1Veterinary Health Center, Kansas State University, Manhattan, KS.
2MiraVista Diagnostics, Indianapolis, IN.
J Am Vet Med Assoc. 2024 Jun 7;262(9):1-6. doi: 10.2460/javma.24.03.0220. Print 2024 Sep 1.
To determine the sensitivity and specificity of a commercial whole blood real-time PCR assay (RT-PCR) for the diagnosis of histoplasmosis when compared to direct organism identification and/or urine antigen quantification by enzyme immunoassay (UA-EIA). A secondary objective was to compare the sensitivity and specificity of RT-PCR to anti-Histoplasma immunoglobulin G antibody detection by enzyme immunoassay (IgG-EIA) and IgG-EIA to UA-EIA.
Cats presented to the Kansas State University Veterinary Health Center from February through September of 2023 in which histoplasmosis was diagnosed or suspected.
From February through September of 2023, cats were tested by RT-PCR, IgG-EIA, and UA-EIA if histoplasmosis was diagnosed cytologically or was a differential diagnosis for the presenting clinical signs. Cats were excluded if all 3 tests were not submitted or if the diagnosis of histoplasmosis could not be excluded despite a negative UA-EIA result. Cats with cytologically or histologically confirmed histoplasmosis were designated as proven histoplasmosis cases, and cats with a positive UA-EIA result without cytological or histological confirmation were designated as probable histoplasmosis cases.
10 cats were diagnosed with either proven (n = 6) or probable (4) histoplasmosis, and 10 cats were considered true negatives. Whole blood RT-PCR results were negative in all 20 cats (sensitivity, 0%; 95% CI, 0% to 30.85%). The IgG-EIA was 90% sensitive (95% CI, 55.50% to 99.75%) and 70% specific (95% CI, 34.75% to 93.33%). The UA-EIA results were positive in all cats with proven histoplasmosis.
This commercial RT-PCR is insensitive when used on whole blood collected in EDTA and should not be used to diagnose feline histoplasmosis. Further studies are required to determine whether alternate RT-PCR protocols for EDTA-collected whole blood could be useful for diagnosing histoplasmosis in cats.
当与直接的病原体鉴定和/或尿液抗原定量酶免疫测定（UA-EIA）相比时，确定一种商用全血实时 PCR 检测（RT-PCR）诊断组织胞浆菌病的敏感性和特异性。次要目标是比较 RT-PCR 与酶免疫测定（IgG-EIA）抗组织胞浆菌 IgG 抗体检测以及 IgG-EIA 与 UA-EIA 的敏感性和特异性。
2023 年 2 月至 9 月期间，因诊断或疑似组织胞浆菌病而被送往堪萨斯州立大学兽医健康中心的猫。
2023 年 2 月至 9 月期间，如果猫的细胞学检查诊断为组织胞浆菌病或为现有临床症状的鉴别诊断，将对其进行 RT-PCR、IgG-EIA 和 UA-EIA 检测。如果未提交所有 3 种检测结果，或者尽管 UA-EIA 结果为阴性，但无法排除组织胞浆菌病的诊断，则将猫排除在外。经细胞学或组织学证实患有组织胞浆菌病的猫被指定为确诊组织胞浆菌病例，而 UA-EIA 检测结果阳性但无细胞学或组织学证实的猫被指定为可能的组织胞浆菌病例。
10 只猫被诊断为确诊（n=6）或可能（4）组织胞浆菌病，10 只猫被认为是真正的阴性对照。20 只猫的全血 RT-PCR 结果均为阴性（敏感性，0%；95%置信区间，0%至 30.85%）。IgG-EIA 的敏感性为 90%（95%置信区间，55.50%至 99.75%），特异性为 70%（95%置信区间，34.75%至 93.33%）。所有确诊组织胞浆菌病的猫的 UA-EIA 结果均为阳性。
当在 EDTA 采集的全血上使用这种商用 RT-PCR 时，其敏感性较低，不应用于诊断猫的组织胞浆菌病。需要进一步研究以确定是否可以使用 EDTA 采集的全血的其他 RT-PCR 方案来诊断猫的组织胞浆菌病。
