Occurrence of Antimicrobial-Resistant Escherichia coli and Salmonella enterica in the Beef Cattle Production and Processing Continuum

Authors

John W. Schmidt, USDA-ARSFollow
Getahun E. Agga, USDA-ARSFollow
Joseph M. Bosilevac, USDA Meat Animal Research CenterFollow
Dayna M. Brichta-Harhay, USDA-ARSFollow
Steven D. Shackelford, USDA-ARS
Rong Wang, USDA-ARSFollow
Tommy L. Wheeler, USDA-ARSFollow
Terrance M. Arthur, USDA Meat Animal Research CenterFollow

Date of this Version

2015

Document Type

Article

Citation

Schmidt JW, Agga GE, Bosilevac JM, Brichta-Harhay DM, Shackelford SD, Wang R, Wheeler TL, Arthur TM. 2015. Occurrence of antimicrobial-resistant Escherichia coli and Salmonella enterica in the beef cattle production and processing continuum. Appl Environ Microbiol 81:713–725.

Comments

U.S. Government Work

Abstract

Specific concerns have been raised that third-generation cephalosporin-resistant (3GC^r) Escherichia coli, trimethoprim-sulfamethoxazole- resistant (COT^r) E. coli, 3GC^r Salmonella enterica, and nalidixic acid-resistant (NAL^r) 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 in feces and hides (at feedlot and processing plant), pre-evisceration carcasses, and final carcasses from three lots of fed cattle (n=184). The prevalences and concentrations were further determined for strip loins from 103 of the carcasses. 3GC^r Salmonella was detected on 7.6% of hides during processing and was not detected on the final carcasses or strip loins. NAL^r S. enterica was detected on only one hide. 3GC^r E. coli and COT^r E. coli were detected on 100.0% of hides during processing. Concentrations of 3GC^r E. coli and COT^r E. coli on hides were correlated with pre-evisceration carcass contamination. 3GC^r E. coli and COT^r E. coli were each detected on only 0.5% of final carcasses and were not detected on strip loins. Five hundred and 42 isolates were screened for extraintestinal pathogenic E. coli (ExPEC) virulence-associated markers. Only two COT^r E. coli isolates from hides were ExPEC, indicating that fed cattle products are not a significant source of ExPEC causing human urinary tract infections. The very low prevalences of these organisms on final carcasses and their absence on strip loins demonstrate that current sanitary dressing procedures and processing interventions are effective against antimicrobial-resistant bacteria.