Definition of Pulmonary actinomycosis:

Pulmonary actinomycosis is a rare bacterial lung infection.

Causes, incidence, and risk factors:

Pulmonary actinomycosis is caused by one of two types of bacteria -- actinomyces or propioni. These bacteria are normally found in the mouth and gastrointestinal tract, where they do not usually cause harm. However, poor dental hygiene and dental abscess can increase your risk for face, jaw, and lung infections caused by these bacteria.

Alcohol abuse, having scars on the lungs (bronchiectasis), and emphysema are all associated with actinomycosis.

Actinomycosis in the lungs causes lung cavities, lung nodules, and pleural effusions. The disease is rare and may occur at any age, but most patients are 30-60 years old. Men get this infection more often than women do.