Clostridium (Clostridioides) difficile is a ubiquitous spore-forming Gram-positive bacillus causing life-threatening, toxin-mediated diarrhoea. The incidence of C. difficile infection (CDI) in Australia has steadily increased since mandatory reporting commenced in 2010, and annual costs to the Australian healthcare system currently amount to >$100 million. While a long-standing notion that CDI is a hospital-acquired infection prevails, increasing evidence from investigation of community sources/reservoirs and whole genome sequencing suggests that most CDI cases in Australia are likely acquired within the community. Indeed, 76% of all CDI cases identified in Australia are community-onset. Current surveillance focuses on hospital-identified infections and does not adequately capture the true extent of C. difficile transmission in the community, resulting in under-estimation of the One Health significance of CDI.
A substantial increase in CDI cases has occurred across Australia since late 2021, attributed to several emerging strains and an intriguing resurgence of C. difficile ribotype (RT) 244, which previously caused a community-based outbreak of severe CDI in 2011/12. The source of these emerging and resurgent strains has not yet been identified. Our group has identified significant C. difficile reservoirs in livestock, wild and domestic animals, and contamination of wastewater, retail vegetables, gardening products and public parks and home gardens with animal manure may be important for transmission. Many of these community sources/reservoirs harbour C. difficile RT 014, the most common strain causing 25-30% of human CDI in Australia, demonstrating the huge role environmental sources play in transmission of C. difficile here.
CDI continues to increase in incidence in Australia and emerging strains have the potential to cause more severe disease and an even heavier burden on the healthcare system. Current control measures focus on hospital-based infection prevention and control and fail to prevent disease acquired within the community. A One Health approach, including better-informed management of C. difficile in agriculture, horticulture and wastewater treatment, and better-informed care of high-risk individuals in the community is required.