Survival of bovine-associated serotypes of in bedding sand.

Cattle persistently infected with bovine-adapted serotypes of are an important animal health and food safety issue. One possible mechanism by which infection is sustained in a dairy herd is by survival of in sand used as bedding material. In this study we assessed the survival of 10 to 10 cfu bovine-associated serotypes of (sv. Cerro, Dublin, and Heidelberg) in sterile sand, recycled bedding sand, and gray water collected from a Wisconsin dairy farm. All 3 serotypes persisted at relatively high numbers (>10 cfu/g) for at least 28 d in sterile sand, with sv. Dublin decreasing less than 1 log over 70 d. To our surprise, when low numbers of sv. Dublin (10 cfu) were inoculated into sterile sand, the organism multiplied within 3 d to approximately 10 cfu/g sand and persisted at that level for 28 d. When we inoculated sv. Dublin into recycled bedding sand or sand taken directly from cow pens, we observed a significant decrease in colony-forming units by d 7. In contrast, we observed a significant increase in colony-forming units when sv. Dublin was inoculated into gray water from the sand recycling system. These data demonstrate that can persist for extended periods of time in bedding sand, although this is limited to some extent by the native microbiota in recycled bedding sand.