Development of germfree animal characteristics in conventional rats in antibiotics.

Conventional (CONV) rats were fed by stomach tube for five days with either benzylpenicillin, ampicillin, tetracykline, oxitetracykline, neomycin, bacitracin + neomycin, kanamycin or colistin. On the 2nd-3rd day all the animals developed one or several of the following symptoms or characteristics typical for germfree (GF) rats: no coprostanol formation, no stercobilin production, a GF pattern after gel electrophoresis of fecal supernatant and proteolytic activity in the feces. Under the same conditions succinylsulfathiazole or metronidazole had much less pronounced effects than the antibiotics. When clofibrate, acetylsalicylic acid or ferrous sulphate were administered the effects were none or negligible. The GF characteristics persisted for several weeks after the end of the administration of the drugs. In some instances this was the case up to 7 weeks, when the animals were contaminated by anal route with a suspension of the cecum contents from intact CONV animals. On the 2nd day after this treatment the GF characteristics had disappeared.