Now, however, a randomized, controlled trial (RCT) of a lactobacilli/bifidobacteria combination in antibiotic-exposed adults over 65 years of age showed no difference in AAD (10.8% in treatment vs. 10.4% in control group) or C. difficile (0.8% vs. 1.2%). The trial was fairly large (almost 3,000 patients enrolled), large enough that one would hope to see a difference in AAD, but the overall C. difficile rate was too low to say much (confidence interval for RR was 0.34-1.47). One major finding hidden in Table 3 of the manuscript: The treatment group had a statistically-significant increase in flatus (insert fart noises here).
What to do with this seemingly contradictory finding? A single negative RCT, performed in a narrowly defined population (inpatients over the age of 65) doesn’t exclude a potential benefit from probiotic use in other groups or if tested in a larger population with a higher baseline incidence of C. difficile.
This does serve as another reminder, though, that when it comes to probiotics, there’s no substitute for the real thing.
Daniel J. Diekema, MD, FACP, practices infectious diseases, clinical microbiology, and hospital epidemiology in Iowa City, Iowa, splitting time between seeing patients with infectious diseases, diagnosing infections in the microbiology laboratory, and trying to prevent infections in the hospital. This post originally appeared at the blog Controversies in Hospital Infection Prevention.
