An alternative approach to treatment of recalcitrant CDI is to restore the damaged microbial intestinal communities. The efficacy of the probiotic Saccharomyces boulardii as an adjunct to antibiotics has been tested in 2 trials. Although it did not decrease recurrence rates in those with their first episode of CDI (19% compared with 24% with placebo), it did decrease the frequency of relapses in those with recurrent CDI (34.6% vs 64.7% with placebo). 10 However, a second trial showed S boulardii had efficacy only in the subset of patients who were given high-dose vancomycin (2 g/d) (16.7% compared with 50% with placebo). No significant benefit was seen in those given metronidazole or lower-dose vancomycin. 15 Although the probiotic Lactobacillus GG showed promise in case reports, recurrence rates were worse than placebo (37.5% vs 14.3% with placebo). 16 In a controlled, albeit underpowered, trial of L plantarun 299v as an adjunct to metronidazole in 11 patients with recurrent CDI, the probiotic arm had a lower recurrence rate (36%) compared with placebo (66%). 17 The data to date indicate that probiotics might have a role in treatment, but their efficacy is less than ideal.