Clinical Implications of ICU-Acquired Urinary Tract Infection

Abstract & Commentary

David J. Pierson, MD, Pulmonary and Critical Care Medicine, Harborview Medical Center, University of Washington, is Editor for Critical Care Alert.

Synopsis: This 3-year cohort surveillance study of all adult patients admitted to ICUs in one region found that they were common (developing in 6.5% of patients, or 9.6 UTIs per 1000 ICU days) but did not contribute independently to mortality.

Source: Laupland KB, et al. Crit Care. 2005;9:R60-R65. http://ccforum.com/content/9/2/R60. Accessed March 15, 2005.

Laupland and colleagues at the University of Calgary performed a surveillance cohort study of ICU-acquired urinary tract infections (UTIs) in all adult multisystem and cardiovascular surgery ICUs in the Calgary Health Region, an area with approximately 1 million inhabitants. All patients aged 18 or older who remained in the ICU for more than 48 hours were included. ICU-acquired UTI was defined as a positive urine culture (at least 100,000 colony-forming units per mL) obtained at least 48 hours after ICU admission or during the last 48 hours prior to ICU discharge. Patients with and without ICU-acquired UTI were compared for demographics, in-hospital mortality, and severity of illness as assessed by APACHE II and TISS scores.

During the 3-year surveillance period, 4465 patients were admitted to the study ICUs for at least 48 hours, for a total of 4915 ICU stays, ICU-acquired UTIs occurred in 290 (6.5%) patients, or 9.6 UTIs per 1000 ICU days. UTIs were more common in women (174/1755 vs 116/2709; relative risk 1.58; 95% CI, 1.43-1.75; P < 0.0001), and in medical as compared to cardiovascular, and noncardiovascular surgical patients. The incidence of UTI increased with increasing lengths of ICU and hospital stay, but not with increasing APACHE II or TISS scores. There were only 4 instances of bacteremia or fungemia among patients acquiring a UTI in the ICU (0.1 per 1000 ICU days). The most commonly isolated organisms were Escherichia coli (23%), Candida albicans (20%), and Enterococcus species (15%). In-hospital mortality correlated with APACHE II score, length of stay, and admission to services other than medicine, but not with the acquisition of a UTI in the ICU.

COMMENT BY DAVID J. PIERSON, MD

This study extends Laupland et al’s previous work on the incidence and characteristics of ICU-acquired UTI, using a larger and more all-inclusive patient population. It shows that UTI develops more frequently the longer patients remain in the ICU, but does not appear to increase the likelihood of death as an independent risk factor. Unlike previous studies of this issue, the investigation of Laupland et al was adequately powered to detect such an increase. Although the crude mortality risk was higher, once confounding by measures of severity of illness, diagnostic category, and length of ICU stay were controlled for, ICU-acquired UTI was not independently associated with death.