Quantitative determination of leukocyte esterase with a paper-based device

Area of Science:

• Analytical Chemistry
• Biomedical Engineering
• Point-of-Care Diagnostics

Background:

• Commercially available urine dipsticks for urinary tract infection (UTI) detection have limitations in accurately quantifying leukocyte esterase (LE).
• The quantitative determination of urinary LE for predicting UTI remains uncertain, necessitating improved diagnostic tools.

Purpose of the Study:

• To develop and validate a paper-based analytical device for the quantitative point-of-care detection of LE (LE-PAD).
• To assess the diagnostic performance of the LE-PAD for early UTI detection in inpatients.

Main Methods:

• Fabrication of the LE-PAD using a coating of mixed 3-(N-tosyl-L-alaninyloxy)-5-phenylpyrrole (PE) and 1-diazo-2-naphthol-4-sulfonic acid (DAS) on a silver conducting film.
• Quantitative analysis of LE in urine samples from 21 inpatients with urinary catheters by measuring changes in resistivity.
• Establishment of a quantitative calibration curve and evaluation of diagnostic accuracy using receiver operating characteristic (ROC) analysis.

Main Results:

• The LE-PAD demonstrated a strong predictive value for UTI diagnosis, with an area under the ROC curve of 0.875.
• At an optimal cut-off, the LE-PAD achieved a sensitivity of 87.5% and specificity of 92.3% for UTI diagnosis.
• Compared to standard urine dipsticks (sensitivity 62.5%, specificity 76.9%), the LE-PAD showed significantly higher diagnostic accuracy.

Conclusions:

• The developed LE-PAD is a reliable and quantitative point-of-care test for detecting urinary LE.
• The LE-PAD offers superior diagnostic performance for UTI compared to conventional urine dipsticks.
• This novel device holds promise for improving early UTI detection and management.