Epidemiology, prevalence, and sites of infections in intensive care units

Patients in intensive care units (ICUs) have a higher risk of acquiring hospital-associated infections than those in non-critical care areas. ICUs are sites of considerable broad-spectrum antibiotic use, and antibiotic-resistant pathogens are frequent. Bloodstream infections (BSIs), pneumonias, and urinary tract infections (UTIs) are the most common hospital-acquired infections and are most often associated with the use of invasive devices. They differ in importance in different types of ICUs. Coagulase-negative staphylococcus BSIs have recently increased in frequency, and enterococci have been as frequently reported as Staphylococcus aureus as causing BSIs in increasing numbers of U.S. ICUs. Fungal urinary tract sepsis has also increased. Device-associated infection rates represent the most useful surveillance rates for comparison between units and over time, but they differ considerably between ICU types. Outbreaks are common in ICUs. Recently, gram-negative bacilli have been reported more frequently than gram-positives in this setting, especially in NICUs. Considerable crude mortality and major costs are associated with these infections, but controversy persists over the degree of mortality attributable to them.