Monocontamination with E. coli and dicontamination with E. coli and multidrugresistant Lactobacillus acidophilus were performed on each group of five mice. Antibiotics such as SM, CP, TC and EM were administered orally to each group.
The administration of 100 mg/kg of SM to the gnotobiotic mice monocontaminated with E. coli caused marked decreases of viable cells in the stools in some of the mice, but the administration of the same amount of other antibiotics did not show any change of viable cell count in the stool. The administration of 1000 mg/kg of each antibiotics to the mono-contaminated gnotobiotic mice caused marked decreases of viable cells in the stools of all mice. The administration of100 mg/kg of each antibiotics to the gnotobiotic mice dicontaminated with E. coli and Lactobacillus did not cause any change of viable cell count in the stool of all mice.
Transfer of drug resistance of Lactobacillus to E. coli was not noted in the dicontaminated mice without any antibiotics administration.
The administration of SM to each mono-and dicontaminated mice caused decreases of viable cells in any parts of the alimentary tract but the administration of TC resulted in decreases of viable cells only in small intestine. It seemed that TO was absorbed in the upper part of the small intestine and did not influence on the count of viable cells in the large intestine.