Urinary interleukin-8 with asymptomatic bacteriuria in pregnancy

Objective: To evaluate urinary interleukin-8 (IL-8), an inflammatory cytoki ne, as a screening method for detecting asymptomatic bacteriuria in pregnan cy. Methods: Clean-catch urine samples from 200 pregnant women undergoing scree ning for asymptomatic bacteriuria were evaluated by urine culture, urine di pstick analysis, and measurement of IL-8. Interleukin-8 levels were measure d by a chemiluminescent immunoassay (Immulite IL-8, Diagnostic Products Cor p., Los Angeles, CA), and a receiver operating characteristic curve was use d to determine the optimal cutoff point. Asymptomatic bacteriuria was defin ed as at least 100,000 colony-forming units of a single organism per mL. Di pstick testing included nitrite assessment as positive or negative and leuk ocyte esterase as negative, trace, 1+, 2+, or 3+. Dipstick testing was cons idered positive if nitrite was positive or leukocyte esterase was trace or greater. Sensitivities, specificities, positive and negative predictive val ues were determined for urinary leukocyte esterase and nitrite and compared with those of IL-8. chi (2) and Mann-Whitney U tests were used for statist ical analyses. Results: Twenty women were identified with asymptomatic bacteriuria by urin e culture. The median urinary IL-8 levels for women with and without asympt omatic bacteriuria were 356 pg/mL and 125 pg/mL, respectively (P < .01, Man n-Whitney U test). Using an optimal cutoff point of 264 pg/mL, IL-8 had a s ensitivity, specificity, positive and negative predictive value of 70%, 67% , 19%, and 95% for predicting asymptomatic bacteriuria. Urine dipstick anal ysis with either a positive leukocyte esterase or nitrite had a sensitivity , specificity, positive and negative predictive value of 45%, 62%, 12%, and 91%, respectively, for detecting asymptomatic bacteriuria. The differences between these testing methods were not statistically significant. Conclusion: Urinary interleukin-8 is not an acceptable screening method for asymptomatic bacteriuria in pregnancy because it fails to detect 30% of wo men with this condition. <(c)> 2001 by The American College of Obstetrician s and Gynecologists.