Comparison of planktonic and biofilm-associated communities of Clostridium difficile and indigenous gut microbiota in a triple-stage chemostat gut model.
BACKGROUND
Biofilms are characteristic of some chronic or recurrent infections and this mode of growth tends to reduce treatment efficacy. Clostridium difficile infection (CDI) is associated with a high rate of recurrent symptomatic disease. The presence and behaviour of C. difficile within intestinal biofilms remains largely unexplored, but may factor in recurrent infection.


METHODS
A triple-stage chemostat gut model designed to facilitate the formation of intestinal biofilm was inoculated with a pooled human faecal emulsion. Bacterial populations were allowed to equilibrate before simulated CDI was induced by clindamycin (33.9 mg/L, four times daily, 7 days) and subsequently treated with vancomycin (125 mg/L, four times daily, 7 days). Indigenous gut microbiota, C. difficile total viable counts, spores, cytotoxin and antimicrobial activity in planktonic and biofilm communities were monitored during the 10 week experimental period.


RESULTS
Vancomycin successfully treated the initial episode of simulated CDI, but ∼18 days after therapy cessation, recurrent infection occurred. Germination, proliferation and toxin production were evident within planktonic communities in both initial and recurrent CDI. In contrast, sessile C. difficile remained in dormant spore form for the duration of the experiment. The effects of and recovery from clindamycin and vancomycin exposure for sessile populations was delayed compared with responses for planktonic bacteria.


CONCLUSIONS
Intestinal biofilms provide a potential reservoir for C. difficile spore persistence, possibly facilitating their dispersal into the gut lumen after therapeutic intervention, leading to recurrent infection. Therapeutic options for CDI could have increased efficacy if they are more effective against sessile C. difficile.
Leeds Institute of Biomedical and Clinical Sciences, Faculty of Medicine and Health, University of Leeds, Leeds LS2 9JT, UK.
Grace S
GS
Crowther
Leeds Institute of Biomedical and Clinical Sciences, Faculty of Medicine and Health, University of Leeds, Leeds LS2 9JT, UK.
Caroline H
CH
Chilton
Leeds Institute of Biomedical and Clinical Sciences, Faculty of Medicine and Health, University of Leeds, Leeds LS2 9JT, UK.
Sharie L
SL
Todhunter
Leeds Institute of Biomedical and Clinical Sciences, Faculty of Medicine and Health, University of Leeds, Leeds LS2 9JT, UK.
Scott
S
Nicholson
Department of Microbiology, Leeds Teaching Hospitals NHS Trust, The General Infirmary, Leeds LS1 3EX, UK.
Jane
J
Freeman
School of Life and Medical Sciences, Department of Human and Environmental Sciences, University of Hertfordshire, Hatfield AL10 9AB, UK.
Simon D
SD
Baines
Leeds Institute of Biomedical and Clinical Sciences, Faculty of Medicine and Health, University of Leeds, Leeds LS2 9JT, UK Department of Microbiology, Leeds Teaching Hospitals NHS Trust, The General Infirmary, Leeds LS1 3EX, UK mark.wilcox@leedsth.nhs.uk.
Mark H
MH
Wilcox
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018441:Biofilms / Q000254:growth & development*; D002981:Clindamycin / Q000494:pharmacology; D016360:Clostridioides difficile / Q000254:growth & development*; D005243:Feces / Q000382:microbiology; D007422:Intestines / Q000382:microbiology*; D064307:Microbiota / Q000187:drug effects; D010933:Plankton / Q000254:growth & development*; D013171:Spores, Bacterial / Q000254:growth & development; D014640:Vancomycin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D002981:Clindamycin; D014640:Vancomycin
recurrence; sessile; spores