What is pulmonary actinomycosis?

Pulmonary actinomycosis is a rare bacterial lung infection. It’s also known as thoracic actinomycosis. It’s not contagious.

This condition mainly affects people between 30 and 60 years old. It occurs more often in men than in women.

Treatment is generally successful in most cases, but it can be a lengthy process.

This condition is caused by bacteria from the genus Actinomyces. These bacteria normally live in your mouth and gastrointestinal tract. Most of the time they are harmless. However, they can cause an infection if tissue becomes damaged.

Infection usually occurs after illness or injury, such as a tooth abscess or gum disease. The damaged tissue increases the risk for the bacteria to infect your lungs or other parts of your body. There, it can cause harm.

In most cases, pulmonary actinomycosis occurs when a mixture of bacteria and food or secretions from the mouth or stomach accidentally end up in the lungs instead of the stomach. Inhaling things into the lungs that were meant to travel through the gastrointestinal tract is called aspiration.

Risk factors for this condition include:

  • dental abscess
  • not taking proper care of your teeth and gums
  • emphysema (a type of chronic obstructive lung disease)
  • scarred lungs from bronchiectasis
  • heavy alcohol use

Long-term alcohol use may weaken your immune system, causing a higher risk for infection. Heavy drinkers are also more likely to aspirate vomitus.

According to one study, another potential risk factor may be having a hiatal hernia.This is an abnormal condition where part of your stomach pushes up into your chest. Research is still preliminary.

Symptoms of pulmonary actinomycosis generally start slowly. Common signs include:

  • fever
  • fatigue
  • shortness of breath
  • weight loss
  • chest pain when inhaling deeply
  • night sweats
  • appetite loss
  • a cough with phlegm that might contain blood

Without treatment, pulmonary actinomycosis can permanently injure parts of your lungs. You could also develop a brain abscess or a central nervous system infection called infectious meningitis. These can be potentially life-threatening.

Other complications include emphysema and a serious bone infection called infectious osteomyelitis.

Symptoms of pulmonary actinomycosis are similar to those of other conditions. Therefore, your doctor might have to perform several tests to confirm the diagnosis. These include the following:

  • Lung biopsy. A small piece of lung tissue is removed and checked for signs of infection and other damage.
  • Bronchoscopy. A thin fiber-optic scope is used to see inside your lungs.
  • Complete blood count. This blood test will help look for signs of infection.
  • Chest CT scan. Specialized X-ray imaging used to make an image of your chest. This helps find abnormalities in your lungs.
  • Plain film chest X-ray imaging.
  • Sputum culture. This checks for infection, including bacterial, utilizing your phlegm sample.
  • Thoracentesis. Fluid is removed from the space (pleural cavity) that surrounds the outside of your lungs and is taken to the lab to test for infection.


Penicillin is the most common antibiotic treatment. It’s usually given in injections for two to six weeks. Then, oral penicillin or amoxicillin is used for 8 to 12 months. It can take up to 18 months of treatment for a cure.

If you’re allergic to penicillin, your doctor will prescribe alternate antibiotics like cefazolin or clindamycin.


You might need to have fluid surgically drained from your pleural cavity. Excess fluid in your pleural cavity, called pleural effusion, can have adverse effects on your lungs. This condition is potentially life-threatening.

Surgery can also be used to address tissue damage in your lungs.

Good dental hygiene can help lower your risk. Keep your teeth and gums in good shape. This helps prevent bacteria from overgrowing and spreading to other parts of your body. To do this:

  • Brush and floss your teeth twice a day.
  • Get regular dental cleanings and exams.
  • Eat fewer sugary foods. Sugary foods can increase your risk for tooth decay.