High relapse rates and low tolerability to ampicillin characterize present therapy for carriers of Salmonella typhi. Norfloxacin, a carboxyquinolone with a 90% minimum inhibitory concentration for S. typhi of less than or equal to 0.5 micrograms/mL, is a promising alternative. Carriers of S. typhi were treated in a double-blind trial with either norfloxacin (400 mg) or matching placebo given every 12 h for 28 d. Twelve assessable individuals were treated in each group. After therapy, 11 of 12 individuals treated with norfloxacin had negative stool and bile cultures for S. typhi. All placebo-treated carriers still had positive cultures immediately after therapy. Subsequently, 11 individuals were treated openly with norfloxacin. S. typhi was eradicated in seven of 11. Overall, the eradication rate for 23 individuals treated with norfloxacin was 78%. Eighteen individuals were followed up for one year, and their stool and/or bile cultures remained negative. From our results, norfloxacin is an effective and well-tolerated antimicrobial agent for eradicating the chronic typhoid carrier state.

Forty patients with urinary tract infections were randomly assigned to receive a ten-day course of oral therapy with either norfloxacin 400 mg twice daily or cotrimoxazole (trimethoprim-sulfamethoxazole) 160/800 mg twice daily. There were 34 cases (19 in the norfloxacin and 15 in the cotrimoxazole group) of evaluable infections due to Escherichia coli (85% of cases), Klebsiella pneumoniae, Enterobacter spp., Proteus vulgaris and Alcaligenes faecalis. All organisms were sensitive to the assigned study drug. Twenty-two strains of Escherichia coli and five other isolates had a norfloxacin MIC50 of 0.03 mg/l and MIC90 of 1.0 mg/l. All patients were cured of the initial infection. Three diabetic patients in the norfloxacin group and another healthy patient in the cotrimoxazole group experienced asymptomatic recurrences due to organisms of the same species which, in the absence of causes of bacterial persistence, were considered to be reinfections. Mild reversible adverse effects of no clinical significance were observed in nine patients in each treatment group. Norfloxacin seems to be as effective and safe as cotrimoxazole in the conventional treatment of uncomplicated urinary tract infection.

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