Should selective digestive decontamination be used in critically ill patients?

Healthcare associated infection represents a major burden for critically ill patients; a recent point prevalence survey by the Health Protection Agency observed that 23.4% of patients in intensive care units had evidence of a healthcare associated infection.Ventilator associated pneumonia remains the leading cause of nosocomial infection in this population, and, although recent estimates of attributable mortality (5-10%) are lower than previously thought, length of stay and treatment costs are substantially increased. 3 Colonisation of the oropharynx with enteric bacteria is considered a key step in the development of ventilator associated pneumonia and offers a potential site for intervention with oropharyngeal decontamination. Selective digestive decontamination involves the administration of topical, non-absorbable antibiotics to the oropharynx and stomach via a nasogastric tube in combination with parenteral antimicrobials to reduce the burden of potentially pathogenic bacteria in the aerodigestive tract. Some studies have focused on decontamination strategies limited to the oropharynx alone (selective oral decontamination), avoiding enteral and intravenous antibiotics. Selective digestive decontamination was first used for immunocompromised haematology patients, but this intervention has been extensively studied in intensive care units over the past three decades. However, many clinicians remain sceptical as to whether this evidence is applicable to different healthcare systems, which vary according to environment and antibiotic resistance rates, and their own clinical practice. What is the evidence of uncertainty?