Transient intestinal carriage after ingestion of antibiotic-resistant Enterococcus faecium from chicken and pork.

Background: Antibiotic-resistant enterococci are often present in retail me ats, but it is unclear whether the ingestion of these contaminants leads to sustained intestinal carriage. Methods: We conducted a randomized, double-blind study in 18 healthy volunt eers. Six ingested a mixture of 10(sup 7) colony-forming units (CFU) of two glycopeptide-resistant strains of Enterococcus faecium obtained from chick en purchased at a grocery store, six ingested 10(sup 7) CFU of a streptogra min-resistant strain of E. faecium obtained from a pig at slaughter, and si x ingested 10(sup 7) CFU of a glycopeptide-susceptible and streptogramin-su sceptible strain of E. faecium from chicken purchased at a grocery store. S uspensions of enterococci were prepared in 250 ml of whole milk and were we ll within the amounts deemed acceptable by Danish food regulations. Stool s amples were collected before exposure, daily for 1 week after ingestion, an d at 14 and 35 days. Resistant enterococci in stools were identified by sel ective culture techniques; further molecular characterization of the organi sms was also conducted. Results: At the outset, none of the subjects were colonized with glycopepti de-resistant or streptogramin-resistant E. faecium. After ingestion of the study strains, these same strains were isolated from the stools of all subj ects, in various concentrations. The test strain was isolated in stool from 8 of 12 subjects on day 6, and from 1 of 12 on day 14. All stool samples w ere negative at 35 days. Conclusions: The ingestion of resistant E. faecium of animal origin leads t o detectable concentrations of the resistant strain in stools for up to 14 days after ingestion. The organisms survive gastric passage and multiply. ( N Engl J Med 2001;345:1161-6.) Copyright (C) 2001 Massachusetts Medical Soc iety.