Swenson Cheryl L, Boisvert Agatha M, Gibbons-Burgener Suzanne N, Kruger John M
Department of Pathobiology and Diagnostic Investigation and Diagnostic Center for Population and Animal Health, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA.
Vet Clin Pathol. 2011 Jun;40(2):256-64. doi: 10.1111/j.1939-165X.2011.00314.x. Epub 2011 May 9.
Urinary sediment examination and quantitative urinary culture results are frequently discordant.
The aims of this study were to compare accuracy of light microscopic examination of wet-mounted unstained (wet-unstained) and air-dried modified Wright-stained (dry-stained) sedimented preparations of urine with results of quantitative aerobic bacterial culture for detection and characterization of bacteriuria in cats. In addition, the presence of pyuria detected by urinalysis and potential risk factors were assessed.
A blinded prospective study was conducted on 472 urinary samples collected from 410 cats by cystocentesis. The age and sex of each cat were recorded. Complete urinalyses were performed and included quantification of WBCs. Quantity and morphology of bacteria in each specimen were determined by light microscopic examination of wet-unstained (performed by certified medical technologists) and dry-stained (performed by a veterinary clinical pathologist) sedimented preparations of urine and compared with results of quantitative bacterial cultures.
Of 472 urinary specimens, 29 were positive for bacteriuria by culture and considered true positives and 443 were considered true negatives. Compared with these results, examination of wet-unstained and dry-stained urines had sensitivities of 75.9% and 82.8%, specificities of 56.7% and 98.7%, and test efficiencies of 57.8% and 97.7%, respectively. Positive likelihood ratios were 1.8 and 63.7 and negative likelihood ratios were 0.42 and 0.17 for wet-unstained and dry-stained examinations, respectively. Compared with 29 culture-positive samples, the wet-unstained method had morphologic concordance and misclassification rates of 37.9% and 62.1%, respectively, whereas the dry-stained method had morphologic concordance and misclassification rates of 65.5% and 34.5%, respectively. Only 34% of samples with bacteriuria had pyuria. Frequency of bacteriuria was not significantly different based on age and sex of the cats, but there was a tendency for increased frequency in female cats and in cats >10 years old.
Staining dried urinary sediment with a modified Wright-stain significantly improved sensitivity, specificity, and test efficiency of microscopic detection and classification of bacteriuria compared with the wet-unstained method. Pyuria should not be a criterion for determining the presence or absence of bacteriuria.
尿沉渣检查结果与尿定量培养结果常常不一致。
本研究旨在比较未染色湿片（湿未染色）和空气干燥改良瑞氏染色（干染色）尿沉渣涂片的光学显微镜检查结果与需氧菌定量培养结果，以检测和鉴定猫的菌尿症。此外，评估通过尿液分析检测到的脓尿的存在情况及潜在风险因素。
对通过膀胱穿刺术从410只猫收集的472份尿液样本进行了一项盲法前瞻性研究。记录每只猫的年龄和性别。进行了完整的尿液分析，包括白细胞定量。通过未染色湿片（由认证医学技术人员操作）和干染色（由兽医临床病理学家操作）尿沉渣涂片的光学显微镜检查确定每个样本中细菌的数量和形态，并与细菌定量培养结果进行比较。
在472份尿液样本中，29份培养结果为菌尿阳性，被视为真阳性，443份被视为真阴性。与这些结果相比，未染色湿片和干染色尿液检查的敏感性分别为75.9%和82.8%，特异性分别为56.7%和98.7%，检测效率分别为57.8%和97.7%。未染色湿片和干染色检查的阳性似然比分别为1.8和63.7，阴性似然比分别为0.42和0.17。与29份培养阳性样本相比，未染色湿片法的形态一致性和错误分类率分别为37.9%和62.1%，而干染色法的形态一致性和错误分类率分别为65.5%和34.5%。只有34%的菌尿样本有脓尿。根据猫的年龄和性别，菌尿症的发生率没有显著差异，但雌性猫和10岁以上的猫有增加的趋势。
与未染色湿片法相比，用改良瑞氏染色干燥尿沉渣显著提高了显微镜检测和分类菌尿症的敏感性、特异性和检测效率。脓尿不应作为判断菌尿症是否存在的标准。
