The Role of Streptococcus faecalis in the Antibiotic Growth Effect in Chickens

Abstract

MANY workers have attempted to find a correlation between the antibiotic growth effect and the presence or absence of certain bacterial types in the intestinal tract. The microorganism most often implicated has been Clostridium welchii. Thus, Sieburth et al. (1951) found C. welchii in the cecal contents of turkey poults on normal rations. These were virtually eliminated by feeding 15 p.p.m. oxytetracycline. Lev et al. (1957) found C. welchii in the ceca of birds in infected, but not in uninfected quarters. Lev and Forbes (1959) reported that C. welchii depressed growth of germ-free birds. This depression was reversed when penicillin was fed. Other organisms have also been reported to decrease in numbers when antibiotics were fed. Dixon and Thayer (1951), Anderson et al. (1952), and Sieburth et al. (1954), reported decreases in numbers of enterococci in birds fed antibiotics. Slinger et al. (1954) associated the presence of enterococci in the…