Rationale: Enteral administration of probiotics may modify the gastrointestinal environment in a manner that preferentially favors the growth of minimally virulent species. It is unknown whether probiotic modification of the upper aerodigestive flora can reduce nosocomial infections.
Objectives: To determine whether oropharyngeal and gastric administration of Lactobacillus rhamnosus GG can reduce the incidence of ventilator-associated pneumonia (VAP).
Methods: We performed a prospective, randomized, double-blind, placebo-controlled trial of 146 mechanically ventilated patients at high risk of developing VAP. Patients were randomly assigned to receive enteral probiotics (n = 68) or an inert inulin-based placebo (n = 70) twice a day in addition to routine care.
Measurements and main results: Patients treated with Lactobacillus were significantly less likely to develop microbiologically confirmed VAP compared with patients treated with placebo (40.0 vs. 19.1%; P = 0.007). Although patients treated with probiotics had significantly less Clostridium difficile-associated diarrhea than patients treated with placebo (18.6 vs. 5.8%; P = 0.02), the duration of diarrhea per episode was not different between groups (13.2 ± 7.4 vs. 9.8 ± 4.9 d; P = 0.39). Patients treated with probiotics had fewer days of antibiotics prescribed for VAP (8.6 ± 10.3 vs. 5.6 ± 7.8 d; P = 0.05) and for C. difficile-associated diarrhea (2.1 ± 4.8 SD d vs. 0.5 ± 2.3 d; P = 0.02). No adverse events related to probiotic administration were identified.
Conclusions: These pilot data suggest that L. rhamnosus GG is safe and efficacious in preventing VAP in a select, high-risk ICU population. Clinical trial registered with www.clinicaltrials.gov (NCT00613795).