Laboratory evaluation of leukocyte esterase and nitrite tests for the detection of bacteriuria

Abstract

We compared the sensitivity, specificity, and predictive values of the 1-min leukocyte esterase test and the test for urinary nitrite alone and in combination as screening tests for bacteriuria in over 5,000 clinical urine specimens. The leukocyte esterase-nitrite combination had a sensitivity of 79.2%, a specificity of 81%, and a negative predictive value of a negative test of 94.5% for specimens with 2105 CFU/ml. Although the sensitivity of this test was too low to allow its use as the only screening test for bacteriuria, it may serve as a useful adjunct to culturing and other urine-processing systems in the microbiology laboratory.

Field evaluation of a second-generation cytometer UF-100 in diagnosis of acute urinary tract infections in adult patients

“…There were 171 (8.51%) false-negative results and 184 (9.15%) false-positive results. In our experience the dipstick screening SE was 0.64, SP was 0.88, PPV was 0.63, NPV was 0.89 and CCI was 0.82; these results appeared to be in good accordance with data from the literature [5][6][7][11][12][13]. Quanti-tative determination of bacteriuria and pyuria by UF-100 showed 29 (1.44%) false-negative results and 102 (5.07%) false-positive results.…”

Accuracy of urinalysis in detection of urinary tract infection in a primary care setting

“…The NIT test is the most specific in urine dipstick (82%). This finding is also supported by Seminiuk and Church, Jones et al and Pfaller and Koontz who also found NIT test had the highest specificity (97, 98.6, 97.2%, respectively) 11,18,19 . Winkens et al .…”

“…Combination of any two or even three positive tests will increase the sensitivity but will decrease the specificity. Most of the studies have similar findings 18,19 . A negative result, when combining two or three tests produces a higher negative predictive value (90% each).…”

“…This finding is comparable with studies done by Seminiuk and Church, Jones et al . and Pfaller and Koontz where LE test is more sensitive than NIT test 11,18,19 . Winkens et al .…”

A European perspective on nosocomial urinary tract infections I. Report on the microbiology workload, etiology and antimicrobial susceptibility (ESGNI–003 study)

“…Only 19% of hospitals use screening criteria either to select urine for culture or to complete the culture results, with a trend towards more screening in EU countries. Such procedures include pyuria detection [11], dipstrips for nitrites and leukocyte esterase [12,13], microscopy and, more recently, automated systems for bacteriuria and pyuria detection [14][15][16][17][18][19][20][21][22][23][24][25]. The questionnaire data showed a wide range of cut-off values to define clinically significant bacteriuria in the different laboratories and countries.…”