Dipstick leukocyte esterase activity in first-catch urine specimens. A useful screening test for detecting sexually transmitted disease in the adolescent male

Abstract

Although sexually active female adolescents are often routinely screened for sexually transmitted diseases, indications for culturing adolescent males for sexually transmitted urethral infections are controversial. A study of 54 sexually active males (14 to 22 years old) was undertaken to assess the reliability of using dipstick leukocyte esterase activity in first-catch urine specimens to detect urethritis caused by Neisseria gonorrhoeae and Chlamydia trachomatis. Eighteen males had sexually transmitted diseases: N gonorrhoeae (nine patients), C trachomatis (eight patients), and N gonorrhoeae and C trachomatis (one patient). First-catch urine specimens with a 1+ (mild) or 2+ (moderate) reaction on dipstick testing had a leukocyte (WBC) count of 10 WBCs per high-power field or greater on microscopic analysis, with an 83% sensitivity, 100% specificity, a 100% positive predictive value, and a 92% negative predictive value for the presence of N gonorrhoeae, C trachomatis, or both. Clinical criteria for screening (urethral discharge, dysuria, or exposure to a sexually transmitted infection) plus a dipstick-positive first-catch urine specimen had a 94% sensitivity, 89% specificity, an 81% positive predictive value, and a 97% negative predictive value.