Prevention of nosocomial infection in the intensive care unit

Abstract

Traditional approaches to definitions of nosocomial infections and their prophylaxis focus on time cut-offs and nonantibiotic maneuvers. In general, the time cut-off of 48 hours has been applied to distinguish community and hospital infection from intensive care unit (ICU) infection, and hand washing has been the cornerstone of conventional policies for the prevention of ICU infections occurring after 48 hours. In contrast, the philosophy of antibiotic prophylaxis using selective decontamination of the digestive tract is based on the criterion of the carrier state of a limited range of potential pathogens that are involved in three different types of infection: endogenous infections, both primary and secondary, and exogenous infections. Most infections are of primary endogenous development due to microorganisms carried in the admission flora and are controlled by the parenteral cefotaxime administered immediately on admission. The aim of polymyxin E/tobramycin/amphotericin B applied topically in the throat and gut is to prevent secondary endogenous infections due to microorganisms acquired on the unit, and generally occurring after 7 days. Exogenous infections caused by microorganisms not previously carried can occur at any time during the stay on the unit and only high standards of hygiene are able to prevent them. The most extensive meta-analysis reports data on 5,727 patients enrolled in 33 randomized trials and indicates a significant reduction of both infections (OR = 0.35; 95% CI = 0.29–0.41) and total mortality (OR = 0.80; 95% CI = 0.69–0.93). No randomized trials showing that rigid implementation of hand washing reduces morbidity or mortality are available. The aim of this review is to help readers distinguish between what is evidence-based and what is still largely opinion-based.