Short vs. long cotrimoxazole courses in eradicating bacteriuria in the elderly

To test whether longer duration of treatment of asymptomatic bacteriuria in old age could improve the efficacy of cotrimoxazole therapy, three regimens were given to 75 ambulant bacteriuric residents of a retirement home, aged greater than or equal to 68 years. The groups and regimens were: A:23 subjects (160/800 mg b.i.d. orally x 3 days). B: 24 subjects (160/800 mg i.m. x 10 days); C: 28 subjects (160/800 mg b.i.d. orally x 20 days). One week, one month and five months post-therapy urines were negative in 78.3% vs 52.9% vs 42.9% of group A, in 54.2% vs 56.5% vs 50% of group B and in 57.1% vs 60.7% vs 68% of group C subjects respectively. The data indicate that: 1) the efficacy of any schedule is only moderate irrespective of the presence of antibody-coated bacteria in urine; 2) a 3-day course appears more effective at one week post-therapy; 3) at one and five months greater than or equal to 50% of the subjects were infection-free, the 20 day treatment resulting in fewer failures; 4) subjects with long-term eradication had no mobility problem, low serum creatinine and a normal urinary tract as seen by ultrasound.