Acute disseminated actinomycosis presenting as pneumonia with bilateral pulmonary nodules and pelvic osteomyelitis in an immunocompetent patient

Actinomycosis is an indolent human infectious disease caused by gram-positive anaerobic filamentous bacteria Actinomyces. Despite its sluggish growth, clinical manifestations can be acute or chronic. Over the last five decades, a significant incidence decline in the western world is due to the discovery of effective antimicrobials and improved oral hygiene. Actinomycosis is now rarely encountered and often misdiagnosed as its manifestations mimic malignancy and other infectious diseases. Due to prior use of antimicrobials, laboratory diagnostic processes often fail to isolate the organism making it arduous to establish the diagnosis. Clinical classification is based on the geographical distribution of the disease as oro-cervicofacial, thoracic, abdominopelvic, neurologic, musculoskeletal, and disseminated. Disseminated and pulmonary actinomycosis in an immunocompetent individual is extremely rare. Here we present a 53-year-old healthy male presenting with acute disseminated actinomycosis with bilateral pulmonary nodules, right upper lobe pneumonia, and pelvic osteomyelitis from Actinomyces odontolyticus infection.