Submitted to: Pig Veterinary Society International Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/20/2002
Publication Date: 7/2/2002
Citation: Ladely, S.R., Cray, P.J., Reeves, D.E. 2002. Multiple antimicrobial resistance of bacterial isolates from an on farm study. Pig Veterinary Society International Congress Proceedings. V. 1. Paper 69. P. 239. Interpretive Summary:
Technical Abstract: The development of antimicrobial resistant bacteria in food producing animals has initiated a debate over antimicrobial use in animal production. The objective of this study was to determine the effect different antimicrobial use patterns have on the development and persistence of antimicrobial resistance among different bacterial spp. on the farm. Three swine farms were selected based on their antimicrobial uses; antimicrobials were used therapeutically and subtherapeutically on farm A and B, whereas farm C had no antimicrobial use for the past 28 years. The farms were sampled quarterly for 2 years. Fecal samples from sows (gestating and lactating) and pigs (suckling, nursery, and finishing) were cultured for Salmonella, Campylobacter, Enterococcus, and generic E. coli. All Salmonella isolates and subsets of the Campylobacter and E. coli isolates were evaluated for susceptibility to antimicrobials. Salmonella and E. coli isolates were evaluated using a semi-automated system (Sensititre, Trek Diagnostics, Westlake, OH) and Campylobacter were tested using the E-Test (AB Biodisk, Piscataway, NJ). Enterococci isolates have not been analyzed. The antimicrobials and breakpoints used were similar to those used in the NARMS program. Multiple resistance is defined as resistance to >=2 antimicrobials. Salmonella isolates recovered from farm C were sensitive to all antimicrobials and tested. In contrast, for isolates recovered from farms A and B; 2.6% (Farm A) and 0% (Farm B) were resistant to a single antimicrobial; and 7.8% (Farm A) and 63.9% (Farm B) were multi-resistant. When comparing the Campylobacter isolates among farms, 16.1%, 40.2% and 6.6% were resistant to a single antimicrobial, while 55.9%, 48.0% and 26.3% were multi-resistant for farms A, B and C respectively. These data indicate that resistance profiles differ dramatically between bacterial spp. The differences in resistance profiles among bacterial spp. further complicates the development of a global consensus regarding antimicrobial use in animal production.