Unsatisfactory performance of the leukocyte esterase test of first voided urine for rapid diagnosis of urethritis.

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Abstract
BACKGROUND AND OBJECTIVES--The objective of this study was to determine the performance characteristics of a dipstick test for leukocyte esterase (LE), (Chemstrip 2LN, Boehringer Mannheim) in predicting the presence of urethritis and urethral pathogens in men presenting to a busy sexually transmitted disease clinic and to street outreach facilities. METHODS--Urethral swabs for polymorphonuclear (pmn) cell count, gonorrhoea culture and chlamydia enzyme immunoassay (EIA) as well as 15 ml of first voided urine (FVU) were collected from 737 symptomatic and 726 asymptomatic men. Gonorrhoea cultures and pmn counts were processed according to standard methods. Either Abbott Chlamydiazyme EIA (confirmed) or Syva Microtrak EIA (confirmed) test was employed to detect C trachomatis. The LE test was immediately dipped in FVU, read after 60-120 seconds by the clinician and considered positive if trace, 1+ or 2+. RESULTS--Microscopic evidence of urethritis (> or = = 4 pmn cells per 1000 x field) was found on urethral smear of 782 (53.5%) patients. Chlamydia, gonorrhoea or both were present in 104 (7.1%) patients. Performance characteristics of the LE test were as follows: (table below) CONCLUSION--The LE test did not have adequate sensitivity to be considered a reliable rapid diagnostic test for urethritis or urethral pathogens, particularly in the asymptomatic portion of this STD clinic population.