Oral probiotic and prevention of Pseudomonas aeruginosa infections: a randomized, double-blind, placebo-controlled pilot study in intensive care unit patients

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Introduction</jats:title> <jats:p>Preventing carriage of potentially pathogenic micro-organisms from the aerodigestive tract is an infection control strategy used to reduce the occurrence of ventilator-associated pneumonia in intensive care units. However, antibiotic use in selective decontamination protocols is controversial. The purpose of this study was to investigate the effect of oral administration of a probiotic, namely <jats:italic>Lactobacillus</jats:italic>, on gastric and respiratory tract colonization/infection with <jats:italic>Pseudomonas aeruginosa</jats:italic> strains. Our hypothesis was that an indigenous flora should exhibit a protective effect against secondary colonization.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>We conducted a prospective, randomized, double-blind, placebo-controlled pilot study between March 2003 and October 2004 in a 17-bed intensive care unit of a teaching hospital in Clermont-Ferrand, France. Consecutive patients with a unit stay of longer than 48 hours were included, 106 in the placebo group and 102 in the probiotic group. Through a nasogastric feeding tube, patients received either 10<jats:sup>9</jats:sup> colony-forming units unity forming colony of <jats:italic>Lactobacillus casei rhamnosus</jats:italic> or placebo twice daily, from the third day after admission to discharge. Digestive tract carriage of <jats:italic>P. aeruginosa</jats:italic> was monitored by cultures of gastric aspirates at admission, once a week thereafter and on discharge. In addition, bacteriological analyses of respiratory tract specimens were conducted to determine patient infectious status.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>The occurrence of <jats:italic>P. aeruginosa</jats:italic> respiratory colonization and/or infection was significantly delayed in the probiotic group, with a difference in median delay to acquisition of 11 days versus 50 days (<jats:italic>P</jats:italic> = 0.01), and a nonacquisition expectancy mean of 69 days versus 77 days (<jats:italic>P</jats:italic> = 0.01). The occurrence of ventilator-associated pneumonia due to <jats:italic>P. aeruginosa</jats:italic> in the patients receiving the probiotic was less frequent, although not significantly reduced, in patients in the probiotic group (2.9%) compared with those in the placebo group (7.5%). After multivariate Cox proportional hazards modelling, the absence of probiotic treatment increased the risk for <jats:italic>P. aeruginosa</jats:italic> colonization in respiratory tract (adjusted hazard ratio = 3.2, 95% confidence interval – 1.1 to 9.1).</jats:p> </jats:sec><jats:sec> <jats:title>Conclusion</jats:title> <jats:p>In this pilot study, oral administration of a probiotic delayed respiratory tract colonization/infection by <jats:italic>P. aeruginosa</jats:italic>.</jats:p> </jats:sec><jats:sec> <jats:title>Trial registration</jats:title> <jats:p>The trial registration number for this study is NCT00604110.</jats:p> </jats:sec>