COMPARISON OF AMPICILLIN AND NALIDIXIC ACID IN THE TREATMENT OF URINARY TRACT INFECTIONS CAUSED BY E. COLI

. A comparative study of ampicillin and nalidixic acid in short-term treatment of urinary tract infections caused by E. coli has been carried out in a series of female out-patients. Twenty-six patients were treated with ampicillin at a daily dosage of 2 g and 41 with nalidixic acid at a daily dosage of 4 g. Duration of treatment was 14 days in both groups. The frequency of primary resistance of E. coli to ampicillin was 13/67 (19%), whereas primary resistance to nalidixic acid was not found. Development of secondary resistance to ampicillin during treatment did not occur. Secondary resistance to nalidixic acid developed in only one of the 41 cases. In acute infections the cure rate was 14/15 (93%) in the ampicillin group and 18/19 (95%) in the nalidixic acid group. In patients with chronic infections the cure rates were 9/11 (82%) and 17/22 (77%), respectively. In contrast to previous reports, development of secondary resistance to nalidixic acid was not common. The rather favourable results obtained with nalidixic acid must be weighed against a relatively high frequency of side-effects in patients treated with this drug.