1991 Volume 28 Issue 5 Pages 611-618
To evaluate the efficacy of the single dose chemoprophylaxis of recurrent urinary tract infection (UTI) in the elderly, 20 female inpatients (mean age 81.4) who had one or more culture documented UTIs in the past 12 months were studied. They were randomly assigned to be treated for 6 months either with chemoprophylaxis (200mg of norfloxacin) or conventional therapy (without any antimicrobials except when overt UTI occurred). After a 4 months of washout period, the protocols were exchanged with each other and next 6 months of trial was carried out. All cases were followed at least 4 months after the discontinuance of the chemoprophylaxis. The difference of efficacy between the two modalities was evaluated by periodical examinations of urine cultures, urinalysis and inflammatory markers. During chemo-prophylaxis, the frequency of the symptomatic UTI (bacteriuria>104/ml, pyuria>5/HPF, CRP>+) was 0.267/patient·year which was significantly lower than during convertional therapy (2.97/patient·year, p<0.01). This prophylactic effect remained 4 months after the discontinuance of the drug. On the other hand, bacteriuria was persistent in more than half of patients with chemoprophylaxis. Minimal inhibitory concentration of norfloxacin for separated bacteria revealed that the resistant species steeply increased from 4 to 6 months after the beginning of chemoprophylaxia. These species disappeared 4 months after the drug was discontinued. Optimal durations of chemoprophylaxis and drug-holidays were discussed.