Impact of Lactobacillus acidophilus on the normal intestinal microflora after administration of two antimicrobial agents

Twenty healthy volunteers participated in a comparative study concerning the influence of Lactobacillus acidophilus supplements on the normal intestinal microflora after the administration of two antimicrobial agents, enoxacin and clindamycin, respectively. L. acidophilus NCFB 1748 was given as a fermented milk product containing 5 × 10⁸-2 × 10⁹ CFU/ml to ten of the volunteers immediately after the administration of the antimicrobial agents. On the seventh day of enoxacin administration enterobacteria were eliminated in nine of ten subjects. Enterococci disappeared or decreased significantly in five subjects. During the L. acidophilus supplementation, there was a significant increase in the number of Escherichia coli in one subject, while enterococci returned to the same level as before enoxacin administration in all subjects. In the clindamycin group, the anaerobic microflora was strongly suppressed in all volunteers. Lactobacilli disappeared in two subjects and decreased in five. Administration of L. acidophilus resulted in a significant increase in the number of lactobacilli in all subjects, while most other anaerobic bacteria returned to the same levels as before clindamycin administration one week later. In two subjects, Bacteroides increased to earlier high levels on days 14 to 16 in the Lactobacillus group, while there was no similar increase in the clindamycin group. Though there was a partial restoration of the intestinal microflora due to the reestablishment of lactobacilli and enterococci, L. acidophilus administration could not accelerate the normalization of most other strongly suppressed microorganisms in the intestine.