Urinary Squamous Epithelial Cells Do Not Accurately Predict Urine Culture Contamination, but May Predict Urinalysis Performance in Predicting Bacteriuria

Nicholas M Mohr; Karisa K Harland; Victoria Crabb; Rachel Mutnick; David Baumgartner; Stephanie Spinosi; Michael Haarstad; Azeemuddin Ahmed; Marin Schweizer; Brett Faine

doi:10.1111/acem.12894

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Urinary Squamous Epithelial Cells Do Not Accurately Predict Urine Culture Contamination, but May Predict Urinalysis Performance in Predicting Bacteriuria

Journal article

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Urinary Squamous Epithelial Cells Do Not Accurately Predict Urine Culture Contamination, but May Predict Urinalysis Performance in Predicting Bacteriuria

Nicholas M Mohr, Karisa K Harland, Victoria Crabb, Rachel Mutnick, David Baumgartner, Stephanie Spinosi, Michael Haarstad, Azeemuddin Ahmed, Marin Schweizer and Brett Faine

Academic emergency medicine, Vol.23(3), pp.323-330

03/2016

DOI: 10.1111/acem.12894

PMID: 26782662

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Abstract

The presence of squamous epithelial cells (SECs) has been advocated to identify urinary contamination despite a paucity of evidence supporting this practice. We sought to determine the value of using quantitative SECs as a predictor of urinalysis contamination. Retrospective cross-sectional study of adults (≥18 years old) presenting to a tertiary academic medical center who had urinalysis with microscopy and urine culture performed. Patients with missing or implausible demographic data were excluded (2.5% of total sample). The primary analysis aimed to determine an SEC threshold that predicted urine culture contamination using receiver operating characteristics (ROC) curve analysis. The a priori secondary analysis explored how demographic variables (age, sex, body mass index) may modify the SEC test performance and whether SECs impacted traditional urinalysis indicators of bacteriuria. A total of 19,328 records were included. ROC curve analysis demonstrated that SEC count was a poor predictor of urine culture contamination (area under the ROC curve = 0.680, 95% confidence interval [CI] = 0.671 to 0.689). In secondary analysis, the positive likelihood ratio (LR+) of predicting bacteriuria via urinalysis among noncontaminated specimens was 4.98 (95% CI = 4.59 to 5.40) in the absence of SECs, but the LR+ fell to 2.35 (95% CI = 2.17 to 2.54) for samples with more than 8 SECs/low-powered field (lpf). In an independent validation cohort, urinalysis samples with fewer than 8 SECs/lpf predicted bacteriuria better (sensitivity = 75%, specificity = 84%) than samples with more than 8 SECs/lpf (sensitivity = 86%, specificity = 70%; diagnostic odds ratio = 17.5 [14.9 to 20.7] vs. 8.7 [7.3 to 10.5]). Squamous epithelial cells are a poor predictor of urine culture contamination, but may predict poor predictive performance of traditional urinalysis measures.

Body Mass Index

Urinary Tract Infections - diagnosis

Age Factors

Cross-Sectional Studies

Urine - cytology

Humans

Middle Aged

Male

Urinalysis - standards

Academic Medical Centers

Sensitivity and Specificity

Sex Factors

Adult

Bacteriological Techniques

Female

ROC Curve

Aged

Retrospective Studies

Epithelial Cells - cytology

Urine - microbiology

Details

Title: Subtitle: Urinary Squamous Epithelial Cells Do Not Accurately Predict Urine Culture Contamination, but May Predict Urinalysis Performance in Predicting Bacteriuria
Creators: Nicholas M Mohr - Division of Critical Care, Department of Anesthesia, University of Iowa Carver College of Medicine, Iowa City, IA
Karisa K Harland - Department of Emergency Medicine, University of Iowa Carver College of Medicine, Iowa City, IA
Victoria Crabb - Department of Epidemiology, University of Iowa College of Public Health, Iowa City, IA
Rachel Mutnick - Department of Emergency Medicine, University of Iowa Carver College of Medicine, Iowa City, IA
David Baumgartner - Department of Emergency Medicine, University of Iowa Carver College of Medicine, Iowa City, IA
Stephanie Spinosi - Department of Emergency Medicine, University of Iowa Carver College of Medicine, Iowa City, IA
Michael Haarstad - Department of Emergency Medicine, University of Iowa Carver College of Medicine, Iowa City, IA
Azeemuddin Ahmed - Department of Emergency Medicine, University of Iowa Carver College of Medicine, Iowa City, IA
Marin Schweizer - Iowa City Veterans Administration Health Care System, Iowa City, IA
Brett Faine - Department of Pharmaceutical Care, University of Iowa Hospitals and Clinics, Iowa City, IA
Resource Type: Journal article
Publication Details: Academic emergency medicine, Vol.23(3), pp.323-330
DOI: 10.1111/acem.12894
PMID: 26782662
NLM abbreviation: Acad Emerg Med
ISSN: 1069-6563
eISSN: 1553-2712
Publisher: United States
Grant note: DOI: 10.13039/100002076, name: Emergency Medicine Foundation
Language: English
Date published: 03/2016
Academic Unit: Management and Entrepreneurship ; Epidemiology; Emergency Medicine; Pharmacy Practice and Science; Anesthesia; Injury Prevention Research Center; Public Policy Center (Archive); General Internal Medicine; Law Faculty; Internal Medicine
Record Identifier: 9984024539902771

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