Farm animals as a putative reservoir for vancomycin-resistant enterococcal infection in man

Using a highly selective enrichment broth, 62 isolates of vancomycin-resistant Enterococcus faecium were obtained from non-human sources; 35 isolates from raw sewage, 22 from farm animals and 5 from uncooked chickens. All strains possessed the Van A gene, conferring high-level resistance to vancomycin (MIC ≧ 256 mg/L). Ribotyping of 42 of these isolates resulted in 14 distinguishable patterns. Two ribotyping patterns were found among isolates from animals and sewage and those from clinical sources. A blood and a urine isolate from separate hospital patients and porcine isolates shared the same ribotyping pattern number 6 and a stool isolate from a patient in the community and sewage isolates shared another pattern, number 10. This finding suggests that animals may serve as a reservoir of vancomycin-resistant enterococci (VRE), which may enter the human food chain. The emergence of VRE in hospital patients may reflect selection of these organisms in the hospital environment by antibiotic usage from which nosocomial spread might occur.