Evaluation of urine analysis by flow cytometry and strip test in diagnosing urinary tract infection / 中华检验医学杂志

ABSTRACT

Objective To evaluate the clinical application of automated urine formed elements analyzer and/or urine dipstick analyzer for examination of urinary formed elements in screening urinary tract infection (UTI). Methods 148 fresh midstream clear-catch urine samples from the UTI patients and 284 fresh midstream clear-catch urine samples from non-UTI subjects were selected. Bacteria culture was performed for bacterial colony counting and identification. Bacteria counts ( BACT), yeast-like fungus and WBC were performed by UF-looOi automated urine formed elements analyzer. Leukocyte esterase test (LEU) and nitrite test (NIT) were performed by URISYS 2400 urine dipstick analyzer. We evaluated data obtained from urine dipstick analyzer, UF-1000i and combination of UF-1000i with urine dipstick analyzer and the results was compared with those obtained from quantitative bacterial culture. Then we evaluated the sensibility, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy. Results Among the 148 patients with UTI, the positive rate of the quantitative bacterial culture was 73.6% (109/148), the positive rate of LEU and NIT detected by dipstick test 26. 4% (39/148).There was significantly statistical difference between bacterial culture and strip test(χ2 = 55.68 ,P < 0. 05 ). The positive rate of urine flow cytometry by UF-1000i with either positive of BACT and WBC was 91.2%(135/148), which was higher than the positive rate of the quantitative bacterial culture. There was significant difference between two methods (χ2 = 14. 70, P < 0. 05 ). The positive rate of anyone positive among BACT, WBC, LEU and NIT was 94. 6% (140/148) when detected with combination of dipstick test and UF-1000i, which was higher than the positive rate of the quantitative bacterial culture. And there was significant difference between two methods (χ2 = 20. 45, P < 0. 05 ). The sensitivity of dipstick test was low (26. 4% ,39/148 ), and specificity was high ( 99. 3%, 282/284 ) . The sensitivity, specificity, positive predictive value, negative predictive value of BACT detected by UF-1000i in diagnosing urinary tract infection were 92. 6% ( 137/148 ), 39. 8% ( 113/284 ). 44. 5% ( 137/308 ) and 91.1% ( 113/124 ), respectively. If the dipstick test was combined with UF-1000i, the sensitivity, negative predictive value, specificity, positive predictive value and accuracy were 98.0% ( 145/148 ), 97.1% ( 100/103 ). 35.2% (100/284) ,44. 1% (145/329) and 56. 7% (245/432), respectively. Conclusions The combination of urine dipstick test and automated urine formed elements analyzer UF-1000i plays an important role in early diagnosis of UTI. And it has significant value in diagnosis of UTI, especially for the patients with negative bacterial cultures of urine sample.