Effectiveness of prophylactic oral and/or vaginal probiotic supplementation in the prevention of recurrent urinary tract infections: A randomized, double-blind, placebo-controlled trial

Abstract Background Widespread antibiotic resistance has sparked interest in the identification of nonantibiotic strategies, particularly probiotics for the prevention of recurrent urinary tract infections (UTIs). We evaluated the effectiveness of prophylactic probiotic supplementation through oral and intravaginal routes in the prevention of recurrent UTIs. Methods This double-blind, placebo-controlled study enrolled 174 premenopausal women with a history of recurrent UTIs and randomized them to 1 of the 4 treatment groups: placebo (G1, oral placebo + vaginal placebo), oral probiotic (G2, oral lactic acid bacteria and bifidobacteria + vaginal placebo), vaginal probiotic (G3, oral placebo + vaginal lactobacilli), and probiotic combination (oral lactic acid bacteria and bifidobacteria + vaginal lactobacilli), for 4 months. Participants were followed up for symptomatic UTIs for 1 year. The primary end points were the number of symptomatic UTIs at 4 months, the proportion of participants with at least 1 symptomatic UTI, and the time to the first symptomatic UTI. Results The incidence of UTI at 4 months in G1, G2, G3, and G4 was 70.4%, 61.3%, 40.9%, and 31.8%, respectively. The mean number of symptomatic UTI recurrences at 4 months was significantly lower (P < .05) in G3 (1.06) and G4 (1.07) compared with G1 (2.1) and G2 (1.63). Further, the time to first symptomatic UTI (days) was significantly longer (P < .05) in G3 (123.8) and G4 (141.8) compared with G1 (69.3) and G2 (71.9). Probiotic supplementations were well tolerated with no serious adverse events. Conclusions Prophylactic supplementation with either vaginal probiotics or in combination with oral probiotics demonstrated effectiveness in preventing recurrent symptomatic UTI episodes. Clinical Trials Registration Registered at Clinical Trials Registry India (CTRI): CTRI/2014/02/004425 (https://ctri.nic.in).