RESUMEN
OBJECTIVE: To evaluate the efficacy of Escherichia Coli extract (OM-89) in the prophylaxis of recurrent uncomplicated urinary tract infection (UTI) through a contemporary systematic review and meta-analysis. METHODS: Inclusion criteria were double-blind randomized trials using orally administrated OM-89, 6mg daily, during three months with a minimum of three months of monitoring. Outcomes were the frequency of bacteriuria in 3 and 6 months, dysuria in 6 months and UTI in 6 months. DATABASES: PubMed, MEDLINE, Cochrane Collaboration and their key references. After analysis by three independent reviewers, 15 double-blind randomized trials were identified, 10 papers excluded due to methods flaws and 5 used for data analysis due to double blinding and reporting drop-outs. RESULTS: Among 5 selected studies the date of publication ranged from 1985 to 2005, totalizing 396 patients in the OM-89 group and 392 in the control group. Overall, there were 61 dropouts in the control group and 76 in the OM-89 group. As a major limitation there was no appropriate description of their methodologies and none of the studies described conflict of interest or commitment to the pharmaceutical industry. All studies were multi-centric, except for two, which showed no clarity on allocation concealment. All studies show benefit in favor of vaccine. CONCLUSIONS: Current literature on prospective randomized controlled trials evaluating the use of oral OM-89 vaccine in the recurrent UTI prophylaxis is of low quality, limited to the first six months only and with variable definition of bacteriuria and UTI. Although all studies show benefit in favor of vaccine, no robust trial was identified, resulting in a high heterogeneity in the data analyzed. Also, publication bias could not be excluded and future higher quality studies are warranted adding intermediate (>12 months) and long-term follow-up.