In-vitro activity of fleroxacin against isolates causing complicated urinary tract infections and concentrations in seminal and prostatic fluid and in prostatic adenoma tissue.

Fleroxacin is a new fluoroquinolone with a broad antibacterial spectrum and a serum half-life of about 8-12 h. Eighty percent of 400 isolates from complicated or hospital-acquired urinary tract infections were inhibited by a concentration of 1 mg/l and 95% by 4 mg/l. As with other quinolones, fleroxacin is less active in acid urine (pH 5.4) than in Mueller-Hinton broth (pH 7.4). In 12 healthy volunteers the concentrations of fleroxacin were measured in plasma and seminal and prostatic fluid 2, 4 and 12 h after an oral dose of 400 mg. The mean plasma concentrations of three or four volunteers at each time were 4.2, 3.6 and 1.2 mg/l, respectively. The corresponding prostatic fluid/plasma ratios were 0.30, 0.27 and 1.96, respectively. By concomittant administration of ioxitalamic acid it could be demonstrated that in samples obtained 12 h after administration urinary contamination must be considered. Fleroxacin is concentrated in seminal fluid by a median ratio of 1.7. In 13 elderly patients the prostatic fluid and prostatic adenoma tissue concentrations were determined one to four hours following oral administration of 400 mg. The concentrations in prostatic fluid were similar to those of volunteers. The tissue concentrations exceeded plasma concentrations by only about 10% (median). Fleroxacin is very active against isolates causing complicated UTI. Concentrations in seminal and prostatic fluid and prostatic adenoma tissue are sufficiently high to treat bacterial prostatitis or vesiculitis caused by susceptible bacterial strains.