Letters to the Editor.
As data accumulate correlating the use of subtherapeutic antibiotics in livestock (as supplements or feed additives) with the induction of resistance in human bacterial pathogens, the magnitude and complexity of the problem become increasingly clear. Not only is the breadth of the association emerging, but the social and economic dependence on antibiotics in food animals is now also fairly well understood (Hayes, Jensen, Backstrom, & Fabiosa, 1999; Pollan, 2002). Kidd, Rossignol, & Gamroth, in the May issue of the Journal, uncovered yet another thread in this lace of scientific advance, agricultural dependence, and consumer preference when they documented the presence of multidrug-resistant Enterobacteriaceae in commodity feed used on several dairy farms in Oregon. As with most articles on the topic, the conclusions in that paper seem discouraging. Yet there may be a glimmer of good news in the findings. Although widespread resistance to ampicillin, chloramphenicol, streptomycin, and tetracycline was reported for the feed samples tested, ciprofloxacin was uniformly active.
Enterobacteriaceae in general, and Salmonella in particular, have been found variably resistant to ampicillin, chloramphenicol, tetracyclines and sulfonamides in humans for several years (Molbak et al., 1999; Oldfield & Wallace, 2001; U.S. Department of Agriculture, 1999). For that reason, their use in serious infections has been in large part supplanted by quinolones (such as ciprofloxacin) in adults and third-generation cephalosporins in children. Although these two classes of antimicrobials remain generally active against Enterobacteriaceae, widespread resistance remains a threat. Concern has been raised about the finding of ceftriaxone-resistant Salmonella in an ill child living on a Nebraska cattle farm (Fey et al., 2000) and in multiple supermarket meat samples purchased in Washington, D.C. (White et al., 2001). Isolates of ciprofloxin-resistant nontyphoidal Salmonella have been found in the United States since at least 1994 (Herikstad, 1997). Although the earliest identification predated approval of th is class of antibiotic for subtherapeutic animal use, a link to livestock was subsequently established (Molbak et al., 1999). The findings of Kidd, Rossignol, & Gamroth may be most helpful by supporting the evidence that quinolone-resistance continues to remain a relatively rare occurrence and has not yet permeated every phase of animal and dairy production.
The authors of that article need to continue to explore the connection between dairy cattle feed and drug-resistant human pathogens. One would hope that their further characterization and source search would include ongoing investigation of resistance to quinolones. The addition of third-generation cephalosporins to their protocol should also be considered. Such information would be of great benefit in the growing debate on the safety of low-dose antimicrobials as growth promoters in mammals, poultry, and fish raised for human consumption.
Robert S. Goldsmith, M.D.
University of Connecticut School of Public Health
Paul M. Schur, R.S., M.P.H
Assistant Clinical Professor
University of Connecticut School of Public Health
Fey, P.D., Safranek, T.J., Rupp, M.E., Dunne, E.F., Ribot, E., Iwen, P.C., Bradford, P.A., Angulo, F.J., & Hinrichs, S.H. (2000). Ceftriaxone-resistant Salmonella infection acquired by a child from cattle. The New England Journal of Medicine, 342(17), 1242-1249.
Hayes, D.J., Jensen, H.H., Backstrom, L., & Fabiosa, J. (1999). Economic impact of a ban on the use of over-the-counter antibiotics in U.S. swine rations. Staff Report 99 SR 90. Ames: Center for Agricultural and Rural Development, Iowa State University, 1-39.
Herikstad, H. (1977). Emerging quinolone-resistant Salmonella in the United States. Emerging Infectious Diseases, 3(3), 371-372.
Kidd, R.S., Rossignol, A.M., & Gamroth, M.J. (2002). Salmonella and other enterobacteriaceae in dairy-cow feed ingredients: Antimicrobial resistance in western Oregon. Journal of Environmental Health, 64(9), 9-16.
Molbak, K., Baggesen, D.L., Aarestrup, F.M., Ebbesen, J.M., Engsberg, J., Frydendahl, K., Gerner-Smidt, P., Petersen, A. M., & Wegener, H.C. (1999). An outbreak of multidrug-resistant quinolone-resistant Salmonella enterica serotype typhimurium DT104. The New England Journal of Medicine, 341 (19), 1420-1425.
Oldfield, E.C., & Wallace, M.R. (2001). The role of antibiotics in the treatment of infectious diarrhea. Gastroenterology Clinics, 30(3), 817-836.
Pollan, M. (2002, March 31). Power steer. The New York Times Magazine, pp. 44-77.
U.S. Department of Agriculture, Animal and Plant Health Inspection Service and Other Services. (1999). Antibiotic resistance issues in animal agriculture <http://www.aphis.usda.gov/vs/ceah/cei/antiresist.entire.pdf> (6 July 2002), pp. 1-77.
White, D.G., Zhao, S., Sudler, R., Ayers, S., Friedman, S., Chen, S., McDermott, P.F., McDermott, S., Wagner, D.D., & Meng, J. (2001). The isolation of antibiotic-resistant Salmonella from retail ground meats. The New England Journal of Medicine, 345(16), 1147-1154.
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|Publication:||Journal of Environmental Health|
|Article Type:||Letter to the Editor|
|Date:||Oct 1, 2002|
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