Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2001
Publication Date: 10/25/2001
Citation: Zhao, T., Doyle, M.P., Cray, P.J., Zhao, P., Ladely, S.R. 2001. Occurrence of Salmonella enterica Serotype Typhimurium DT104A in Retail Ground Beef. Journal of Food Protection. Vol. 65. No. 2. P. 403-407. Interpretive Summary: Salmonella bacteria are ubiquitous in nature and are associated with food borne disease outbreaks. Some strains of Salmonella cause more illness than others, one in particular is Salmonella Typhimurium DT104. We sampled 404 fresh ground beef samples for the presence of Typhimurium DT104. Fourteen (3.5%) of the samples were positive for Salmonella and of these, five were identified as Typhimurium DT104A, a subtype of DT104 Interestingly, when we conducted tests to determine if the DT104 isolates were susceptible to antimicrobials, all five were resistant to ampicillin, streptomycin, sulfamethoxazole and tetracycline but sensitive to chloramphenicol. Typically DT104 is resistant to all five antimicrobials. These data indicate that Salmonella Typhimurium DT104 can be recovered from ground meat but that those found among our samples are a variant of typical DT104 isolates. Further, these data are important as the industry develops measures to control Salmonella in the food supply.
Technical Abstract: Surveillance data of cattle and human isolates of Salmonella enterica serovar typhimurium DT104 indicate that this pathogen emerged worldwide in the 1980's, particularly in cattle. Studies were conducted to determine the prevalence of Salmonella Typhimurium DT104 in ground beef. A total of 404 fresh ground beef samples obtained at retail stores from New York, San Francisco, Philadelphia, Denver, Atlanta, Houston, and Chicago were shipped overnight to Georgia for processing. Salmonella spp. were isolated from 14 (3.5%) samples. Eight different serotypes were identified among the isolates, including Salmonella Typhimurium (5), Salmonella Lille (3), Salmonella Montevideo (1), Salmonella Hadar (1), Salmonella Meleagridis (1), Salmonella Cero (1), Salmonella Kentucky (1), and Salmonella Muenster (1). Antibiotic-resistance profiles indicated that all five Salmonella Typhimurium isolates were resistance to ampicillin, streotomycin, sulfamethoxazole, ticarcillin, and tetracyclin but that they were sensitive to chloramphenicol. Phage typing showed that all five Salmonella Typhimurium isolates were DT104A, a subtype of DT104. All five Salmonella Typhimurium DT104A isolates were obtained from ground beef sampled from retail outlets in San Francisco. Pulsed-field gel electrophoresis (PFGE) genomic DNA profiles of the five Salmonella Typhimurium DT104A isolates from ground beef were identical to those of four control Salmonella Typhimurium DT104 penta-resistance isolates from cattle that were used for comparison. These data indicate that Salmonella Typhimurium DT104A can be isolated from retail ground beef.