Characterization ofC. difficilestrains isolated from companion animals and the associated changes in the host fecal microbiota

Abstract

AbstractBackgroundClostridioides difficileis an enteric pathogen historically known to cause hospital associated (HA)-infections in humans. A major risk factor for CDI in humans is antibiotic usage as it alters the gut microbiota and there is a loss of colonization resistance againstC. difficile. In recent years there has been an increase in community associated (CA)-C. difficileinfection that does not have the same risk factors as HA-CDI. Potential sources of CA-CDI have been proposed and include animals, food, water, and the environment, however these sources remain poorly investigated. Here, we define the prevalence ofC. difficilestrains found in different companion animals (canines, felines, and equines) to investigate a potential zoonotic link.C. difficilestrains were identified by toxin gene profiling, fluorescent PCR ribotyping, and antimicrobial susceptibility testing. 16s rRNA gene sequencing was done on animal feces to investigate the relationship between the presence ofC. difficileand the gut microbiota in different hosts.ResultsHere, we show thatC. difficilewas recovered from 20.9% of samples (42/201), which included 33 canines, 2 felines, and 7 equines. Over 69% (29/42) of the isolates were toxigenic and belonged to 14 different ribotypes, with overlap between HA- and CA-CDI cases in humans. The presence ofC. difficileresults in a shift in the fecal microbial community structure in both canines and equines. Commensal ClostridiaC. hiranoniswas negatively associated withC. difficilein canines. Further experimentation showed a clear antagonistic relationship between the two strainsin vitro, suggesting that commensalClostridiamight play a role in colonization resistance againstC. difficilein different hosts.ConclusionsIn this study we investigated a potentially important source ofC. difficiletransmission: the companion animal population.C. difficilecarriage was common in dogs, cats, and horses.C. difficileisolates from companion animals included many of the same ribotypes known to cause HA- and CA-CDI in humans, and had similar antimicrobial resistance profiles as those isolated from human populations. These data contribute to our understanding of non-hospital exposure toC. difficilein the human population and suggest new avenues for reducingC. difficileprevalence in companion animals and, perhaps, thereby reducing CA-CDI in humans.