尿干化学分析和涂片镜检在筛选尿路感染中的应用

Application of urine dipstick and smear Gram-staining microscopic examination tests in screening of urinary tract infection

目的 比较尿干化学分析中白细胞酯酶、亚硝酸盐试验和涂片染色镜检在筛选泌尿系统感染中的可靠性。方法 收集 4 0 0份合格中段尿标本 ,先取 10 μl做细菌培养及菌落计数 ,剩余标本做干化学分析及涂片染色镜检。结果 有 4 1例培养出有意义细菌 (菌落计数≥ 10 5cfu/ml) ,占 10 .3%。白细胞酯酶和亚硝酸盐试验的敏感性分别为 73.2 %、4 6 .3% ,特异性分别为 86 .6 %、98.1% ,两者合并敏感性、特异性分别为 90 .2 %、85 .2 %。另外有 4例 (9.5 % )标本培养阳性但干化学分析阴性。镜检共有 30例阳性 ,敏感性 6 1.36 % (2 7/ 4 1) ,其中 3例镜检阳性但培养阴性。若以菌落计数≥ 10 4cfu/ml为标准 ,则阳性例数达到 5 5例 (占 13.8% ) ,干化学分析的敏感性、特异性及阴性预示值 (NPV)变化不大 ,但阳性预示值 (PPV)却显著提高 ;涂片染色镜检的特异性稍有降低 ,但镜检PPV却不变。结论 尿试条干化学分析、涂片染色镜检在筛选泌尿系统感染时敏感性不足 。

Objective To compare the reliability of a urine dipstick evaluation for leukocyte esterase(LE) and nitrite (NIT) activity and smear Gram staining microscopic examination with the urine culture in diagnosing urinary tract infection (UTI). Methods 10 μl of clean catch midstream urine specimen was examined by culture, the other portion was tested with dipstick for presence of LE, NIT and for smear Gram staining microscopic examination. Results In 400 patients, 41(10.3%) showed culture positive. Comparing to the culture examination, the sensitivities of LE and NIT were 73.2% and 46.3% respectively, and the specificities were 86.6% and 98.1% respectively. The sensitivity and speciticity for the two tests combined were 90.2% and 85.2% respectively. The sensitivity of microscopic examination was 61.36%. Conclusions Urine dipstick test and smear Gram staining microscopic examination are not sufficiently sensitive to be used in the screening for UTI. Bacteriuria culture must be done in diagnosing UTI.