Urinary interleukin-8 with asymptomatic bacteriuria in pregnancy.
OBJECTIVE
To evaluate urinary interleukin-8 (IL-8), an inflammatory cytokine, as a screening method for detecting asymptomatic bacteriuria in pregnancy.


METHODS
Clean-catch urine samples from 200 pregnant women undergoing screening for asymptomatic bacteriuria were evaluated by urine culture, urine dipstick analysis, and measurement of IL-8. Interleukin-8 levels were measured by a chemiluminescent immunoassay (Immulite IL-8, Diagnostic Products Corp., Los Angeles, CA), and a receiver operating characteristic curve was used to determine the optimal cutoff point. Asymptomatic bacteriuria was defined as at least 100,000 colony-forming units of a single organism per mL. Dipstick testing included nitrite assessment as positive or negative and leukocyte esterase as negative, trace, 1+, 2+, or 3+. Dipstick testing was considered positive if nitrite was positive or leukocyte esterase was trace or greater. Sensitivities, specificities, positive and negative predictive values 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 statistical analyses.


RESULTS
Twenty women were identified with asymptomatic bacteriuria by urine culture. The median urinary IL-8 levels for women with and without asymptomatic bacteriuria were 356 pg/mL and 125 pg/mL, respectively (P <.01, Mann-Whitney U test). Using an optimal cutoff point of 264 pg/mL, IL-8 had a sensitivity, specificity, positive and negative predictive value of 70%, 67%, 19%, and 95% for predicting asymptomatic bacteriuria. Urine dipstick analysis 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.


CONCLUSIONS
Urinary interleukin-8 is not an acceptable screening method for asymptomatic bacteriuria in pregnancy because it fails to detect 30% of women with this condition.
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Durham, North Carolina, USA. stuart.shelton@amedd.army.mil
S D
SD
Shelton
K A
KA
Boggess
K
K
Kirvan
F
F
Sedor
W N
WN
Herbert
D000328:Adult; D001437:Bacteriuria / Q000175:diagnosis*; D002265:Carboxylic Ester Hydrolases / Q000652:urine; D004926:Escherichia coli / Q000302:isolation & purification; D005260:Female; D006801:Humans; D016209:Interleukin-8 / Q000652:urine*; D008163:Luminescent Measurements; D009573:Nitrites / Q000652:urine; D011237:Predictive Value of Tests; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis*; D012680:Sensitivity and Specificity
D016209:Interleukin-8; D009573:Nitrites; C021443:leukocyte esterase; D002265:Carboxylic Ester Hydrolases