Nosanchuk J D, Snedeker J, Nosanchuk J S
Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA.
Int J Infect Dis. 1998 Jul-Sep;3(1):32-5. doi: 10.1016/s1201-9712(98)90092-3.
Coccidioides immitis is a dimorphic fungus capable of causing a diverse spectrum of disease in humans. Although the diagnostic pathologic finding in tissue is a mature endosporulating spherule, hyphal structures can also be found in over 50% of pathologic specimens. This report presents a case of coccidioidomycosis in which there were no intact spherules, but characteristic barrel shaped arthrospores present in tissue and cultures positively identified the organism as C. immitis. This case was further complicated by presentation in a nonendemic area for the fungus. Coccidioides immitis is a soil fungus with two distinct phases: the saprophytic and the parasitic. This biphasic life cycle was first described by Ophöls,1 and more fully characterized by Baker and colleagues. The saprophytic stage occurs in the environment with the organism existing in a mycelial state. As the mold matures, barrel-shaped arthroconidia form and alternate with empty cells. The arthroconidia subsequently fracture from hyphae and are dispersed as an aerosol. The saprophytic cycle repeats itself upon infection of a new soil site. However, if the airborne arthroconidia are inhaled by a susceptible host, the parasitic phase is initiated. In the parasitic cycle, the arthrospore swells and becomes a rounded structure, known as a spherule. The protoplasm of the spherule divides to form large numbers of endospores. If the spherule ruptures, the endospores are released. Each endospore can develop into a new spherule, or, upon expulsion via contaminated secretions from the host, return to the environment where it transforms into its mycelial form. Although the characteristic histologic finding in coccidioidomycosis is the spherule with endospores, hyphal forms also can be found. The mycelial form of C. immitis cannot be definitively identified morphologically and requires confirmation by culture techniques or genetic probes. This report presents a pulmonary coccidioidoma in which arthroconidia were the predominant forms found in tissue.
粗球孢子菌是一种双相真菌，可在人类中引起多种疾病。虽然组织中的诊断性病理发现是成熟的产内孢子球形体，但在超过50%的病理标本中也可发现菌丝结构。本报告介绍了一例球孢子菌病病例，其中组织中没有完整的球形体，但有特征性的桶状关节孢子，培养物中阳性鉴定该病原体为粗球孢子菌。该病例因发生在该真菌的非流行地区而更加复杂。粗球孢子菌是一种土壤真菌，有两个不同阶段：腐生阶段和寄生阶段。这种双相生命周期最早由奥费尔斯描述，1 并由贝克及其同事进行了更全面的特征描述。腐生阶段发生在环境中，该生物体以菌丝状态存在。随着霉菌成熟，桶状关节分生孢子形成并与空细胞交替。关节分生孢子随后从菌丝断裂并以气溶胶形式分散。一旦感染新的土壤位点，腐生循环就会重复。然而，如果易感宿主吸入空气中的关节分生孢子，就会启动寄生阶段。在寄生循环中，关节孢子膨胀并变成圆形结构，称为球形体。球形体的原生质分裂形成大量内孢子。如果球形体破裂，内孢子就会释放出来。每个内孢子可以发育成一个新的球形体，或者通过宿主受污染的分泌物排出后，回到环境中转化为菌丝体形式。虽然球孢子菌病的特征性组织学发现是带有内孢子的球形体，但也可以发现菌丝形式。粗球孢子菌的菌丝体形式不能通过形态学明确鉴定，需要通过培养技术或基因探针进行确认。本报告介绍了一例肺球孢子菌肿，其中关节分生孢子是组织中发现的主要形式。
