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Published on: October 15, 2014
Cost and Utility of Microbiological Cultures Early After Intensive Care Unit Admission for Intracerebral Hemorrhage
Jonathan Elmer1, David Yamane2, Peter C Hou3,4
1Departments of Emergency Medicine and Critical Care Medicine, University of Pittsburgh, Iroquois Building, Suite 400A, 3600 Forbes Avenue, Pittsburgh, PA, 15213, USA. elmerp@upmc.edu.
Background:
Fever is common among intensive care unit (ICU) patients. Clinicians may use microbiological cultures to differentiate infectious and aseptic fever. However, their utility depends on the prevalence of infection; and false-positive results might adversely affect patient care. We sought to quantify the cost and utility of microbiological cultures in a cohort of ICU patients with spontaneous intracerebral hemorrhage (ICH).
Methods:
We performed a secondary analysis of a cohort with spontaneous ICH requiring mechanical ventilation. We collected baseline data, measures of systemic inflammation, microbiological culture results for the first 48 h, and daily antibiotic usage. Two physicians adjudicated true-positive and false-positive culture results using standard criteria. We calculated the cost per true-positive result and used logistic regression to test the association between false-positive results with subsequent antibiotic exposure.
Results:
Overall, 697 subjects were included. A total of 233 subjects had 432 blood cultures obtained, with one true-positive (diagnostic yield 0.1 %, $22,200 per true-positive) and 11 false-positives. True-positive urine cultures (5 %) and sputum cultures (13 %) were more common but so were false-positives (6 and 17 %, respectively). In adjusted analysis, false-positive blood and sputum results were associated with increased antibiotic exposure.
Conclusions:
The yield of blood cultures early after spontaneous ICH was very low. False-positive results significantly increased the odds of antibiotic exposure. Our results support limiting the use of blood cultures in the first two days after ICU admission for spontaneous ICH.
Insights
Microbiological cultures in intensive care unit (ICU) patients with spontaneous intracerebral hemorrhage (ICH) have low diagnostic yield. Limiting early blood cultures in ICH patients can reduce unnecessary antibiotic exposure from false-positive results.
Area of Science:
- Critical Care Medicine
- Infectious Diseases
- Neurology
Background:
- Fever is common in intensive care unit (ICU) patients, often necessitating differentiation between infectious and aseptic causes.
- Microbiological cultures are used to identify infections, but their utility is influenced by infection prevalence and risk of false-positive results.
- The cost and utility of microbiological cultures in spontaneous intracerebral hemorrhage (ICH) patients require quantification.
Purpose of the Study:
- To quantify the cost and diagnostic utility of microbiological cultures within the first 48 hours of ICU admission for patients with spontaneous intracerebral hemorrhage (ICH).
- To assess the association between false-positive culture results and subsequent antibiotic exposure in this patient cohort.
Main Methods:
- Secondary analysis of a cohort of spontaneous ICH patients requiring mechanical ventilation.
- Collection of baseline data, systemic inflammation markers, microbiological cultures (blood, urine, sputum) within 48 hours, and daily antibiotic usage.
- Adjudication of true-positive and false-positive results by two physicians, cost-per-true-positive calculation, and logistic regression for association analysis.
Main Results:
- One true-positive blood culture (0.1% yield, $22,200 cost per true-positive) and 11 false-positives were identified among 432 blood cultures.
- True-positive rates for urine (5%) and sputum (13%) cultures were higher, but so were false-positive rates (6% and 17%, respectively).
- False-positive results for blood and sputum cultures were significantly associated with increased antibiotic exposure.
Conclusions:
- Early microbiological cultures, particularly blood cultures, demonstrate very low diagnostic yield in spontaneous ICH patients.
- False-positive results from these cultures significantly increase the likelihood of antibiotic exposure.
- Limiting the use of blood cultures in the initial 48 hours for spontaneous ICH patients is recommended to optimize patient care and resource utilization.
