Selective elimination of Enterobacteriaceae species from the digestive tract in mice and monkeys

In mice and in monkeys, ;selective' elimination of Enterobacteriaceae species from the digestive tract of animals with a sensitive flora was accomplished by oral treatment with nalidixic acid (1 mg./g. body weight in mice and 0.4 mg./g. body weight in monkeys). During treatment, the concentration of enterococci (and also of Candida albicans in the monkey) remained unaltered. This indicates that the fraction of the anaerobic microflora which is responsible for the colonization resistance of the digestive tract is not affected by the treatment. An important consequence seems to be, that elimination of yeast and fungi with fungistatic drugs can be started at the same time as elimination of Enterobacteriaceae is attempted.