The susceptibility of Swiss White mice to colonization with Streptococcus (Enterococcus) faecalis was greatly increased when the animals were given 5 mg of streptomycin sulfate per ml in their drinking water. One week after initiation of streptomycin treatment, the mice were challenged orogastrically with graded doses of streptomycin-resistant S. faecalis. The , abstr. no. 1029, 1985) reported that nosocomial enterococcal infections had increased from 3.4 to 3.8 per 1,000 hospital discharges between 1980 and 1984; during this same period, the incidence of enterococcal bacteremias almost doubled (0.12 to 0.20 per 1,000 hospital discharges). Overall infection rates were highest on surgery services (5.6 per 1,000 discharges), with the urinary tract, surgical wounds, and blood accounting for 59, 23, and 4% of the infections, respectively. This may represent a shift in the traditional epidemiology of enterococcal infections, which have typically involved the biliary tract, genitourinary tract, or heart valves. Perhaps even more ominous is the fact that isolates recovered from surgical infections are increasingly resistant to aminoglycosides (20).Surgical infections involving enterococci, especially Streptococcus (Enterococcus)faecalis, often occurin seriously ill patients with peritonitis who have received broad-spectrum antibiotic therapy effective against most enteric pathogens except enterococci (5). We have observed that in some of these patients, enterococcal bacteremia may arise even when the organism has not been previously recovered from any known septic focus, including the urinary tract, and in the apparent absence of endocarditis, biliary tract disease, or pus (S. Dougherty, unpublished data). Global depression of host immune defenses usually appears to be present as well. * Corresponding author.We speculate that in seriously ill patients with peritonitis who receive broad-spectrum antibiotic therapy ineffective against enterococci, intestinal overgrowth of these organisms and extraintestinal spread by translocation sometimes occurs.Surprisingly little experimental data exist, however, on the ability of enterococci to translocate to extraintestinal sites (18) or on the ability of specific antibiotic therapy to prevent translocation. In this report, we describe S. faecalis colonization of the intestines of mice and translocation of the organism to extraintestinal sites. We further report on the effectiveness of the experimental antibiotic LY146032 (Eli Lilly & Co., Indianapolis, Ind.) in preventing these extraintestinal infections and in ameliorating infections already established. MATERIALS AND METHODSBacterial strain. The S. faecalis strain was kindly provided by Robert C. Moellering, New England Deaconess Hospital and Harvard Medical School. The MIC of streptomycin sulfate for this strain was greater than 10,000 ,ug/ml.Mice. Outbred Swiss White mice (Cox variety; Laboratory Supply Co., Indianapolis, Ind.) were used in all experiments. The mice were housed individually in cages with wire-mesh bottoms...

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Specimens were obtained before administration of various antibiotics, 7 d after therapy was begun and 28 d after completion of treatment. The antibiotics prescribed were either amoxicillin, ampicillirt, cephalexin, choramphenicol, dicloxocillin, erythromycin, penicillin or trimethroprim/ sulphamethoxazole. Faecal concentrations of total and individual volatile fatty acids (VFA) and faecal pH levels were determined and compared before, during and after treatment with the various antibiotics. Specimens, collected during the same time periods from a group of healthy infants and children who were not taking antibiotics, were evaluated to determine if normal fluctuations occurred between samplings. There were no significant differences in the Texas subjects in total VFA concentrations and pH levels between the patients receiving antibiotics and healthy participants who did not. With the exception of erythromycin administered to Costa Rican patients, therapeutic doses of the antibiotics did not significantly alter total VFA concentrations or pH levels of the faeces. Variations in concentrations of individual VFAs as a consequence of treatment were demonstrated only in Costa Rican patients teceiving either erythromycin or cephalexin; however, the patterns of change were similar to those observed in untreated control participants from Texas and were therefore not attibuted to antibiotic administration. These results are in accordance with our previous studies which show that absorbable antibiotics, administered to mice in therapeutic doses, do not significantly alter total VFA concentrations or pH levels of caecal contents and do not increase the susceptibility of the animals to oral challenge with enteric pathogens.' We speculate that the use of absorbable antibiotics does not compromise natural resistance against infections of the intestinal tract of humans.