Comparison of amikacin and gentamicin in the treatment of urinary tract infections

Abstract

The use of standard doses of gentamicin and small doses of amikacin was compared in the treatment of urinary tract infections in 30 adults. Patients were prospectively randomized to treatment with 3 to 4 mg/kg/day of gentamicin (group 1) or 9 mg/kg/day of amikacin (group 2). The age and sex of the patient, and the duration of the treatment were similar in the two groups. Eleven of the 15 patients in each group were diagnosed clinically as having pyelonephritis. The majority of patients in both groups either required a permanent Foley catheter or had associated diseases predisposing to urinary tract infections. In nine of 15 patients in each group, the bacterial etiology was Pseudomonas aeruginosa. Bacteriologic cures were achieved in nine of 15 patients treated with gentamicin (group 1) and in 10 of 15 patients treated with amikacin (group 2). The mean peak concentration of gentamicin was 5.4 μg/ml (range: 2 to 13 μg/ml), and the mean peak concentration of amikacin was 11.2 μg/ml (range: 8.2 to 19.6 μg/ml). In the patients treated with gentamicin, there was no correlation between the peak serum concentration of gentamicin, the in vitro minimum inhibitory concentration and the bacteriologic response to treatment. No direct evidence of antibiotic-induced toxicity was detected. These results suggest that a reduced amikacin dosage schedule gave results essentially equivalent to standard doses of gentamicin in adults with urinary tract infections.