Disappointing dipstick screening for urinary tract infection in hospital inpatients.
OBJECTIVE
To compare the performance of leucocyte esterase and nitrite dipstick tests with microscopic examination and culture of first morning urines (n = 420) of hospital inpatients.


RESULTS
The sensitivity, specificity, and negative predictive value of the leucocyte esterase test for the cutoff of > 10 WBC/microliter were 57%, 94%, and 68%, respectively. For > 5 WBC per high power field (HPF) these variables were 84%, 90%, and 93%. For > 10(5) colony counts/ml, the sensitivity of the nitrite test was 27%, specificity 94%, and negative predictive value 87%. When either leucocyte esterase or nitrite positivity was accepted as a marker of urinary tract infection, the sensitivity was 78%, specificity 75%, and negative predictive value 94%, and there were 22% false negative results. Semiquantitative microscopic estimation of bacteria per HPF yielded 40% false positives.


CONCLUSIONS
Leucocyte esterase and nitrite dipstick tests are not suitable for screening for urinary tract infections.
University Hospitals Leuven, Belgium Central Clinical Laboratory, Belgium. zahur.zaman@uz.kuleuven.ac.be
Z
Z
Zaman
A
A
Borremans
J
J
Verhaegen
L
L
Verbist
N
N
Blanckaert
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001431:Bacteriological Techniques; D015415:Biomarkers / Q000652:urine; D002265:Carboxylic Ester Hydrolases / Q000652:urine*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000201:enzymology; D009573:Nitrites / Q000652:urine*; D011237:Predictive Value of Tests; D011934:Reagent Strips; D012680:Sensitivity and Specificity; D014552:Urinary Tract Infections / Q000175:diagnosis* / Q000382:microbiology
D015415:Biomarkers; D009573:Nitrites; D011934:Reagent Strips; C021443:leukocyte esterase; D002265:Carboxylic Ester Hydrolases