Robertson A W, Duff P
Division of Maternal-Fetal Medicine, Madigan Army Medical Center, Tacoma, Washington.
Obstet Gynecol. 1988 Jun;71(6 Pt 1):878-81.
The purpose of this investigation was to compare the reliability of a urine dipstick evaluation for nitrites and leukocyte esterase activity with that of a urine culture in diagnosing asymptomatic bacteriuria in obstetric patients. A clean-catch midstream urine specimen was obtained from 750 consecutive obstetric patients presenting for initial evaluation. One portion of the specimen was tested for nitrites and leukocyte esterase activity with Chemstrip LN dipsticks. A second aliquot of urine was plated on blood and MacConkey agar and incubated aerobically. The cost of the nitrite and leukocyte esterase test was $0.35. The per patient charge for the urine cultures would have been $28. Sixty-two women (8.3%) had urine cultures of 100,000 or more colony-forming units of a uropathogen per milliliter. The sensitivities of the nitrite and leukocyte esterase test in identifying patients with positive cultures were 43 and 77%, respectively, and the specificities were 99 and 96%, respectively. The sensitivity and specificity for the two tests combined (either test abnormal) were 92 and 95%, respectively. Five patients had negative screening tests but positive urine cultures; all five isolates were gram-positive organisms, three group B streptococci and two enterococci. We conclude that neither the nitrite test nor the leukocyte esterase test alone is a sensitive enough screening test to detect asymptomatic bacteriuria in obstetric patients. The combination of the two tests, however, may provide an acceptable cost-effective alternative to screening all asymptomatic obstetric patients with urine cultures.
本研究的目的是比较尿试纸条检测亚硝酸盐和白细胞酯酶活性与尿培养在诊断产科患者无症状菌尿方面的可靠性。从750例前来进行初次评估的连续产科患者中获取清洁中段尿标本。将一部分标本用Chemstrip LN试纸条检测亚硝酸盐和白细胞酯酶活性。取另一等分尿液接种于血琼脂和麦康凯琼脂上，进行需氧培养。亚硝酸盐和白细胞酯酶检测的成本为0.35美元。尿培养每位患者的收费为28美元。62名女性（8.3%）每毫升尿培养中有100,000个或更多菌落形成单位的尿路致病菌。亚硝酸盐和白细胞酯酶检测在识别培养阳性患者中的敏感性分别为43%和77%，特异性分别为99%和96%。两项检测联合（任一检测异常）的敏感性和特异性分别为92%和95%。5例患者筛查试验阴性但尿培养阳性；所有5株分离菌均为革兰氏阳性菌，3株B族链球菌和2株肠球菌。我们得出结论，单独的亚硝酸盐检测或白细胞酯酶检测都不是足够敏感的筛查试验，无法检测产科患者的无症状菌尿。然而，两项检测联合可能为筛查所有无症状产科患者的尿培养提供一种可接受的成本效益替代方法。
