Skip to main content
ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety & Quality Research » Research » Publications at this Location » Publication #310058

Research Project: PATHOGEN MITIGATION IN LIVESTOCK AND RED MEAT PRODUCTION

Location: Meat Safety & Quality Research

Title: Occurrence of antimicrobial-resistant Escherichia coli and Salmonella enterica in the beef cattle production and processing continuum

Author
item Schmidt, John
item Agga, Getahun
item Bosilevac, Joseph - Mick
item Harhay, Dayna
item Shackelford, Steven
item Wang, Rong
item Wheeler, Tommy
item Arthur, Terrance

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/6/2014
Publication Date: 1/5/2015
Publication URL: http://handle.nal.usda.gov/10113/60659
Citation: Schmidt, J.W., Agga, G.E., Bosilevac, J.M., Harhay, D.M., Shackelford, S.D., Wang, R., Wheeler, T.L., Arthur, T.M. 2015. Occurrence of antimicrobial-resistant Escherichia coli and Salmonella enterica in the beef cattle production and processing continuum. Applied and Environmental Microbiology. 81(2):713-725.

Interpretive Summary: Specific concerns have been raised that E. coli and Salmonella resistant to antimicrobials critically important to human medicine are present in beef cattle feeding operations, may survive processing, contaminate final products and adversely affect human health. Beef cattle were sampled at seven points from farms through final products to determine the occurrences and concentrations of these resistant bacteria. Antimicrobial-resistant E. coli were present on 100% of hides both at feedlots and when cattle begin processing. Antimicrobial-resistant Salmonella were found on 11% of hides at feedlots and on 8% of hides when cattle begin processing. Antimicrobial resistant E. coli were present on 1% of final carcasses but were not found on final products. Antimicrobial-resistant Salmonella were not found on carcasses or final products. These results indicate that sanitizing interventions currently employed at beef processing plants are effective against antimicrobial resistant bacteria, and that beef products are not a significant source of antimicrobial resistance foodborne pathogens.

Technical Abstract: Specific concerns have been raised that 3rd-generation cephalosporin-resistant (3GCr) Escherichia coli, trimethoprim-sulfamethoxazole-resistant (COTr) E. coli, 3GCr Salmonella enterica, and nalidixic acid-resistant (NALr) S. enterica, may be present in cattle production environments, persist through beef processing, and contaminate final products. The prevalences and concentrations of these organisms were determined for 184 fed cattle from three lots at the following locations: feces and hides (at feedlot and processing plant), pre-evisceration carcasses, and final carcasses. Prevalences were determined for strip loin steaks from 103 of those carcasses. 3GCr Salmonella were detected on 7.6 % of hides during processing and were not detected on final carcasses or strip loins. NALr S. enterica was detected on only one hide. 3GCr E. coli and COTr E. coli were detected on 100.0 % of hides during processing. Concentrations of 3GCr E. coli and COTr E. coli on hides were correlated to pre-evisceration carcass contamination. 3GCr E. coli and COTr E. coli were each detected on only 0.5 % of final carcasses and were not detected on strip loins. Five hundred and forty-two isolates were screened for extraintestinal pathogenic E. coli (ExPEC) virulence-associated markers. Only two COTr E. coli isolated from hides were ExPEC, indicating that fed cattle products are not a significant source of ExPEC causing human urinary tract disease. The very low prevalences of these organisms on final carcasses, and their absence on strip loins demonstrate that currently employed sanitary processing interventions are effective against antimicrobial-resistant bacteria.