The Comparison of Microscopic Urine Sediment, Nitrite, and Leukocyte Esterase Tests for Bacteriuria

Shin, Bo Moon

Abstract

BACKGROUND: Although bacteriologic culture remains the gold standard for detecting bactriuria, leukocyte esterase, nitrite and urine microscopy are also widely used. However, it is not uncommon to be presented with a discrepancy between these tests.
METHODS
We performed leukocyte esterase and nitrite tests by urine reagent strip testing (Combur 10 Test, Roche, Germany), microscopic urinalysis, and by bacteriologic urine culture on 290 persons.
RESULTS
The number of pathogens and non-pathogens were 51 (17.6%) and 87 (30.0%) respectively. The number of cases in which no microorganism was isolated (NMI group) was 152 (52.4%). The concordance rate between leukocyte esterase and microscopic leukocytes (leukocyturia) was 70.7%. The sensitivities and specificities of leukocyte esterase, microscopic leukocyte and microscopic bacteria were 72.5%/61.8%, 76.5%/44.1 % and 80.4%/92.1% respectively, and their positive predictive values and negative predictive values were 24% (62.3%)/69.1% (89.7%), 21.3% (53.6%)/62.6% (88.8%) and 51.9% (84.8%)/66.4% (95.3%), respectively. Although the nitrite test showed higher positive rates in the pathogen groups (37.2%) than in the non-pathogen group (2.2%) and NMI group (1.3%), this was only marginally significant.
CONCLUSION
The microscopic estimation of bacteria is more a predictable marker of bacteriuria, rather than leukocyte esterase, nitrite, and microscopic leukocytes, in urine.