Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 21, 2012
Publication Date: February 1, 2013
Repository URL: http://handle.nal.usda.gov/10113/56092
Citation: Kalchayanand, N., Arthur, T.M., Bosilevac, J.M., Harhay, D.M., Shackelford, S.D., Wells, J., Wheeler, T.L., Koohmaraie, M. 2013. Isolation and characterization of Clostridium difficile associated with beef cattle and commercially produced ground beef. Journal of Food Protection. 76(2):256-264. Interpretive Summary: A speculation of Clostridium difficile-associated disease from a consumption of contaminated meat products has been raised. The strains NAP-1 and NAP-7 have been recently isolated from Canadian calves and retail ground meat products in Canada and the United States. However, information on the prevalence of C. difficile associated with beef cattle during processing and in commercially produced ground beef is very limited. In this study, carcass samples from 5 different plants were taken and tracked at various steps during processing and commercially produced ground beef samples were obtained from across the U.S. The results showed that low prevalence of C. difficile was found on cattle hides. There was no C. difficile found on pre-evisceration carcasses, post-intervention carcasses, or in commercially produced ground beef, indicating that the interventions used throughout the processing plants are effective and prevent contamination of the carcasses from C. difficile. The C. difficile isolates were characterized both phenotypically and genotypically and compared to reference strains. None of the isolates were identified as strains NAP-1 or NAP-7. Most of the isolates were sensitive to antibiotics commonly used in human therapy. The results of our study indicate that the U.S. beef supply has a low risk associated with this emerging pathogen.
Technical Abstract: The incidence of Clostridium difficile infection has recently increased in North American and European countries. This pathogen has been isolated from retail pork, turkey, and beef products and reported associated with human illness. This increase in infections has been attributed to the emergence of a toxigenic strain designated North America pulsed-field gel electrophoresis type 1 (NAP1). The NAP1 strain has been isolated from calves as well as ground meat products, leading to speculation of illness from consumption of contaminated meat products. However,information on C. difficile associated with beef cattle during processing and commercially produced ground beef is limited. To address this data gap, samples from various steps during beef production were collected. Samples from hides (n = 525),preevisceration carcasses (n = 475), postintervention carcasses (n=471), and 956 commercial ground beef samples were collected from across the United States. The prevalence of C. difficile spores on hides was 3.2%. C. difficile spores were not detected on preevisceration and postintervention carcasses or in commercially produced ground beef. Phenotypic and genetic characterizations were carried out for all 18 isolates collected from hide samples. Twenty-two percent of the isolates were nontoxigenic strains, while 78% of the isolates were toxigenic. Toxinotyping and PCR ribotyping patterns revealed that 6 and 33% of the isolates were identified as NAP1 and NAP7 strains, respectively. This article evidences that the prevalence of C. difficile, specifically pathogenic strains, in the U.S. beef production chain is low.