Probiotic Use for the Prevention of Antibiotic- Associated Clostridium difficile Infection

Review of Probiotoc Literature

Conflicting data exist about probiotics and their effect on CDI prevention. The literature reviewed was selected based on our assessment of its contribution to the topic and its potential utility to clinicians in determining appropriate probiotic therapies and recommendations. Included in our discussion is a large Cochrane Review of probiotic efficacy, 2 trials of probiotic dosing, the PLACIDE trial, and a systematic review of timely probiotic initiation. All of these studies attempted to determine the effect of probiotics on CDI incidence (Table).

In their 2017 Cochrane Review, Goldenberg and colleagues reviewed 39 trials that investigated the efficacy of probiotics in CDI prevention in 9,955 immunocompetent patients receiving antibiotics.¹⁵ The incidence of CDI was significantly lower in patients who received a probiotic than in patients who received placebo or no treatment (1.5% vs 4.0%; relative risk [RR], 0.40; 95% CI, 0.30-0.52; I² = 0%). It is important to note that trials with a control-group CDI incidence of 0% to 2% (baseline CDI risk) found no statistically significant difference in CDI risk between patients using and not using probiotics (RR, 0.77; 95% CI, 0.45-1.32; I² = 0%) and that the preceding statistically significant result may have been driven by the inclusion of trials with high baseline CDI risk (> 5%). Trials that enrolled patients who were at this risk level found a statistically significant 70% reduction in CDI risk in those using probiotics (vs no probiotics) while on concomitant antibiotic therapy (RR, 0.30; 95% CI, 0.21-0.42; I² = 0%).

Probiotic therapy seems to be effective in reducing CDI risk in immunocompetent patients and may be particularly beneficial in patients at higher CDI risk, though Goldenberg and colleagues did not elaborate on what constitutes higher risk and based their conclusion on their control group’s high CDI incidence (> 5%). The most common adverse events (AEs) attributable to probiotics included abdominal cramping, nausea, fever, soft stools, flatulence, and taste disturbance. The review’s findings are limited in that the inclusion of many small trials with high baseline CDI risk likely contributed to a statistically significant result, and 17 of the review’s 39 trials were industry-sponsored or were conducted by investigators with industry associations; another 12 lacked statements about funding or sponsorship.

Two of the trials in the Cochrane Review investigated whether probiotics have a dose effect on CDI prevention. Gao and colleagues randomly assigned 255 hospitalized Asian patients to 3 groups: those receiving placebo, 1 probiotic capsule daily, and 2 probiotic capsules daily.¹⁶ Each probiotic capsule contained 50 billion colony-forming units (CFUs) of Lactobacillus. Incidence of CDI was lower in patients taking 2 probiotic capsules daily than in those taking 1 probiotic capsule daily (1.2% vs 9.4%; P = .04) or placebo (1.2% vs 23.8%; P = .002). In the other trial, Ouwehand and colleagues randomly assigned 503 hospitalized Asian patients to 3 groups as well: those receiving placebo, low-dose probiotic (4.17 billion CFUs of Lactobacillus and Bifidobacterium), and high-dose probiotic (17 billion CFUs).¹⁷ The incidence of CDI in each probiotic group (low-dose, high-dose) was 1.8%, which was significantly lower than the 4.8% in the placebo group (P = .04).

The Cochrane Review’s largest and most rigorous trial was PLACIDE, a 2013 randomized controlled study of the effect of probiotics on CDI.¹⁸ Allen and colleagues randomly assigned 2,981 inpatients (aged ≥ 65 years; exposed to antibiotics within preceding 7 days) to 2 groups: those receiving either 1 probiotic capsule daily, or 1 placebo capsule daily, for 21 days. Results showed no difference in CDI incidence between the probiotic and placebo groups (0.8% vs 1.2%; RR, 0.71; 95% CI, 0.34-1.47; P = .35). Of note, this trial is free of industry sponsorship, is the largest probiotic trial to date, has a control-group baseline CDI rate consistent with the rate in hospital and ambulatory settings in the US, and found a negative result regarding probiotic use in CDI prevention. Findings are limited in that the study allowed for initiating probiotic therapy up to 7 days after the start of antibiotics, and patients were given 1 relatively low-dose capsule daily, which may have contributed to lack of an effect on CDI prevention. No serious AEs were attributed to probiotic use.

In a 2017 systematic meta-analysis of 19 studies, Shen and colleagues investigated whether timely use of probiotics prevented CDI in 6,261 hospitalized patients receiving antibiotics.¹⁹ The incidence of CDI was significantly lower in patients receiving vs not receiving probiotics (1.6% vs 3.9%; RR, 0.42; 95% CI, 0.30-0.57; I² = 0%; P < .001).¹⁹ A subgroup analysis was performed to compare studies initiating probiotics within 2 days after the start of antibiotics with studies initiating probiotics more than 2 days after the start. CDI risk was reduced by 68% when probiotics were started within 2 days, vs 30% when started after 2 days (RR, 0.32; 95% CI, 0.22-0.48; I² = 0% vs RR, 0.70; 95% CI, 0.40-1.23; I² = 0%; P = .02). Of note, no difference was found in efficacy among the various probiotic formulations, and no significant AEs were noted in any study group.

Trials included in the Cochrane Review used many different probiotic regimens over various durations.¹⁵ All these trials continued probiotics for at least the duration of antibiotic therapy. The 2 trials that evaluated the effect of probiotic therapy over an extended period required probiotics be started within 48 hours after initiation of antibiotic therapy; one trial continued probiotics for 5 days after completion of antibiotics, and the other for 7 days after completion.^16,20 In both trials, CDI was statistically significantly reduced among adults using probiotics compared with adults receiving placebo.