A 32-year-old woman has had a chronic cough with fever for the past month. On physical examination, her temperature is 37.5deg C. A chest radiograph shows many small, ill-defined nodular opacities in all lung fields. A transbronchial biopsy specimen shows interstitial infiltrates with lymphocytes, plasma cells, and epithelioid macrophages. Which of the following infectious agents is the most likely cause of this appearance?
Candida albicans
Cytomegalovirus
Enterobacter aerogenes
Mycobacterium tuberculosis
These findings suggest a granulomatous inflammation, and tuberculosis is a common cause. Candida is often a commensal organism in the oropharyngeal region and rarely causes pneumonia in healthy (non-immunosuppressed) individuals. Viral infections tend to produce a mononuclear interstitial inflammatory cell response. Bacteria such as Enterobacter and Staphylococcus are more likely to produce acute inflammation. Plasmodium produces malaria, a parasitic infection without a significant degree of lung involvement.
Inflammation & Repair