Background Antibiotic-resistant enterococci are often presentin retail meats, but it is unclear whether the ingestion ofthese contaminants leads to sustained intestinal carriage.
Methods We conducted a randomized, double-blind study in 18healthy volunteers. Six ingested a mixture of 107 colony-formingunits (CFU) of two glycopeptide-resistant strains of Enterococcusfaecium obtained from chicken purchased at a grocery store,six ingested 107 CFU of a streptogramin-resistant strain ofE. faecium obtained from a pig at slaughter, and six ingested107 CFU of a glycopeptide-susceptible and streptogramin-susceptiblestrain of E. faecium from chicken purchased at a grocery store.Suspensions of enterococci were prepared in 250 ml of wholemilk and were well within the amounts deemed acceptable by Danishfood regulations. Stool samples were collected before exposure,daily for 1 week after ingestion, and at 14 and 35 days. Resistantenterococci in stools were identified by selective culture techniques;further molecular characterization of the organisms was alsoconducted.
Results At the outset, none of the subjects were colonized withglycopeptide-resistant or streptogramin-resistant E. faecium.After ingestion of the study strains, these same strains wereisolated from the stools of all subjects, in various concentrations.The test strain was isolated in stool from 8 of 12 subjectson day 6, and from 1 of 12 on day 14. All stool samples werenegative at 35 days.
Conclusions The ingestion of resistant E. faecium of animalorigin leads to detectable concentrations of the resistant strainin stools for up to 14 days after ingestion. The organisms survivegastric passage and multiply.
Source Information
From the Department of Microbiological Research and Development, Statens Serum Institut, Copenhagen, Denmark.
Address reprint requests to Dr. Frimodt-Møller at Antimicrobial Resistance Surveillance, Department of Microbiological Research and Development, Statens Serum Institut, 5 Artillerivej, DK-2300 Copenhagen S, Denmark, or at nfm{at}ssi.dk.
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