Hospital-Acquired Infections Linked to Increased ICU Mortality

Healthcare-acquired infections greatly increase the risk for mortality in patients admitted to the intensive care unit (ICU), but antimicrobial resistance has little additional effect, according to the results of a new study.

Researchers at the Scientific Institute for Public Health (Brussels, Belgium) and other institutions conducted a prospective cohort study that involved 119,699 patients admitted between January 1, 2005, and December 31, 2008, for more than 2 days to 537 ICUs in 10 countries. The researchers assessed 20 different healthcare-associated infections according to infection site, microorganism (Acinetobacter baumannii, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa), and resistance to ceftazidime, third-generation cephalosporins, and oxacillin. The outcomes for every exposure were compared for exposed and unexposed patients, after adjustment for patient factors and time-dependency of the exposure.

The results showed that the hazard ratio (HR) for death from pneumonia ranged from 1.7 for drug-sensitive S. aureus to 3.5 for drug-resistant P. aeruginosa. For bloodstream infections, the excess risk ranged from 2.1 for drug-sensitive S. aureus to 4.0 for drug-resistant P. aeruginosa. Risk for death from antimicrobial resistance (in addition to risk for death because of the infection) was 1.2 for pneumonia for a combination of all 4 bacterial species studied, and 1.2 for bloodstream infections. Because of the high prevalence of P. aeruginosa and the pathogenicity of both its drug-sensitive and drug-resistant strains, this microorganism was associated with the highest burden of healthcare-acquired infections. The study was published early online on December 1, 2010, in Lancet Infectious Diseases.

"Healthcare-associated bloodstream infections and pneumonia greatly increase mortality and increase length of stay in intensive-care units; the additional effect of the most common antimicrobial resistance patterns is comparatively low,” concluded lead author Marie-Laurence Lambert, MD, and colleagues of the healthcare-associated infections unit. "Prevention of health-care-related infections needs to be reasserted and emphasized as an absolute priority.”

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