Intensive care unit-acquired urinary tract infections in a regional critical care system

Few studies have evaluated urinary tract infections (UTIs) specifically acquired within intensive care units (ICUs), and the effect of such infections on patient outcome is unclear. The objectives of this study were to describe the occurrence, microbiology, and risk factors for acquiring UTIs in the ICU and to determine whether these infections independently increase mortality.

A surveillance cohort study was conducted among all adults admitted to multi-system and cardiovascular surgery ICUs in the Calgary Health Region (CHR, population about 1 million) between 1 January 2000 and 31 December 2002.

During the 3 years, 4465 patients were admitted 4915 times to a CHR ICU for 48 hours or more. A total of 356 ICU-acquired UTIs (defined as at least 10⁵ colony-forming units/ml of one or two organisms 48 hours or more after ICU admission) occurred among 290 (6.5%) patients, yielding an overall incidence density of ICU-acquired UTIs of 9.6 per 1000 ICU days. Four bacteremic/fungemic ICU-acquired UTIs occurred (0.1 per 1000 ICU days). Development of an ICU-acquired UTI was more common in women (relative risk [RR] 1.58; 95% confidence interval [CI] 1.43–1.75; P < 0.0001) and in medical (9%) compared with non-cardiac surgical (6%), and cardiac surgical patients (2%). The most common organisms isolated were Escherichia coli (23%), Candida albicans (20%), and Enterococcus species (15%). Antibiotic-resistant organisms were identified among 14% isolates. Although development of an ICU-acquired UTI was associated with significantly higher crude in-hospital mortality (86/290 [30%] vs. 862/4167 [21%]; RR = 1.43; 95% CI 1.19–1.73; P < 0.001); an ICU-acquired UTI was not an independent predictor for death.

Development of an ICU-acquired UTI is common in critically ill patients. Although a marker of increased morbidity associated with critical illness, it is not a significant attributable cause of mortality.