A long-term, multicenter, double-blind study of an Escherichia coli extract (OM-89) in female patients with recurrent urinary tract infections.

Objective: To investigate the long-term preventive effect of the immunotherapeutic OM-89 versus placebo in uncomplicated recurrent UTI in a large cohort of female patients only.

Methods: Adult female patients could enroll in this multicenter, double-blind study if they had acute UTI at the enrollment visit and positive results of urinalysis (> or =10(3)bacteria/ml). Patients received the immunotherapeutic OM-89 or a matching placebo; 1 capsule per day for 90 days, 3 months without treatment, then the first 10 days in Months 7, 8 and 9 and were followed up during 12 months. Primary efficacy criteria were UTI rates over 12 months, distribution of UTIs and proportion of patients with UTI.

Results: A total of 453 patients were treated, 231 in the active group and 222 in the placebo group. Mean rate of post-baseline UTIs was significantly lower in the active group than in the placebo group (0.84 vs. 1.28; p<0.003), corresponding to a 34% reduction of UTIs in patients treated with OM-89. In the active group, 93 patients (40.3%) had 185 post-baseline UTIs, compared to 276 UTIs in 122 patients (55.0%) in the placebo group (p=0.001). The safety profile of OM-89 was good and consistent with that reported in previous studies.

Conclusions: OM-89 significantly reduced the incidence of UTI during the 12 months of the study including 3 months of treatment and three 10-day booster courses. These results confirm that OM-89 is a valuable component of the management of recurrent UTI.