INSIGHTS ALONG THE PATH TO SUSTAINABILITY| November 30, 2005

Tracking Antibiotic-resistant Bacteria from Industrial Animal Production

LANCE B. PRICE, MS, Doctoral Candidate, Department of Environmental Health Sciences, JHSPH

SUMMARY

Antibiotic resistance is an increasing problem in the US and around the world. Strains of bacteria resistant to nearly all known antibiotic therapies have begun to proliferate. The public health consequences of antibiotic resistance are evident—thousands die annually from antibiotic-resistant infections and the excess cost of treating these recalcitrant infections is estimated to be in the billions in the US alone. While some of these bacteria are hospital acquired strains, we have also begun to see an increase in community-acquired antibiotic-resistant infections. The sources of these community acquired strains are often unknown; however, it is suspected that many come from industrial animal production, where billions of animals are fed antibiotics annually.

Despite a great deal of epidemiological evidence demonstrating connections between antibiotic-use in industrial animal production and antibiotic-resistant infections in humans, there have been few studies showing a direct connection between antibiotic-resistant bacteria in food-animal products and antibiotic-resistant infections in humans. A biological marker specific for bacteria that have evolved in the industrial animal production setting would make this challenge much less formidable. However, most attempts to find such a marker have failed. Fortunately, the flippant practice of feeding the arsenic derivative, roxarsone, to broiler chickens by the industrial poultry may provide just such a marker.

Roxarsone is fed to broiler chickens as a growth promoter and to control parasites (coccidia) that are spread from chicken to chicken in confined animal feeding operations (CAFOs). Besides being an effective coccidiostat, roxarsone, also inhibits some bacteria such as Campylobacter spp. (an organism that thrives in poultry CAFOs). Therefore the flock-scale application of roxarsone may select for roxarsone-resistant strains of Campylobacter spp. in this setting. In contrast, roxarsone, is not used to control infections in humans. The fact that this selective force is unique to the industrial animal production setting may make roxarsone resistance a powerful marker for tracking human Campylobacter infections back to this source.

In my presentation, I will present the results from our studies to validate roxarsone resistance as a marker for Campylobacter isolates originating from industrial broiler production.

PRESENTER BIOGRAPHY

Lance Price received his Bachelor’s degree in Microbiology and his Master’s degree in Biology from Northern Arizona University. While completing his thesis work, Mr. Price began working in the Keim Genetics Laboratory. There he characterized ciprofloxacin resistance in Bacillus anthracis and led a research group developing novel molecular tools for tracking B. anthracis and Yersinia pestis. In 2002, Mr. Price matriculated to the Johns Hopkins Bloomberg School of Public Health to study the public health consequences of antimicrobial use in industrial-animal production. Mr. Price has been a fellow with the Johns Hopkins Center for Livable Future since 2003.