LQCL2510 - CMLE - Fatigue and Cough in a Patient on a TNF-alpha Blocking Agent-LQCL2510

LQCL2510 - Educational Activity

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The document is a section from the "ASCP LabQ Microbiology 2025" guide, focusing primarily on Histoplasma capsulatum, a dimorphic fungus responsible for histoplasmosis. The text outlines learning objectives, a case study, and provides an overview, diagnosis, and management strategies for histoplasmosis. <br /><br />The case study involves a 48-year-old male with Crohn's disease, treated with infliximab, presenting with symptoms consistent with histoplasmosis after hiking in bat caves in Costa Rica. Diagnostic investigations revealed numerous pulmonary nodules but were initially inconclusive for histoplasmosis. However, subsequent fungal cultures and other tests confirmed the presence of Histoplasma capsulatum. The patient received itraconazole treatment, his condition improved, and infliximab was discontinued.<br /><br />Histoplasma capsulatum inhabits soils rich in bird and bat droppings, commonly found in warm, humid climates. This fungus is endemic in the "Histo Belt" of the U.S. (Mississippi and Ohio River valleys) but can also be carried beyond these regions. Humans contract histoplasmosis through inhalation of airborne spores rather than through person-to-person transmission.<br /><br />Various forms of histoplasmosis exist, from mild respiratory symptoms to severe disseminated disease, particularly for immunocompromised individuals. Diagnosis typically involves urine antigen enzyme immunoassays, serum antibody testing, and fungal cultures. Other diagnostic techniques include molecular tests, histological examination with Grocott’s Methenamine Silver (GMS) stain, and chest radiography, although these have varying sensitivity and specificity.<br /><br />The report notes the importance of maintaining clinical vigilance for histoplasmosis regardless of geographic location due to its potential widespread dispersal. It provides additional resources and quiz questions to test comprehension of the subject matter, emphasizing critical knowledge for healthcare professionals managing this infection.

Keywords

Histoplasma capsulatum

histoplasmosis

dimorphic fungus

diagnosis

management strategies

Crohn's disease

infliximab

itraconazole

pulmonary nodules

Histo Belt