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Squamous epithelial cell presence reduces accuracy of urinalysis for prediction of positive urine cultures.
Am J Emerg Med. 2020 07; 38(7):1384-1388.AJ

Abstract

BACKGROUND

Diagnostic value of urinalysis specimens contaminated with squamous epithelial cells (SEC) from the genital surfaces is assumed to be limited compared to clean-catch samples. However, no studies have quantified the change in predictive value in the presence of SECs for individual urinalysis markers.

METHODS

In a retrospective, single center cohort study, we analyzed all urine cultures sent from the ED over a 26-month period with corresponding urinalysis results. Cultures were classified as positive with growth of >104 colony forming units of pathogenic bacteria, negative if no growth, or contaminated for all other results. UA specimens were classified as contaminated or clean based on SEC presence. Accuracy of urinalysis markers for prediction of positive cultures was calculated as an area under the curve (AUC) and was compared between contaminated and clean UA specimens.

RESULTS

6490 paired UA and urine cultures were analyzed, consisting of 3949 clean and 2541 contaminated samples. SEC presence was less common with male gender, older age, and smaller BMI. Urine cultures were 19.2% positive overall, and SECs were more common in contaminated cultures. AUCs for individual markers ranged from 0.557 to 0.796, with pyuria, bacteriuria, and leukocyte esterase having higher AUC in clean samples over contaminated.

CONCLUSION

Analysis of AUC for individual urinalysis markers showed reduced diagnostic accuracy in the presence of SECs. SEC presence also reflected much higher rates of contaminated cultures. These results support the reduced reliance on contaminated UA specimens for ruling in UTI in ED patients.

Authors+Show Affiliations

Department of Emergency Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States. Electronic address: patrick.maher@mountsinai.org.Department of Emergency Medicine, University of Washington School of Medicine and Harborview Medical Center, Seattle, WA, United States.Department of Emergency Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States.

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

31843330

Citation

Maher, Patrick J., et al. "Squamous Epithelial Cell Presence Reduces Accuracy of Urinalysis for Prediction of Positive Urine Cultures." The American Journal of Emergency Medicine, vol. 38, no. 7, 2020, pp. 1384-1388.
Maher PJ, Jablonowski KD, Richardson LD. Squamous epithelial cell presence reduces accuracy of urinalysis for prediction of positive urine cultures. Am J Emerg Med. 2020;38(7):1384-1388.
Maher, P. J., Jablonowski, K. D., & Richardson, L. D. (2020). Squamous epithelial cell presence reduces accuracy of urinalysis for prediction of positive urine cultures. The American Journal of Emergency Medicine, 38(7), 1384-1388. https://doi.org/10.1016/j.ajem.2019.11.024
Maher PJ, Jablonowski KD, Richardson LD. Squamous Epithelial Cell Presence Reduces Accuracy of Urinalysis for Prediction of Positive Urine Cultures. Am J Emerg Med. 2020;38(7):1384-1388. PubMed PMID: 31843330.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Squamous epithelial cell presence reduces accuracy of urinalysis for prediction of positive urine cultures. AU - Maher,Patrick J, AU - Jablonowski,Karl D, AU - Richardson,Lynne D, Y1 - 2019/11/28/ PY - 2019/09/29/received PY - 2019/11/13/revised PY - 2019/11/14/accepted PY - 2019/12/18/pubmed PY - 2020/8/25/medline PY - 2019/12/18/entrez SP - 1384 EP - 1388 JF - The American journal of emergency medicine JO - Am J Emerg Med VL - 38 IS - 7 N2 - BACKGROUND: Diagnostic value of urinalysis specimens contaminated with squamous epithelial cells (SEC) from the genital surfaces is assumed to be limited compared to clean-catch samples. However, no studies have quantified the change in predictive value in the presence of SECs for individual urinalysis markers. METHODS: In a retrospective, single center cohort study, we analyzed all urine cultures sent from the ED over a 26-month period with corresponding urinalysis results. Cultures were classified as positive with growth of >104 colony forming units of pathogenic bacteria, negative if no growth, or contaminated for all other results. UA specimens were classified as contaminated or clean based on SEC presence. Accuracy of urinalysis markers for prediction of positive cultures was calculated as an area under the curve (AUC) and was compared between contaminated and clean UA specimens. RESULTS: 6490 paired UA and urine cultures were analyzed, consisting of 3949 clean and 2541 contaminated samples. SEC presence was less common with male gender, older age, and smaller BMI. Urine cultures were 19.2% positive overall, and SECs were more common in contaminated cultures. AUCs for individual markers ranged from 0.557 to 0.796, with pyuria, bacteriuria, and leukocyte esterase having higher AUC in clean samples over contaminated. CONCLUSION: Analysis of AUC for individual urinalysis markers showed reduced diagnostic accuracy in the presence of SECs. SEC presence also reflected much higher rates of contaminated cultures. These results support the reduced reliance on contaminated UA specimens for ruling in UTI in ED patients. SN - 1532-8171 UR - https://www.unboundmedicine.com/medline/citation/31843330/Squamous_epithelial_cell_presence_reduces_accuracy_of_urinalysis_for_prediction_of_positive_urine_cultures_ DB - PRIME DP - Unbound Medicine ER -