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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Meat Safety and Quality » Research » Publications at this Location » Publication #391045
Research Project: Holistic Tactics to Advance the Microbiological Safety and Quality of the Red Meat Continuum

Location: Meat Safety and Quality

Title: Identification of dominant factors contributing to persistence of third-generation cephalosporin-resistant Salmonella at a beef cattle feedyard

Author
item Schmidt, John
item Murray, Sarah
item Dickey, Aaron
item Wheeler, Tommy
item Harhay, Dayna
item Arthur, Terrance

Submitted to: International Association for Food Protection Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2023
Publication Date: 7/31/2023
Citation: Schmidt, J.W., Murray, S.A., Dickey, A.M., Wheeler, T.L., Harhay, D.M., Arthur, T.M. 2023. Identification of dominant factors contributing to persistence of third-generation cephalosporin-resistant Salmonella at a beef cattle feedyard. [Abstract]. International Association for Food Protection Proceedings. T4-10.

Interpretive Summary:

Technical Abstract: Introduction: Beef cattle are suspected to contribute to human 3GC-resistant Salmonella infections. Commensal third-generation cephalosporin (3GC)-resistant Escherichia coli are more frequently isolated than 3GC-resistant Salmonella at beef cattle feedyards and are theorized reservoirs of 3GC resistance. Purpose: The goal of this research was to employ whole genome sequencing (WGS) to determine the contribution of 3GC-resistant E. coli to the occurrence of 3GC-resistant Salmonella at a beef cattle feedyard in Nebraska. Methods: During each of 24 consecutive months 4 samples of pen surface material were obtained from 5 pens (N = 480) at a Nebraska feedyard. Illumina WGS was performed and susceptibilities to 14 antimicrobial agents were determined for 121 3GC-susceptible Salmonella, 121 3GC-resistant Salmonella, and 203 3GC-resistant E. coli isolates. Results: 3GC-susceptible Salmonella isolates were predominantly Muenchen (70.2%) and Montevideo Clade 1 (23.1%). 3GC-resistant Salmonella isolates were predominantly Montevideo Clade 2 (84.3%). One bla gene type (blaCMY-2) and the IncC plasmid replicon were present in 100% and 97.5% of the 3GC-resistant Salmonella, respectively. Conversely, 11 bla gene types distributed were distributed across 42 3GC-resistant E. coli multilocus sequence types. The blaCMY-2 gene and IncC plasmid replicon were present in 37.9% and 9.9% of the 3GC-resistant E. coli, respectively. Significance: These results suggested that 3GC resistance in Salmonella was primarily due the persistence of a Montevideo Clade 2 sub-population with very minimal or no contribution from 3GC-resistant E. coli via horizontal gene transfer. These results suggest antimicrobial resistance in E. coli may not be a useful indicator of antimicrobial resistance in Salmonella. Intensive longitudinal WGS studies at commercial feedyards that include detailed records (cattle source, backgrounding processes, feed, and antimicrobial use) will aid the design, monitoring, and assessment of pre-harvest interventions effective against high-priority antimicrobial-resistant Salmonella.