MacNeill Amy L, Alleman A Rick, Franklin Robert P, Long Maureen, Giguère Steeve, Uhl Elizabeth, López-Martinez Alric, Wilkerson Melinda
Department of Physiological Sciences, University of Florida College of Veterinary Medicine, Health Science Center, PO Box 100103, Gainesville, FL 32610-0103, USA.
Vet Clin Pathol. 2003;32(2):73-6. doi: 10.1111/j.1939-165x.2003.tb00317.x.
A 5-year-old Paso-Fino mare was presented for severe respiratory distress. The mare had foaled 2 months prior to presentation. The horse was in poor body condition with a dull hair coat. A mild fever was noted during physical examination and increased bronchovesicular sounds were auscultated. Thoracic radiographs showed an interstitial pattern and an alveolar infiltrate with distinct air bronchograms. Moderate purulent inflammation with increased mucus was observed in tracheal wash fluid, but no infectious agents were identified. A bronchoalveolar lavage (BAL) contained a large amount of mucus and reactive mononuclear phagocytes with variable numbers of intracellular fungal organisms morphologically consistent with Pneumocystis carinii. The mare had undetectable levels of immunoglobulin M (IgM) and decreased IgG levels in the serum. Immunophenotyping revealed decreased expression of major histocompatibility complex (MHC) class II molecules. Moderate to marked hyperplasia of type II epithelial cells was present throughout histologic sections of lung, but the fungal organisms were not observed. A culture system has not been developed for diagnosis of P carinii infection. Instead, diagnosis of P carinii pneumonia is achieved by microscopic identification of characteristic morphologic features of the pathogen. Cytologic examination of BAL fluid is the preferred method used to diagnose human infection with P carinii. In humans, the diagnostic sensitivity of cytology is significantly higher than the sensitivity of histopathologic examination of lung biopsies. The difference in sensitivity between BAL cytology and lung histopathology may also apply to the diagnosis of P carinii pneumonia in horses.
一匹5岁的 Paso - Fino母马因严重呼吸窘迫前来就诊。该母马在就诊前2个月产驹。这匹马身体状况不佳，被毛暗淡。体格检查时发现有低热，听诊支气管肺泡呼吸音增强。胸部X光片显示间质型和肺泡浸润，并伴有明显的空气支气管征。气管冲洗液中观察到中度脓性炎症且黏液增多，但未发现感染病原体。支气管肺泡灌洗（BAL）液中含有大量黏液和反应性单核吞噬细胞，其中有数量不等的细胞内真菌生物，形态与卡氏肺孢子虫一致。该母马血清中免疫球蛋白M（IgM）水平检测不到，IgG水平降低。免疫表型分析显示主要组织相容性复合体（MHC）II类分子表达减少。肺组织学切片中可见II型上皮细胞中度至明显增生，但未观察到真菌生物。目前尚未开发出用于诊断卡氏肺孢子虫感染的培养系统。相反，卡氏肺孢子虫肺炎的诊断是通过显微镜下识别病原体的特征性形态学特征来实现的。BAL液的细胞学检查是诊断人类卡氏肺孢子虫感染的首选方法。在人类中，细胞学诊断敏感性明显高于肺活检组织病理学检查的敏感性。BAL细胞学检查与肺组织病理学检查在敏感性上的差异可能也适用于马卡氏肺孢子虫肺炎的诊断。
