A 50-year-old man with a neurodegenerative disease has had a fever and cough productive of yellow sputum for the past 3 days. On physical examination, there is dullness to percussion at the left lung base. A chest radiograph shows areas of consolidation in the left lower lobe. Despite antibiotic therapy, the course of the disease is complicated by abscess formation, and he dies. At autopsy, there is a bronchopleural fistula surrounded by a pronounced fibroblastic reaction. Small, yellow, 1-cm to 2-mm "sulfur granules" are grossly visible within the area of abscess formation. Which of the following organisms is most likely to produce these findings?
Actinomycetes that can produce chronic abscessing pneumonia, particularly in immunocompromised patients, include Actinomyces israelii and Nocardia asteroides. Persons with neurodegenerative diseases are at risk for aspiration of oropharyngeal secretions that may contain these organisms. Sulfur granules, formed from masses of the branching, filamentous organisms, are more likely to be seen in Actinomyces. Blastomyces dermatitidis infections tend to produce a granulomatous inflammatory process. Chlamydial infections produce an interstitial pattern similar to that of most viruses. Klebsiella infections, similar to other bacterial infections, can result in abscess formation, although without distinct sulfur granules. Mycobacterium kansasii infections are similar to Mycobacterium tuberculosis infections in that granulomatous inflammation is prominent.
Actinomyces israelii
Blastomyces dermatitidis
Chlamydophila pneumoniae
Klebsiella pneumoniae
Infectious Disease