Hoberman A, Wald E R, Reynolds E A, Penchansky L, Charron M
Department of Pediatrics, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh, PA 15213.
J Pediatr. 1994 Apr;124(4):513-9. doi: 10.1016/s0022-3476(05)83127-0.
Results of urinalysis and culture of 2181 urine specimens obtained by catheter from febrile children aged less than 24 months were analyzed to determine the following: (1) an optimal cutoff point in considering a bacterial colony count clinically "significant," (2) the accuracy of leukocyte esterase and nitrite tests in identification of pyuria and bacteriuria, and (3) the utility of pyuria (defined as > or = 10 leukocytes/mm3) in the discrimination of urinary tract infection from asymptomatic bacteriuria. Among 110 urine cultures with > or = 10,000 colony-forming units per milliliter, 92 (84%) had > or = 100,000 CFU/ml, 10 (9%) had 50,000 to 99,000 CFU/CFU/ml and 8 (7%) had 10,000 to 49,000 CFU/ml. Urine specimens with 1000 to 49,000 CFU/ml were more likely than specimens with > or = 50,000 CFU/ml to yield Gram-positive or mixed organisms (36/60 vs 7/109; p < 0.001). A count of < 10 leukocytes/mm3 was almost invariably associated with a sterile culture; a count of > or = 10 leukocytes/mm3 was found in 93 of 102 patients with > or = 50,000 CFU/ml. The dipstick leukocyte esterase test had sensitivities of 52.9% and 66.7% in detecting > or = 10 leukocytes/mm3 and > or = 20 leukocytes/mm3, respectively. The dipstick nitrite test had a sensitivity of 31.4% in detecting bacteriuria (> or = 50,000 CFU/ml). Acute pyelonephritis was diagnosed by a renal scan with dimercaptosuccinic acid labeled with technetium 99m in 50 (77%) of 65 patients with > or = 10 leukocytes/mm3 but in none of five patients with < 10 leukocytes/mm3 (p < 0.01). The findings in these five patients were consistent with colonization of the urinary tract rather than infection. For urine specimens obtained by catheter, we believe that urinary tract infection is best defined by both a leukocyte count > or 10/mm3 and a CFU count > or = 50,000/ml. This definition almost always discriminates among true urinary tract infection, bacteriuria resulting from contamination of the urine specimen, and asymptomatic bacteriuria.
对2181份通过导尿术采集的24个月龄以下发热儿童的尿液标本进行尿液分析和培养，分析结果以确定以下几点：（1）临床上认为细菌菌落计数“有意义”的最佳临界值；（2）白细胞酯酶和亚硝酸盐试验在识别脓尿和菌尿方面的准确性；（3）脓尿（定义为≥10个白细胞/mm³）在区分尿路感染和无症状菌尿方面的作用。在每毫升菌落形成单位≥10000的110份尿培养物中，92份（84%）每毫升菌落形成单位≥100000，10份（9%）每毫升菌落形成单位为50000至99000，8份（7%）每毫升菌落形成单位为10000至49000。每毫升菌落形成单位为1000至49000的尿液标本比每毫升菌落形成单位≥50000的标本更有可能培养出革兰氏阳性菌或混合菌（36/60比7/109；p<0.001）。白细胞计数<10个/mm³几乎总是与无菌培养相关；在每毫升菌落形成单位≥50000的102例患者中，有93例白细胞计数≥10个/mm³。尿试纸白细胞酯酶试验在检测≥10个白细胞/mm³和≥20个白细胞/mm³时的敏感性分别为52.9%和66.7%。尿试纸亚硝酸盐试验在检测菌尿（每毫升菌落形成单位≥50000）时的敏感性为31.4%。65例白细胞计数≥10个/mm³的患者中，50例（77%）通过用99m锝标记的二巯基丁二酸进行肾扫描诊断为急性肾盂肾炎，但5例白细胞计数<10个/mm³的患者均未诊断为急性肾盂肾炎（p<0.01）。这5例患者的检查结果与尿路定植而非感染一致。对于通过导尿术采集的尿液标本，我们认为尿路感染的最佳定义是白细胞计数>或10/mm³且菌落形成单位计数≥50000/ml。这一定义几乎总能区分真正的尿路感染、因尿液标本污染导致的菌尿和无症状菌尿。
