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United States Department of Agriculture

Agricultural Research Service

Title: Comparison of Antimicrobial Resistance Patterns in An Integrated Swine and Human Population

Authors
item Harvey, Roger
item Campbell, L - TX A&M UNIVERSITY
item Scott, H - TX A&M UNIVERSITY
item Andrews, Kathleen
item Bischoff, Kenneth
item Sheffield, Cynthia
item Anderson, Robin

Submitted to: Pig Veterinary Society International Congress Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: February 17, 2004
Publication Date: June 27, 2004
Citation: Harvey, R.B., Campbell, L.D., Scott, H.M., Andrews, K., Bischoff, K.M., Sheffield, C.L., Anderson, R.C. 2004. Comparison of antimicrobial resistance patterns in an integrated swine and human population. Proceedings of 18th International Pig Veterinary Society Congress. 2:517.

Technical Abstract: It is generally perceived by the medical community that increased antibiotic resistance in human infections has been generated by continuous use of subtherapeutic antibiotics as growth promoters in animal production. While this sounds plausible in theory, no definitive studies have established this as fact. Evidence that antimicrobial resistant bacteria (AMR) have been transmitted to humans is at best circumstantial, and based primarily on qualitative data from case reports. Controlled epidemiological studies with stable human and animal populations are needed to better identify the transmission dynamics of AMR. The objective of the present study was to generate data on the prevalence, antibiotic resistance profiles, and potential transmission dynamics of enteric bacteria [Escherichia coli (EC) and Enterococcus faecium (EF)] in an integrated, semi-closed population of swine and humans. In this phase of the study, we tested 450 human wastewater samples and 100 swine samples. Fifteen vancomycin-resistant EF (VRE) have been isolated from human wastewater samples and none from swine fecal samples. Each VRE was ribotyped. VRE isolates of the same ribogroup were found at human housing units that were located geographically close to each other. Surprisingly, antibiotic resistance in many of the EC isolates was low and the resistance pattern most commonly observed was to tetracycline. PCR analysis for genetic markers was performed on 108 EC isolates with 20% PCR positive to at least 1 resistance marker. Six of these isolates have been gene-sequenced, with 3 positive for integrons coding for aminoglycoside resistance and dihydrofolate reductase. Sensititre results confirmed that these isolates had resistance to aminoglycosides and trimethoprim/sulfathoxazole. The present study was intended to be an initial short-term longitudinal one, yet resistance patterns indicate further study is warranted. To this effect, we will conduct a larger 3-year longitudinal study, beginning in 2004.

Last Modified: 8/21/2014