Salmonella enterica in Pinnipeds, Chile

To the Editor: Several wildlife-associated zoonotic agents have played a major role in the emergence of diseases in humans (1). However, diseases can also emerge in wildlife as a result of human activities, such as contamination of the marine environment and its fauna by the disposal of nontreated human sewage. Salmonella enterica is among the agents identified as causing infection in various marine birds and mammals, including pinnipeds, from different geographic regions (2–4).
The objective of our study was to determine whether S. enterica infection occurs in pinnipeds from the Chilean coast. During August–December 2010, we obtained samples from 13 South American sea lions (Otaria flavescens) that the sanitary authority found malnourished and stranded at the northern Chilean beaches of Antofagasta (23°40′S; 70°24′W) and Los Vilos (31°54′S; 71°30′W) (Table). The pinnipeds showed no clinical signs or symptoms of disease; however, rectal swab samples were obtained during their stay for rehabilitation at the Buin Marino facilities (Santiago, Chile). After the animals recovered, they were released to their original habitat.

The swab samples were placed in Cary-Blair transport medium (COPAN, Murrieta, CA, USA) for shipment to the laboratory (Laboratory of Infectious Diseases, University of Chile, Santiago). To isolate bacteria, we placed the swab samples into 5 mL of buffered peptone water (Difco APT broth; Becton Dickinson, Franklin Lakes, NJ, USA), incubated them for 24 h at 42°C with agitation, and then aliquots of the suspension were transferred into the following media: modified semisolid Rappaport-Vassiliadis basal medium (Oxoid, São Paulo, Brazil) with novobiocin (20 µg/mL), selenite cysteine broth base (Oxoid), and xylose lysine desoxycholate agar (Difco XLD; Becton Dickinson). After the aliquots were incubated at 37°C for 24–48 h, we identified suspected colonies by using biochemical tests and invA gene detection by PCR (5). Results showed that 2 of the 13 animals were infected with S. enterica strains, which were serotyped as S. enterica serotype Newport and S. enterica serotype Havana (Table), according to the Kauffmann-White scheme (6). Testing showed that the strains were susceptible to the following antimicrobial drugs: ampicillin, chloramphenicol, tetracycline, amoxicillin/clavulanic acid, trimethoprim/sulfamethoxazole, cefotaxime, nalidixic acid, nitrofurantoin, ciprofloxacin, ceftazidime, and cefoxitin (7).
Our results confirm S. enterica infection in pinnipeds from Chile and, more broadly, the South American coast and contrast with previous unsuccessful attempts to detect Salmonella spp. in pinnipeds from Valdivia, 2,200 km to the south (8). This finding suggests geographic variability in the epidemiology of infection; however, this possibility must be confirmed in additional studies with more samples and additional regions.
S. enterica is an endemic bacterium in Chile that causes infection in humans and domestic animals. The Chilean sanitary authority includes S. enterica infection among the list of notifiable diseases, but surveillance is not conducted for S. enterica in wildlife. However, consideration should be given to changing this situation, given a report suggesting S. enterica as a priority for active surveillance (9). In addition, S. enterica serotypes Newport and Havana have been detected in Chile’s human population (10), strengthening the necessity for official support for initiatives addressing the need to elucidate the epidemiology of Salmonella in aquatic animals.

Natalie Sturm, Pedro Abalos, Alda Fernandez, Guillermo Rodriguez, Pilar Oviedo, Viviana Arroyo, and Patricio Retamal

Author affiliations: Universidad de Chile, Santiago, Chile (N. Sturm, P. Abalos, P. Oviedo, V. Arroyo, P. Retamal); Instituto de Salud Pública, Santiago (A. Fernandez); Buin Marino, Santiago (G. Rodriguez)

Acknowledgment

This work was supported by a grant from the International Society for Infectious Diseases.

References

Jones KE, Patel NG, Levy MA, Storeygard A, Balk D, Gittleman JL, Global trends in emerging infectious diseases. Nature. 2008;451:990–3. DOIPubMed
Fenwick SG, Duignan PJ, Nicol CM, Leyland MJ, Hunter JE. A comparison of Salmonella serotypes isolated from New Zealand sea lions and feral pigs on the Auckland Islands by pulsed-field gel electrophoresis. J Wildl Dis. 2004;40:566–70.PubMed
Stoddard RA. Salmonella and Campylobacter spp. in northern elephant seals, California. Emerg Infect Dis. 2005;11:1967–9.
Palmgren H, McCafferty D, Aspan A, Broman T, Sellin M, Wollin R, Salmonella in sub-Antarctica: low heterogeneity in Salmonella serotypes in South Georgian seals and birds. Epidemiol Infect. 2000;125:257–62. DOIPubMed
Malorny B, Hoorfar J, Bunge C, Helmuth R. Multicenter validation of the analytical accuracy of Salmonella PCR: towards an international standard. Appl Environ Microbiol. 2003;69:290–6. DOIPubMed
Grimont PAD, Weill FX. Antigenic formulae of the Salmonella serovars. 9th ed. WHO Collaborating Center for Reference and Research on Salmonella, Institut Pasteur; 2007 [cited 2011 Sep 23]. http://www.pasteur.fr/ip/portal/action/WebdriveActionEvent/oid/01s-000036-089
Clinical Laboratory Standards Institute. Performance standards for antimicrobial susceptibility testing; twentieth informational supplement. M100–S20, vol. 30, no. 1; 2010 [cited 2011 Sep 23]. http://www.clsi.org/source/orders/free/m100-s20.pdf
González-Fuentes M, Latif F, Fernández F, Villanueva MP, Ulloa J, Fernández H. Species of the family Enterobacteriaceae in feces of South American sea lion, Otaria flavescens, settled in the Valdivia River [in Spanish]. Revista de Biología Marina y Oceanografía. 2010;45:331–4.
Tavernier P, Dewulf J, Roelandt S, Roels S. Wildtool, a flexible, first-line risk assessment system for wildlife-borne pathogens. Eur J Wildl Res. 2011;57:1065–75. DOI
Hendriksen RS, Vieira AR, Karlsmose S, Lo Fo Wong DMA, Jensen AB, Wegener HC, Global monitoring of Salmonella serovar distribution from the World Health Organization Global Foodborne Infections Network country data bank: results of quality assured laboratories from 2001 to 2007. Foodborne Pathog Dis. 2011;8:887–900. DOIPubMed

Table

Table. Characteristics of South American sea lions (Otaria flavescens) tested for infection with Salmonella spp., Chilean coast, August–December 2010

Suggested citation for this article: Sturm N, Abalos P, Fernandez A, Rodriguez G, Oviedo P, Arroyo V, et al. Salmonella enterica in pinnipeds, Chile [letter]. Emerg Infect Dis [serial on the Internet]. 2011 Dec [date cited]. http://dx.doi.org/10.3201/eid1712.111103