Written by Carmella Wint and Matthew Solan | Published on July 25, 2012
Medically Reviewed by George Krucik, MD


Actinomycosis is a long-term infection that causes sores, or abscesses, in the body’s soft tissues. Actinomycosis is usually found in the mouth, nose, throat, lungs, stomach, or intestines. It rarely appears elsewhere in the body, but usually only if there is a break in the skin. While not contagious, it can spread from the initial infected area to other parts of the body. Actinomycosis is primarily found in tropical areas of the world.

What Causes Actinomycosis? Who is at Risk?

Actinomycosis is caused by a bacterium called Actinomyces israelii. This bacterium naturally

lives in the nose and throat and does not cause the infection on its own. It has to join with other bacterium (that enter the body through a break in the skin).

There are three other bacterium necessary for actinomycosis to develop. They are:

  • Actinomyces naeslundii
  • Actinomyces viscosus
  • Actinomyces odontolyticus

Since the infection spreads so slowly, actinomycosis was first thought to be a fungal infection. Actinomycosis is a rare infection, especially in the United States. But it is still possible to contract it. You are at a higher risk of developing actinomycosis if you:

  • have a damaged immune system from medications or another illness
  • are malnourished
  • neglect dental care after dental surgery or suffer other trauma to the mouth or jaw

One of the most common causes of actinomycosis is oral abscess. If you have recently had an oral abscess you should seek medical attention right away. Women who have used an intrauterine device (IUD) for birth control are also considered at high risk.

The Symptoms of Actinomycosis

Once the actinomycosis infection gets into the mouth tissue, it can cause what is commonly known as “lumpy jaw.” A hard lump can be felt in the jaw, though the lump itself is not typically painful. Yet, it can result in a painful skin abscess that first appears as a reddish bruise at the site. Actinomycosis can also cause muscle spasms in the jaw or a “locked jaw,” where the mouth cannot open in a normal way.

Other symptoms of actinomycosis are:

  • fever
  • weight loss
  • lumps on the neck or face
  • draining sores on the skin
  • excess sinus drainage
  • coughing
  • chest pain

Potential Long-Term Complications

Actinomycosis starts in the soft tissues of the body, but if left untreated can infect any surrounding bone. Surgery may be necessary to remove any infected bone. If the infection resides in the nasal sinuses, surgery may be required to remove damaged bone and tissue.

In rare cases, actinomycosis in the nasal sinuses can reach the brain. This may lead to another serious type of infection called meningitis.

Is Actinomycosis Easily Diagnosed? What Are the Treatments?

Actinomycosis is usually diagnosed through a study of fluid or tissue samples from the affected area. Your doctor uses a microscope to check the sample for Actinomyces bacteria. Any such bacteria appear as yellowish granules.

Antibiotics are the primary treatment for actinomycosis. High doses of penicillin are usually necessary to cure the infection. If you are allergic to penicillin, your doctor can use other antibiotics, such as tetracyclines, clindamycin, or erythromycin. It can take up to a year for the antibiotics to completely cure the infection.

Any skin eruptions (abscesses) from the infection may need to be drained or removed. If you developed actinomycosis due to the use of an IUD for birth control, the device should be removed to guard against from further infection.

Notify your doctor immediately if you show symptoms of actinomycosis, as early, aggressive treatment may spare you the need for surgery.

Preventing Actinomycosis

One of the best ways to prevent actinomycosis is to practice good oral hygiene. Schedule regular visits with your dentist so that he or she can spot potential problems that could turn into a serious condition. With proper treatment, actinomycosis is highly curable, and patients usually make a full recovery.

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