Recruiting or enrolling participants has halted and will not resume

Preventing carriage of potentially pathogenic micro-organisms from the aerodigestive tract is an infection control strategy used to reduce the occurrence of nosocomial infections - including ventilator-assisted pneumonia - in intensive care units. The use of antibiotics is controversial and can lead to adverse effect such as the selection of highly resistant pathogens. The purpose of this study was to investigate the effect of oral administration of a probiotic strain, Lactobacillus, on gastric and respiratory tract colonisation/infection by Pseudomonas aeruginosa strains, according to the concept that an indigenous flora has a protective effect against secondary colonisation.

In this prospective double-blind randomised study, ICU patients receive twice a day either an oral dose of Lactobacillus casei rhamnosus, the available pharmaceutical form, or a placebo. Digestive tract carriage of Pseudomonas aeruginosa is monitored by cultures of gastric aspirates. The occurrence of respiratory tract colonisations / infections is monitored throughout the study. Evaluation criteria are the delay and the rates of gastric P. aeruginosa colonisation and respiratory tract infection or colonisation. Chi-square or two tailed Fisher exact test are used for comparing qualitative variables and Student's t-test or mann-Whitney test for quantitatives variables. The mean of non-acquisition expectancy (NAE), length of stay without P. aeruginosa acquisition, was calculated and P. aeruginosa non-colonized patient rates were estimated and the two groups compared with regard to survival curves from grouped data using the Kaplan Meier method and the Logrank test. Variables with a P. value ≤0.15 in the univariate analysis were included in a logistic regression and a Cox regression model for multivariate analysis.

Inclusion Criteria:

• more than 18 years old
• length of stay longer than 48h
• with a nasogastric feeding tube

Exclusion Criteria:

• - less than 18 years old
• length of stay < 48h
• immunosuppression
• absolute neutrophile count < 500/mm3
• gastro-intestinal bleeding
• contraindicated enteral feeding
• positive P. aeruginosa gastric aspirates or respiratory tract specimens during the first four days after hospital admission