Clinical review: Probiotics in critical care

Patients in ICUs represent a relatively small subgroup of hospitalised patients, but they account for approximately 25% of all hospital infections. Approximately 30% of ICU patients suffer from infection as a complication of critical illness, which increases the length of ICU stay, morbidity, mortality and cost. Gram-negative bacteria are the predominant cause of ICU-related infections and with the rise in multidrug-resistant strains we should focus our attention on nonantibiotic strategies in the prevention and treatment of nosocomial infections. Probiotics have been proposed as one option in this quest; however, mechanisms of action in the critically ill population require further investigation. Some of the beneficial effects appear to be associated with improvement in gastrointestinal barrier function, restoration of normal intestinal permeability and motility, modification of the balance of intestinal microbiota and immunomodulation. However, the information we have to date on the use of probiotics in the critical care setting is difficult to interpret due to small sample sizes, differences in ICU populations, the variety of probiotic combinations studied and differences in administration techniques. In this review we shall examine the use of probiotics in the critical care setting, look at some of the proposed mechanisms of action and discuss their potential benefits and drawbacks.