Little is known about the epidemiology of antibiotic-resistant enterococci in the community. One source of resistant enterococci may lie in the feces of meat animals, including poultry, cattle, swine, and sheep. At least 80% of poultry are now given antibiotics in their feed. Debate occurs over the possible hazards of this practice. We evaluated the antimicrobial resistance of enterococci cultured from three separate turkey flocks on two farms of a large poultry production company.
From 125 separate cloacal cultures from three turkey flocks fed virginiamycin, 104 Enterococcus faecium and 186 Enterococcus faecalis isolates were obtained. As the turkeys aged, there was a higher percentage of quinupristin-dalfopristin-resistant E. faecium isolates, with isolates from the oldest flock being 100% resistant. There were no vancomycin-resistant enterococci.
The significance of the findings of this study are that we found quinupristin-dalfopristin-resistant strains in animals before the drug combination had been utilized in humans. Quinupristin-dalfopristin has completed phase III clinical trials in the United States and Europe. Initial studies have shown that the quinupristin-dalfopristin combination has promise as an agent for serious vancomycin-resistant enterococcal infections. Since antibiotic-resistant bacteria that can cause human infection may be transferred via food from animals to humans, until further information is available, great caution should be exercised in the use of streptogramins in animals.
Welton LA, Thal LA, Perri MB, Donabedian S, McMahon J, Chow JW, Zervos MJ
Antimicrob Agents Chemother 1998; 42:705-708