Different zoonotic bacteria, including Salmonella spp., Campylobacter spp., and Vibrio spp., have been described in sea turtle gastro-intestinal tract, serving as a potential source of human infections either by shedding of the pathogens into water bodies, beaches or directly to humans through handling. Outbreaks of salmonellosis have been reported after human interaction with contaminated sand with the source of the bacteria being wildlife, thus supporting the need for a better understanding of the transmission of Salmonella from nonfood sources.1,2
During the 2011 nesting season, Salmonella enterica was detected in 14.7% of nesting leatherback sea turtles in the island of St. Kitts.3 In contrast to these findings, previous studies have reported the incidence of Salmonella in wild turtles to be very low.4-6 The causes of this difference in prevalence are unknown. Geographical location, prey choice, human interaction with animals and environment, and the age of the animals are plausible factors.
The main objective of this project was to estimate the prevalence and persistence of S. enterica in the nesting and foraging populations of sea turtles on St. Kitts and in sand from known nesting beaches. In 2014, cloacal swabs from 14 hawksbill, 9 green, and 9 leatherback sea turtles were collected and analyzed using conventional bacteriological and molecular methods. During the same period, 108 samples of dry and wet sand were collected and analyzed from the main nesting beaches on the island of St. Kitts. Preliminary results suggest a higher prevalence of S. enterica in nesting leatherback sea turtles compared to foraging green and hawksbill sea turtles. Bacteria were detected in 2/9 and in 3/9 leatherback sea turtles using conventional bacteriology and molecular methods, respectively. Only one hawksbill, and no green sea turtles were positive for S. enterica using molecular methods. Similarly, only one isolate was recovered from a dry sand sample from a nesting beach. Repetitive-element palindromic PCR fingerprinting, identified a high degree of similarity between S. enterica isolates recovered from leatherback sea turtles from 2012–2014 (n = 5) and the isolate recovered from sand on 2014 (n = 1). The S. enterica isolates formed two distinct clusters (A and B). The 2014 isolates recovered from leather back sea turtles clustered together, and the sand sample isolate and 3 other S. enterica recovered from leatherback sea turtles during 2012 and 2013 presented identical patterns. Laboratory controlled microcosm studies were performed in water and sand (dry and wet) incubated at 25 or 35°C to determine the persistence of representative strains of genotype A and B in these environments. There was a relationship between temperature and substrate in the persistence of S. enterica. Isolates recovered from sea turtle and sand persisted for at least 32 d in most microcosms, but culturable bacteria significantly decreased after 16 d in dry sand incubated at 35°C. This information provides a better understanding of the epizootiology of S. enterica in marine reptiles in the Caribbean.
* Presenting author
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