Detection of salmonellae in different turtle species within a headwater spring ecosystem

Sediments and water from the slough arm of Spring Lake, the headwaters of the San Marcos River, Texas, USA, as well as swabs from biofilms on carapaces and from the cloacae of 18 common musk turtles (Sternotherus odoratus), 21 red-eared sliders (Trachemys scripta elegans), nine Texas river cooters (Pseudemys texana), one snapping turtle (Chelydra serpentina serpentina), and three Guadalupe spiny soft-shell turtles (Apalone spinifera guadalupensis), caught at the same site, were analyzed for salmonellae by culture and molecular techniques. Although enrichment cultures from sediment and water samples were negative for salmonellae in polymerase chain reaction (PCR)-based analyses, this technique detected salmonellae in the enrichments from both carapaces and cloacae of 11 musk turtles (61%), eight red-eared sliders (38%), and the snapping turtle. Salmonellae could also be detected in the enrichments from the carapaces of two additional red-eared sliders and two Texas river cooters; the remaining samples were negative. Further characterization of isolates obtained from the enrichment cultures of seven selected individuals that represented all turtle species with salmonellae confirmed the presence of Salmonella enterica subspecies enterica, with serovars Rubislaw, Newport, Gaminara, and Thompson identified. These results demonstrate the presence of different strains of potentially human pathogenic salmonellae naturally occurring on several turtle species with different life histories even within supposedly pristine environments.