Geographical variation in ribotype profiles of Escherichia coli isolated from humans, swine, poultry, beef, and dairy cattle in Florida

Waters impacted by fecal pollution can exact high risks to human health and can result in financial losses due to closures of water systems used for recreation and for harvesting seafood. Identifying the sources of fecal pollution in water is paramount in assessing the potential human health risks involved as well as in assessing necessary remedial action. Recently, various researchers have used the ribotyping method to identify sources of bacterial indicators (Escherichia coli and enterococci) in environmental waters. While these studies have identified genotypic differences between human- and animal-derived indicators that are capable of differentiating organisms isolated from humans and various animal hosts, most have focused on organisms collected from a confined geographic area and have not addressed the question of whether these ribotype profiles are watershed specific or if they can be applied universally to organisms from other geographic locations. In this study, E. coli isolates were obtained from humans, beef cattle, dairy cattle, swine, and poultry from locations in northern, central, and southern Florida and were subjected to ribotyping analysis. The intent was to determine (i) if ribotype profiles are capable of discriminating the source of E. coli at the host species level and (ii) if the resulting fingerprints are uniform over an extended geographic area or if they can be applied only to a specific watershed. Our research indicated that, using a single restriction enzyme (HindIII), the ribotyping procedure is not capable of differentiating E. coli isolates from the different animal species sampled in this study. Results indicate, however, that this procedure can still be used effectively to differentiate E. coli as being either human or animal derived when applied to organisms isolated from a large geographic region.