutical and Biological Sciences, School of Life and Medical Sciences, University of Hertfordshire, Hatfield AL10 9AB, UK
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 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.
