Amoxicillin-clavulanic acid versus cefaclor in the treatment of urinary tract infections and their effects on the urogenital and rectal flora.

In a double-blind randomized study, amoxicillin-clavulanic acid (AM-CL) was compared with cefaclor for the treatment of acute urinary tract infections in 107 college women. A total of 53 patients received amoxicillin (250 mg) and clavulanic acid as the potassium salt (125 mg), and 54 received cefaclor (250 mg); each drug was administered every 8 h for 10 days. The cure rates at 1 and 4 weeks after treatment were 96 and 78%, respectively, in the AM-CL group and 92 and 75%, respectively, in the cefaclor group (P greater than 0.10). After AM-CL treatment, the prevalence of amoxicillin-resistant Escherichia coli significantly increased in the rectal flora. Also, the frequency of bacterial resistance to amoxicillin, AM-CL, and cefaclor increased among the urinary pathogens causing subsequent urinary tract infections (P less than 0.05). There were no adverse reactions in the cefaclor group; however, six patients in the AM-CL group (12%) experienced diarrhea, nausea, or vomiting (P less than 0.05). Elevated transaminase enzyme levels were observed in 23% of the patients in the AM-CL group and in 6% of the patients in the cefaclor group (P less than 0.05). Symptomatic Candida vaginitis developed in 16 and 13% of the patients in the AM-CL and cefaclor groups, respectively (P greater than 0.10).