Mycelial forms of Coccidioides spp. in the parasitic phase associated to pulmonary coccidioidomycosis with type 2 diabetes mellitus

Pulmonary coccidioidomycosis shares characteristics with other pulmonary pathologies. In tissue, spherules containing endospores are markers of Coccidioides immitis and C. posadasii infection. Mycelial forms presenting without classical parasitic structures are often misdiagnosed. The study was performed at the National Institute of Respiratory Diseases (INER) of Mexico between September 1991 and June 2005 and analyzed the association between cases, controls, and risk factors, including co-morbidity. A case was defined as any patient who presented mycelial forms and a control as any patient who presented only spherules or no parasitic forms. All patients (n=44) with pulmonary coccidioidomycosis were diagnosed by culture, histopathology, cytology, and immunology. Type 2 diabetic patients with pulmonary coccidioidomycosis were four times more likely than non-diabetics to develop parasitic mycelial forms (95% confidence interval [CI], 0.85-20.10; P<0.01). We formulated a comprehensive definition based on the results as follows: patients with pulmonary coccidioidomycosis with an evolution longer than 8 months, cough, hemoptysis, radiological evidence of a cavitary lesion, and type 2 diabetes mellitus, develop parasitic mycelial forms of Coccidioides spp. Based on microscopic images of patient specimens, we propose incorporating mycelial forms into the parasitic phase of Coccidioides spp. in patients with type 2 diabetes mellitus and chronic and cavitary pulmonary coccidioidomycosis.