Potentially Zoonotic Bacteria in Exotic Freshwater Turtles from the Canary Islands (Spain)

The pond slider (Trachemys scripta) is native to the southeastern United States but has been introduced all around the world, including to the Canary Islands (Spain), along with other less-common exotic freshwater turtles such as Graptemys pseudogeographica, Mauremys spp., and Pseudemys peninsularis. The aim of this study was to determine the presence of pathogenic bacteria in these animals and to evaluate the associated health risks for humans and local fauna. For this purpose, cloacal samples from 42 specimens collected on the islands of Tenerife and Gran Canaria (Canary Islands) were analyzed for potentially zoonotic bacteria using selective culture media and PCR. Non-tuberculous mycobacteria were the most isolated pathogen (57.9%), followed by Yersinia enterocolitica (42.1%) and Escherichia coli carrying stx and/or eae genes (33.3%). Salmonella spp. was detected in 31.0% of the chelonians, identifying Salmonella Typhi and Salmonella Typhimurium serotypes. Staphylococcus spp. showed a prevalence of 21%, mainly Staphylococcus aureus along with one antibiotic-resistant Staphylococcus hominis isolate. Pseudomonas spp. were found in 10.1% of samples, although only one isolate corresponded to Pseudomonas aeruginosa. Campylobacter spp. and Vibrio spp. were detected at low frequencies (<10%), and Listeria monocytogenes was not identified. Overall, the results indicate that aquatic turtle populations in the Canary Islands pose notable health risks, especially for animal handlers and people with compromised immune systems.