Risk factors for mortality of nosocomial bacteraemia in intensive care units

Abstract

Objective: The aim of this study was to follow critically ill patients prospectively in intensive care units (ICUs) to determine risk factors for mortality and outcome associated with nosocomial bacteraemia (NB).

Subjects and methods: A case-control study of 176 patients was conducted to identify the risk factors for mortality of NB in ICU patients. The study was performed in emergency, surgical and general surgical ICUs with 23 beds during a 15-month period. A total of 1,450 patients were admitted to the ICUs during the study period. The USA Center for Disease Control and Prevention definitions were used to diagnose nosocomial infections. Nosocomial bacteraemia was defined as the isolation of one or more organisms from blood cultures taken at least 48 h after admission, which were not related to a problem present on admission. An assessment of whether the isolated organisms represented true bacteraemia rather than contamination was made by clinical or laboratory evidence of infection.

Results: A total of 214 bacteraemia episodes were found in the 176 patients (64 female, 112 male; 51.3 +/- 21.3 years old), 90 of whom died and 86 survived. The bacteraemia rate was 12.1%. The most common etiological agents of bacteraemia were Klebsiella pneumoniae: 46 (21.5%), methicillin-resistant Staphylococcus aureus: 46 (21.5%), Pseudomonas aeruginosa: 32 (14.9%), and Escherichia coli: 20 (9.3%). Multivariate analysis showed that the requirement of mechanical ventilation for more than 7 days (p < 0.001), total parenteral nutrition (p = 0.034), inotropic drug (p < 0.001), and increased creatinine level (p = 0.034) were independent risk factors for mortality of NB in ICUs.

Conclusions: Nosocomial infections caused by Gram-negative bacteria continue to be one of the major sources of morbidity and mortality.