One Health is a perspective that recognises the interconnectivity of all living systems on our planet, and that the health of humans, animals and the environment are inextricably linked. An example of this involves bacterium Clostridium difficile. C. difficile colonises neonatal gastrointestinal tracts of animals, including humans. However, C. difficile does not compete well with other bacteria and its prevalence diminishes as they start to colonise the gut. The use of antibiotics in humans and food animals eradicates most of the competition in a gut, allowing C. difficile to colonise and multiply to cause disease. Genetically-related C. difficile have been reported in humans and animals, suggestive of zoonotic transmission, although there was no evidence of contact between the two species.
The aim of this project was to explore the potential sources of C. difficile in the environment with a focus on animal-to-human transmission through contaminated food and/or the environment.
Food and environmental sampling were performed in Western Australia (WA). Toxin profiling and PCR ribotyping were used to characterise the isolated C. difficile strains (n = 274). To determine the relatedness of human, animal, food and environmental C. difficile, whole-genome sequencing (WGS) was performed.
C. difficile was isolated from 12.6% (40/317) and 52.0% (204/392) of food and environment samples, respectively. Nearly half (46.3%) were capable of producing toxins. Many of the isolated C. difficile ribotypes were common among humans and food animals. WGS analysis revealed clusters of human and food/environmental isolates, suggesting a very recent shared ancestry. These studies suggest foodborne and environmental transmission of C. difficile in WA. This is likely due to agricultural recycling of human biosolids and/or animal manure resulting in C. difficile contamination of vegetables and the environment.
To reduce the overall burden of C. difficile infection, a “One Health” approach is needed where clinicians, veterinarians, industry partners and government bodies work together for the health of humans, animals and the environment.