A Cochrane review included 4 studies with a total of 422 subjects. Better microbiological cure was suggested with oral metronidazole plus probiotic regimen compared with oral metronidazole plus placebo (OR 0.09, 95% CI 0.03 to 0.26; 1 trial, n=106), and with probiotic plus estriol preparation vs placebo plus estriol (OR 0.02, 95% CI 0.00 to 0.47; 1 trial, n=15). Vaginal probiotic capsules compared to metronidazole vaginal gel were not different in microbiological cure (OR 0.27, 95% CI 0.07 to 1.10; 1 trial, n= 35), neither probiotic vs placebo given after open treatment with clindamycin ovules (OR 1.21, 95% CI 0.67 to 2.19; 1 trial, n=217).
Comment: The quality of evidence is downgraded by various shortcomings in study quality and by imprecise results (limited study size for each comparison).