Salmonella enterica in South American sea lions (Otaria byronia) from the north coast of San Matias Gulf (Patagonia, Argentina)

Javier Aníbal Origlia , Gustavo Daneri, Fabiana Moredo, Ariel Rogé, Esperanza Varela, Gabriela Giacoboni 

There is little information about the diseases that can affect the Argentine populations of pinnipeds. Salmonellosis has been described in marine mammals of different regions of the world. The aim of this study was to detect the presence of Salmonella enterica in pinnipeds that inhabit the marine littoral zone of Río Negro province (Argentina) during the breeding season, the serovars circulation and the antimicrobial susceptibility. In December 2017 and March 2018, faecal samples (n=201) were collected from Otaria byronia in three rookeries located on the north coast of the San Matías Gulf (Punta Bermeja n= 79, Promontorio Belen n= 89 and Caleta de los Loros n=33). Samples were taken with swabs and were kept in Cary Blair transport medium. The isolation was carried out using the traditional bacteriological method (FDA-BAM). Presumptive Salmonella colonies were confirmed by biochemical tests. Isolates identified as Salmonella enterica were serotyped by agglutination according to White-Kauffmann-Le Minor scheme.  Nine antimicrobials were tested (ampicillin, nalidixic acid, gentamicin, ciprofloxacin, chloramphenicol, tetracycline, trimethoprim-sulfamethoxazole, colistin and fosfomycin) by disk diffusion method according Clinical and Laboratory Standards Institute guidelines. From a total of 201 samples, 14 (7%) Salmonella strains were isolated. Three serovars of S. enterica were found: S. Newport 11 (79%) S. Cerro 2 (14%) and S. Enteritidis 1 (7%). Strains were susceptible to all the antimicrobial agents tested. Several Salmonella serovars from a variety of pinniped species were described before. S. Newport and S. Cerro were previously found in Phocarctos hookeri from New Zealand and in Otaria byronia from Chile. Although all serovars can cause disease in humans, S. Enteritidis is one of the most important serovars of Salmonella transmitted from animals to humans. This is the first report about S. Enteritidis in pinnipeds from South America coasts. This finding warns about new zoonotic agents in these wildlife species.

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