A 45-year-old man comes to the urgent care clinic because of fever, severe headache, myalgia, and pleuritic chest pain. He has had these symptoms for several days. Physical examination shows fever and mild tachycardia. Lung auscultation reveals mild crackles. Radiographic examination is consistent with segmental pulmonary infiltrates. The patient fails to respond to empiric antibacterial antibiotic therapy. Microscopic examination of lung tissue obtained from this patient shows spherules packed with endospores. This patient's history is most likely to reveal which of the following?

Question

A 45-year-old man comes to the urgent care clinic because of fever, severe headache, myalgia, and pleuritic chest pain.  He has had these symptoms for several days.  Physical examination shows fever and mild tachycardia.  Lung auscultation reveals mild crackles.  Radiographic examination is consistent with segmental pulmonary infiltrates.  The patient fails to respond to empiric antibacterial antibiotic therapy.  Microscopic examination of lung tissue obtained from this patient shows spherules packed with endospores.  This patient's history is most likely to reveal which of the following?

Quizplus · Accepted Answer

Coccidioides immitis is a dimorphic fungus that has a mold form (hyphae) at 25° C-30° C and an endospore form (spherules containing endospores, a unique characteristic of Coccidioides) at body temperature (37° C-40° C ). C. immitis is endemic to the southwestern United States (i.e., southern and central California, Arizona, New Mexico, and western Texas), northern Mexico, and some regions of Central and South America. Patients with coccidioidomycosis are likely to live in or have recently traveled to an endemic area. C. immitis is transmitted by spore inhalation. Spores are formed by fragmentation of hyphae. Once inside the lungs, the spores turn into spherules that contain endospores. The spherules subsequently rupture and release endospores that disseminate to other organs and tissues. Each endospore is capable of forming a new spherule. In immunocompetent hosts, C. immitis causes lung disease, which can be asymptomatic or cause flu-like symptoms (e.g., cough, fever, and myalgia) accompanied by erythema nodosum. In total, C. immitis can present in five ways: acute pneumonia (most common), chronic progressive pneumonia, pulmonary nodules and cavities, extrapulmonary nonmeningeal disease, and meningitis. The more severe manifestations are largely reserved for immunocompromised hosts. (Choice B) The yeast form of Cryptococcus neoformans is present in pigeon droppings. This fungus causes pulmonary disease and meningoencephalitis in immunocompromised patients. (Choice C) Histoplasma capsulatum is endemic to the Mississippi and Ohio River basins and found in bird and bat droppings. Patients with histoplasmosis often have a history of cleaning bird coops or caving. (Choice D) Aspergillus fumigatus can colonize old lung cavities (e.g., those formed by tuberculosis) to form a "fungal ball" (i.e., aspergilloma). Symptoms include cough, dyspnea, and hemoptysis. (Choice E) Neutropenic patients are at high risk for developing opportunistic mycoses. Candida albicans, A. fumigatus, Mucor, and Rhizopus species can cause severe disease in this population. (Choice F) Patients with asthma are at risk for developing an allergic reaction to A. fumigatus called allergic bronchopulmonary aspergillosis. Signs and symptoms include cough, dyspnea, wheezing, fever, and migratory pulmonary infiltrates. Educational objective: Coccidioides immitis is a dimorphic fungus endemic to the southwestern United States. It exists in the environment as a mold (with hyphae) that forms spores. These spores are inhaled and turn into spherules in the lungs. __________ References: Coccidioidomycosis. (http://www.ncbi.nlm.nih.gov/pubmed/18316002) Comparative genomic analyses of the human fungal pathogens Coccidioides and their relatives. (http://www.ncbi.nlm.nih.gov/pubmed/19717792)

A 45-Year-Old Man Comes to the Urgent Care Clinic Because