Prevalence and Genotypic Characteristics of Clostridium difficile in a Closed and Integrated Human and Swine Population

Recently, an apparent rise in the number of cases attributed to community-acquiredClostridium difficile infection has led researchers to explore additional sources of infection. The finding ofC. difficile in food animals and retail meat has raised concern about potential food-borne and occupational exposures. The objective of this study was to compareC. difficile isolated from a closed population of healthy individuals consisting of both humans and swine in order to investigate possible food safety and occupational risks for exposure. Using a multistep enrichment isolation technique, we identified 11.8% of the human wastewater samples and 8.6% of the swine samples that were positive forC. difficile . The prevalences ofC. difficile in swine production groups differed significantly (P < 0.05); however, the prevalences in the two human occupational group cohorts did not differ significantly (P = 0.81). The majority of the human and swine isolates were similar based on multiple typing methods. The similarity inC. difficile prevalence in the human group cohorts suggests a low occupational hazard, while a greatly decreased prevalence ofC. difficile in later-stage swine production groups suggests a diminished risk for food-borne exposure. The similarity of strains in the two host species suggests the possibility of a common environmental source for healthy individuals in a community setting.