Multiclinic study of norfloxacin for treatment of urinary tract infections.

A multicenter open study of 477 patients with urinary tract infections was undertaken. The patients were treated with 400 mg of norfloxacin twice daily for seven to 30 days. Four hundred eight (98 percent) of 417 gram-negative organisms and 58 (94 percent) of 62 gram-positive organisms were susceptible to norfloxacin. The infecting organisms were eradicated in 276 of 307 evaluable patients (90 percent). Of the 31 bacteriologic failures, two organisms were initially resistant to norfloxacin and four organisms acquired resistance to norfloxacin and persisted despite treatment. Twenty-eight patients (10 percent) had recurrent infections; 24 of the 25 organisms involved in these infections were susceptible to norfloxacin. Seventeen patients (3.5 percent) experienced clinical adverse effects that were probably or definitely related to the drug. One adverse reaction was serious. Although norfloxacin was discontinued in two patients because of clinical side effects, none of the patients experienced laboratory adverse effects that were either serious or drug related.