Effect of Lactobacillus F19 on the emergence of antibiotic- resistant microorganisms in the intestinal microflora

Objectives: Probiotic lactic-acid-producing bacteria have been used for prevention of gastrointestinal diseases. The aim of the present study was to examine whether Lactobacillus F19 in conjunction with treatment with penicillin, ciprofloxacin or norfloxacin prevents establishment of resistant bacteria in the gastrointestinal tract. Methods: Twenty patients admitted to hospital due for treatment with penicillin and 16 patients due for treatment with ciprofloxacin or norfloxacin were included in the study. In either group, the patients were randomized into two groups, receiving placebo or an active probiotic product. Faecal samples were collected before treatment, on day 10 and 1 month after the start of the treatment. Isolates of enterococci, enterobacteria and Bacteroides fragilis species were screened for resistance to penicillin and ciprofloxacin, respectively. Results: Administration of penicillin did not influence resistance in enterococci while quinolone resist-ance increased during quinolone treatment. Susceptibility to ampicillin and piperacillin/tazobactam decreased in enterobacteria during penicillin treatment and ciprofloxacin resistance increased in the quinolone group. Penicillin and quinolones did not influence the resistance rates of Bacteroides iso-lates. No major differences were observed between the probiotic- and placebo-supplemented groups. Conclusions: There was a limited effect of Lactobacillus F19 on the emergence of resistant isolates during treatment with penicillin and quinolones