Single cell analysis of nutrient regulation of Clostridioides (Clostridium) difficile motility.

Regulation of bacterial motility to maximize nutrient acquisition or minimize exposure to harmful substances plays an important role in microbial proliferation and host colonization. The technical difficulties of performing high-resolution live microscopy on anaerobes have hindered mechanistic studies of motility in Clostridioides (formerly Clostridium) difficile. Here, we present a widely applicable protocol for live cell imaging of anaerobic bacteria that has allowed us to characterize C. difficile swimming at the single-cell level. This accessible method for anaerobic live cell microscopy enables inquiry into previously inaccessible aspects of C. difficile physiology and behavior. We present the first report that vegetative C. difficile are capable of regulated motility in the presence of different nutrients. We demonstrate that the epidemic C. difficile strain R20291 exhibits regulated motility in the presence of multiple nutrient sources by modulating its swimming velocity. This is a powerful illustration of the ability of single-cell studies to explain population-wide phenomena such as dispersal through the environment.

E. coli O157 and Salmonella spp. in white-tailed deer and livestock.

Escherichia coli O157 and Salmonella spp. are among the leading causes of food-borne illness in the United Sates and bacteria have been isolated from numerous ruminant animal sources. The objective of this study was to assess the incidence of E. coli O157 and Salmonella spp. in white-tailed deer (Odocoileus virginianus) and livestock simultaneously grazing the same rangeland. Escherichia coli O157 was found in 1.25% of cattle, 1.22% of sheep, and 5.00% of water all from samples taken in September; however, no E. coli O157 was found in other sampled months or any species. Salmonella spp. were found in the highest quantities in deer and sheep, 7.69% and 7.32%, respectively. Salmonella spp. were also found in sampled water troughs, goats, and cattle (5.00%, 3.70%, and 1.25%, respectively). Further research examining pathogen distribution is needed to determine if white-tailed deer are a natural reservoir for these bacteria.