Antibiotic susceptibility of periurethral anaerobic microflora in healthy girls.

The in vitro susceptibility of sixty-four isolates of periurethral anaerobic bacteria to nine commonly used antibiotics was analyzed. Using a quantitative sampling method, the three predominant anaerobic strains were isolated from each periurethral sample of twenty-one healthy prepubertal girls. The majority of strains showed high sensitivity to ampicillin and phenoxymethylpenicillin, whereas trimethoprim and trimethoprim--sulfamethoxazole showed no or only slight inhibition of growth of most strains. Intermediate sensitivity was found to erythromycin, cefuroxime, pivmecillinam, norfloxacin and nitrofurantoin. Our data suggest that several antibiotics used in paediatric praxis might influence the indigenous periurethral anaerobic microflora. Hypothetically, this may be a factor of importance in the pathogenesis of ascending urinary tract infections.