A farm-to-fork quantitative microbial exposure assessment of beta-lactam resistant Escherichia coli among U.S. beef consumers

Authors: ZHANG, YANGJUNNA - University Of Nebraska; Schmidt, John; Arthur, Terrance; Wheeler, Tommy; ZHANG, QI - University Of Nebraska; WANG, BING - University Of Nebraska

Submitted to: Microorganisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2022
Publication Date: 3/19/2022
Citation: Zhang, Y., Schmidt, J.W., Arthur, T.M., Wheeler, T.L., Zhang, Q., Wang, B. 2022. A farm-to-fork quantitative microbial exposure assessment of beta-lactam resistant Escherichia coli among U.S. beef consumers. Microorganisms. 10(3). Article 661. https://doi.org/10.3390/microorganisms10030661.
DOI: https://doi.org/10.3390/microorganisms10030661

Interpretive Summary: A quantitative microbial exposure assessment (QMEA) model is a tool that can be used to assess the impact of antibiotic use during cattle production on consumer exposure to antibiotic resistant bacteria via beef. Foodborne pathogens resistant to the antibiotics used to cure human infections are so infrequently found in the United States beef production and processing chain that QMEA models cannot be constructed unless an alternative data source is used. Thus, a QMEA model was established using non-pathogenic beta-lactam-resistant Escherichia coli as sentinels of antimicrobial resistance since they provide adequate data for risk model development. The model evaluated the relative contribution of antimicrobial use during beef cattle production, as well as other factors associated with the beef production and processing chain, to human exposures to antibiotic resistant E. coli at the time of consumption. The model found that antibiotic use had an extremely minor impact on consumer exposure to beta-lactam resistant E. coli. The model revealed that several other factors, including processing interventions, consumer hygienic practices and proper cooking, had much larger impacts on consumer exposure to beta-lactam resistant E. coli. This model suggests that further restrictions on antimicrobial use in cattle are unlikely to result in meaningful reductions of human exposures to antibiotic resistant bacteria through United States beef consumption.

Technical Abstract: A quantitative microbial exposure assessment model was established to provide an estimate of consumer exposure to ß-lactam resistant Escherichia coli (BR-EC) by consumption of beef products without a claim regarding antimicrobial use (termed “conventional”, CONV) and beef products with a “raised without antimicrobials (RWA)” claim. The model simulated the fate of BR-EC along the beef supply chain and compared the per-serving exposure from consumption of intact beef cuts, non-intact beef cuts, and ground beef. Additionally, this study investigated the relative contribution of antimicrobial use during beef cattle production, as well as other factors associated with beef processing and post-processing operations, to human exposures at the time of consumption. The model predicted mean number of BR-EC was 4.7×10-5, 1.7×10-4 and 2.8×10-1 CFU/serving for intact beef cuts, non-intact cuts, and ground beef at the time of consumption, respectively. Simulated results showed that a change in antimicrobial use among beef cattle from baseline to “no use in animals” may be associated with reduced exposure to BR-EC through beef consumption, but the absolute reduction is limited (3.9×10-5, 1.4×10-4 and 2.4×10-1 CFU/serving of intact, nonintact beef cuts and ground beef). Sensitivity analyses suggested that factors related to sectors along the supply chain, i.e., feedlots, abattoirs, retailers, and consumers, were all important regarding human exposure to BR-EC, but the BR-EC contamination in animal feces as the initial model inputs and cooking temperature were the most critical factors to controlling BR-EC on intact/non-intact beef cuts and ground beef, respectively. The model estimates indicated that the efficacy of restrictions on cattle antimicrobial use in mitigating human exposure to BR-EC through beef consumption pathway is questionable. Compared to antimicrobial use restrictions, an integration of good cooking and hygienic practices at home and advanced safety management practices in beef processing and post-processing continuum play more critical roles in reducing human exposure to antimicrobial resistant bacteria in beef products.