Epidemiological surveillance in the ICU: Certainties and uncertainties

Surveillance for colonization by multidrug-resistant microorganisms (MDR) in patients admitted to intensive care units (ICUs) can be passive or active. Active surveillance (nasal/rectal sampling on admission and weekly) allows for early isolation of asymptomatic carriers, combined with universal or targeted decolonisation. This limits dissemination more than passive surveillance. Knowing which microorganisms to monitor, how often, and the various methodologies are some of the aspects emphasized in this review.