High prevalence of Clostridium difficile on retail root vegetables, Western Australia

Aims: The incidence of community-associated Clostridium difficile infection (CA-CDI) in Australia has increased since mid-2011. With reports of clinically important C. difficile strains being isolated from retail foods in Europe and North America, a foodborne source of C. difficile in cases of CA-CDI is a possibility. This study represents the first to investigate the prevalence and genotypes of C. difficile in Australian retail vegetables. Methods and Results: A total of 300 root vegetables grown in Western Australia (WA) were collected from retail stores and farmers’ markets. Three vegetables of the same kind bought from the same store/market were treated as one sample. Selective enrichment culture, toxin profiling and PCR ribotyping were performed. Clostridium difficile was isolated from 30% (30/100) of pooled vegetable samples, 55·6% of organic potatoes, 50% of nonorganic potatoes, 22·2% of organic beetroots, 5·6% of organic onions and 5·3% of organic carrots. Over half (51·2%, 22/43) the isolates were toxigenic. Many of the ribotypes of C. difficile isolated were common among human and Australian animals. Conclusions: Clostridium difficile could be found commonly on retail root vegetables of WA. This may be potential sources for CA-CDI. Significance and Impact of the Study: This study enhances knowledge of possible sources of C. difficile in the Australian community, outside the hospital setting.