Prevalence of molecular markers for Salmonella and Shiga toxigenic Escherichia coli (STEC) in whole-muscle beef cuts sold at retail markets in Costa Rica

The present study sought to determine the prevalence of molecular markers for Salmonella and Shiga toxigenic Escherichia coli (STEC) serogroups O26, O45, O103, O111, O121, O145, and O157 in whole-muscle beef cuts sold at retail in urban and semi-rural areas of Costa Rica. A total of 279 (171 urban, 108 semi-rural) samples were purchased from 93 butcher shops between August of 2012 and August of 2013 and tested for the presence of molecular markers characteristic of Salmonella and STEC using the DuPont Qualicon BAX^® System. The overall prevalence of Salmonella and STEC markers was 3.6% (10/279) and 4.7% (13/279), respectively. Salmonella markers were more frequently found in semi-rural (6.5%; 7/108) than in urban (1.8%; 3/171) areas. Similarly, STEC markers were more commonly detected in semi-rural (7.4%; 8/108) than in urban (2.9%; 5/171) areas. A marginal association was found between Salmonella markers and sampling location (P = 0.0496), whereas the presence of STEC markers and sampling location were considered independent (P = 0.1416). Among the 13 positive samples for STEC, 38 O-antigen gene fragments were amplified, with serogroups O45 and O121 being the predominant (28.9 and 21.1%, respectively). Markers for somatic antigens O111 and O157 were not detected in any of the samples. The present investigation is the first of its kind in Central America and shows that both Salmonella and STEC may be commonly present in whole-muscle raw beef cuts sold at retail markets in Costa Rica. Consequently, consumers may be directly at risk of foodborne illness due if meat products are not adequately cooked and handled in food service or domestic settings. Future work should emphasize continuous monitoring of the presence of these and other zoonotic pathogens in meat and meat products and on the implementation and validation of adequate food safety controls along the farm-to-table continuum.