Rapid screening and microbiologic processing of pediatric urine specimens

Urinary nitrite and leukocyte esterase dipstick tests were evaluated as rapid screening procedures to select probable culture-positive urines for direct identification (AutoMicrobic System urine cards) and modified Kirby-Bauer susceptibility testing. Approximately 73% of significant culture-positive (〉 10 5 organisms per milliliter, pure culture) urine specimens could be selected by nitrite testing alone with very high specificity (∼99%). The leukocyte esterase test detected 85% of culture-positive urines when used alone and ∼91% when used in combination with nitrite testing (if either test was positive it was considered a positive screening); however, the esterase test was significantly less specific for bacteriuria than the nitrite test. Based on these results, the nitrite test was selected for use as the screening test. Rapid, direct identification and susceptibility tests on screen-positive urines showed 97% correlation with standard testing methods. Significant positive urines processed in this manner could be reported with quantitation, identification, and susceptibility results within 24 hr.