The pathogenesis of ventilator-associated pneumonia (VAP) involves a shift from the host’s native, non-pathogenic flora, to an opportunistic, ICU-acquired flora rich in pathogens. We evaluated whether probiotic therapy maintained a non-pathogenic flora in critically ill patients.
40 mechanically ventilated adults were stratified by APACHE II score and randomized to double-blinded administration of 10(9) CFU of Lactobacillus GG or placebo (inactive plant starch inulin) suspended in vehicle and applied to the oropharynx and stomach every 12 hours. Prior to the first dose of study medication (baseline) and 12 hours after the sixth dose of study medicine (72-hour surveillance), semi-quantitative cultures were obtained via oral swab and gastric aspiration while quantitative cultures were obtained by non-bronchoscopic bronchoalveolar lavage (mini-BAL). Patients received study drug and had cultures collected in addition to standard care. Delta scores were calculated from baseline and 72-hour surveillance culture densities. Two-sample t-tests were used to assess between group differences in the mean delta scores.
Baseline characteristics were not different between the groups. Compared to placebo (n=21), Lactobacillus (n=19) was statistically superior at preserving the normal oral flora (Delta semi-quantitative cultures 0.37 vs. –0.45, p=0.03). Although the Lactobacillus group demonstrated trends toward less pathogenic colonization of the mouth (Delta semi-quantitative cultures -0.21 vs. 0.32) and stomach (Delta semi-quantitative cultures -0.11 vs. 0.32), these results were not statistically significant (p=0.45 and 0.35 respectively). Although twice as many placebo patients as Lactobacillus patients had a ≥10(3) increase in quantitative cultures from surveillance mini-BAL (16% vs. 32%) this difference was not statistically significant (p=0.34). Trends toward less clinically diagnosed VAP (26% vs. 45%, p=0.21) and microbiologically confirmed VAP (11% vs. 33%, p=0.08) were seen in the Lactobacillus group. No adverse events attributable to Lactobacillus administration were encountered.
Administration of the probiotic agent Lactobacillus GG to critically ill patients is safe and appears to favorably alter the microbiotic flora in this population.
Probiotic therapy may provide a novel, inexpensive, non-antibiotic opportunity for VAP prevention.
Lee Morrow, Product/procedure echnique that is considered research and is NOT yet approved for any purpose. Lactobacillus GG administration; Other Lactobacillus GG and placebo capsules were generously provided by ConAgra Foods Inc.