au
Clostridioides difficile is an enteric pathogen of significance for humans and other animals, causing toxin-mediated disease via exotoxins toxins A and B, with some strains also producing an additional binary toxin. There are 500,000 cases of C. difficile infection (CDI) and 30,000 associated deaths yearly in the USA while in Australia 8000 cases and 500 deaths occur annually. The prevalence of community-associated C. difficile infection (CA-CDI) has increased in recent decades, with reports estimating CA-CDI accounts for 33.9% and 33.5% of CDI cases in the USA and Europe, respectively [1]. CA-CDI is more extensive in Australia, where it was reported to comprise 80% of all CDI diagnoses [1]. Given the widespread use of composted products in agriculture, turf farms and home gardening, composted products represent a high-risk potential source of C. difficile in the community [1].
Chisholm et al. investigated the prevalence and molecular characteristics of C. difficile from retail garden products in two Australian states. This involved collecting samples of retail garden products, such as soil conditioners, soil mixes and turf. For the isolation of C. difficile, 10 g of sample was added to 90 mL of brain heart infusion broth supplemented with yeast extract, L-cysteine, taurocholic acid, cycloserine and cefoxitin. The inoculated broth was incubated anaerobically for 7 days at 35 °C inside a Whitley A35 Anaerobic Workstation. PCR ribotyping and PCR toxin gene profiling for the presence of toxin A (tcdA), toxin B (tcdB) and binary toxin (cdtA/cdtB) were conducted using a QIAxcel capillary electrophoresis platform. C. difficile was recovered from 257 of 479 (53.7 %) retail garden products in this study. Prevalence was highest in turf (67.1 %, 53/79), followed by soil mixes (57.1 %, 148/259) and soil conditioners (39.7 %, 56/141). Of the 113 distinct ribotypes identified, the most common were 014/020 and QX 686. Toxigenic ribotypes associated with both human infection and production animals in Australia, including 014/020, 056 and 087, were recovered. This suggests that garden products are a potential source of toxigenic C. difficile in the community, posing risks to both humans and animals [1].
The high prevalence of C. difficile in the products tested in this study, raises significant concerns about the role garden products might play in community transmission of C. difficle. Hopefully, these discoveries will encourage further research and stimulate efforts to enhance the safety of composted products. Anaerobic workstations, such as the Whitley A35, make this type of research much more convenient for microbiologists around the world.
References
1. Chisholm JM, Bell C, Lattin M, Lim SC, Reid SA, Selvey LA, Riley TV. High prevalence of Clostridioides difficile in retail garden products from two Australian states. Anaerobe. 2025 Jul 25:102987.
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