Prevalence, Serotype Diversity, Antimicrobial Resistance, and Risk Factors Associated with Salmonella Detection in Chelonians in Algeria

Background/objectives: Chelonians are recognized as silent carriers of different Salmonella serovars. Despite the public health relevance of these animals, data on the prevalence, serovars, antimicrobial resistance, and influencing epidemiological factors are lacking in Algeria. This study aims to investigate, for the first time, the prevalence and the circulating Salmonella serotypes; to determine the antimicrobial resistance profiles; and to study epidemiological risk factors associated with Salmonella occurrence in Algerian chelonians. Methods: Ninety-three (93) fecal swabs of terrestrial and freshwater turtles in different regions of eastern Algeria were analyzed for Salmonella and tested for phenotypic antimicrobial susceptibility. Results: An overall prevalence of 55.9% (52/93) was detected, with differences depending on the species. Of 52 positive isolates, 51 were serotyped, and all underwent antimicrobial susceptibility testing. The majority of the isolates belonged to Salmonella Langford (15/51, 29.4%), to 4,5,12:b:e,n,x (8/51, 15.7%), and to Salmonella enterica subsp. salamae II (9,12:z29:1,5) (6/51, 11.8%), while serovars Kenya (3/51) and Reubeuss (2/51) were identified for the first time in chelonians. Serovars associated with human infection were also identified in this study. All isolates were sensitive to all antimicrobials tested, except for one (1) isolate (S. Langford) resistant to colistin. In the univariable analysis, animal species, study regions, and sex were significantly (p < 0.05) associated with detection of Salmonella, while region was the only associated factor in the final multivariable model. Conclusions: This study highlights the high prevalence of Salmonella in these animals, indicating a potential health risk for humans. Although only one colistin-resistant Salmonella strain was identified, chelonians may still act as potential reservoirs and disseminators of other antimicrobial-resistant bacteria. This risk can be further exacerbated by the limited recognition of these animals as a source of salmonellosis by the authorities in Algeria.