Clostridioides difficile infection and One Health: An equine perspective

Clostridioides (Clostridium) difficile presents a significant health risk to humans and animals. The complexity of the bacterial–host interaction affecting pathogenesis and disease development creates an ongoing challenge for epidemiological studies, control strategies and prevention planning. The recent emergence of human disease caused by strains of C. difficile found in animals adds to mounting evidence that C. difficile infection (CDI) may be a zoonosis. In equine populations, C. difficile is a known cause of diarrhoea and gastrointestinal inflammation, with considerable mortality and morbidity. This has a significant impact on both the well-being of the animal and, in the case of performance and production animals, it may have an adverse economic impact on relevant industries. While C. difficile is regularly isolated from horses, many questions remain regarding the impact of asymptomatic carriage as well as optimization of diagnosis, testing and treatment. This review provides an overview of our understanding of equine CDI while also identifying knowledge gaps and the need for a holistic One Health approach to a complicated issue

Genetically related Clostridium difficile from water sources and human CDI cases revealed by whole‐genome sequencing

Clostridium difficile isolates from the environment are closely related to those from humans, indicating a possible environmental transmission route for C. difficile infection (CDI). In this study, C. difficile was isolated from 47.3% (53/112) of lake/pond, 23.0% (14/61) of river, 20.0% (3/15) of estuary and 0.0% (0/89) of seawater samples. The most common toxigenic strain isolated was C. difficile PCR ribotype (RT) 014/020 (10.5%, 8/76). All water isolates were susceptible to fidaxomicin, metronidazole, rifaximin, amoxicillin/clavulanic acid, moxifloxacin and tetracycline. Resistance to vancomycin, clindamycin, erythromycin and meropenem was detected in 5.3% (4/76), 26.3% (20/76), 1.3% (1/76) and 6.6% (5/76) of isolates, respectively. High-resolution core-genome analysis was performed on RT 014/020 isolates of water origin and 26 clinical RT 014/020 isolates from the same year and geographical location. Notably, both human and water strains were intermixed across three sequence types (STs), 2, 13 and 49. Six closely related groups with ≤10 core-genome single nucleotide polymorphisms were identified, five of which comprised human and water strains. Overall, 19.2% (5/26) of human strains shared a recent genomic relationship with one or more water strains. This study supports the growing hypothesis that environmental contamination by C. difficile plays a role in CDI transmission

Whole‐genome sequencing links Clostridium ( Clostridioides ) difficile in a single hospital to diverse environmental sources in the community

Aims To investigate if Clostridium (Clostridioides) difficile infection (CDI), traditionally thought of as hospital-acquired, can be genomically linked to hospital or community environmental sources, and to define possible importation routes from the community to the hospital. Methods and Results In 2019, C. difficile was isolated from 89/300 (29.7%) floor and 96/300 (32.0%) shoe sole samples at a tertiary hospital in Western Australia. Non-toxigenic C. difficile ribotype (RT) 010 predominated among floor (96.6%) and shoe sole (73.2%) isolates, while toxigenic RT 014/020 was most prevalent among contemporaneous clinical cases (33.0%) at the hospital. Whole-genome sequencing and high-resolution core genome single nucleotide polymorphism (cgSNP) analysis on C. difficile strains from hospital and community sources showed no clinical C. difficile RT 014/020 strains were genetically related, and evidence of frequent long-distance, multi-directional spread between humans, animals and the environment. In addition, cgSNP analysis of environmental RT 010 strains suggested transportation of C. difficile via shoe soles. Conclusions While C. difficile RT 014/020 appears to spread via routes outside the healthcare system, RT 010 displayed a pattern of possible importation from the community into the hospital. Significance and Impact of Study These findings suggest developing community-based infection prevention and control strategies could significantly lower rates of CDI in the hospital setting