Actinomycosis is a bacterial infection that causes pus to collect in the body. The type depends on where it starts:

  • Jaw
  • Lungs
  • Abdomen
  • Uterus

Rarely, the infection can spread from one place in the body to another.

Abdominal Abscess

Abdominal Abscess
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Certain bacteria cause actinomycosis. They are normal in the mouth and sometimes in the bowels. They get into the body through breaks in the tissues. Tooth decay causes infections in the mouth and jaw. This is the most common type.

Risk Factors

Your chances of this infection are higher if you:

  • Are male
  • Have dental problems or had dental work
  • Draw in saliva, food, or drink into your lungs
  • Have long-lasting lung disease
  • Had bowel surgery
  • Have problems with an intrauterine device (IUD)
  • Have diabetes
  • Have weak immunity
  • Are malnourished


Symptoms depend on the where the infection starts. These may involve:

  • Swelling in the mouth, neck, or jaw
  • Pus that has tiny, yellowish specks
  • Pus that drains through the skin
  • Fever
  • Weight loss
  • Cough—with or without phlegm or blood
  • Swelling or a firm mass in the abdomen—mainly in the lower part


The doctor will ask about your symptoms and health history. You may have:

  • A physical exam
  • Testing of fluids, pus, or phlegm
  • A biopsy


Antibiotics treat the infection. Care also involves draining the infection site.

It’s common for the infection to come back, even after getting care.


Taking care of your mouth and teeth are the best way to lower your chances of infection. This involves:

  • Brushing your teeth twice a day
  • Flossing daily
  • Replacing your toothbrush every 3-4 months


Family Doctor—American Academy of Family Physicians
Mouth Healthy—American Dental Association


Canadian Dental Association


Actinomycosis. Merck Manual Professional Version website. Available at: Updated January 2018. Accessed May 21, 2018.
Cervicofacial actinomycosis. EBSCO DynaMed Plus website. Available at: http://www.dynamed... . Updated June 5, 2017. Accessed May 21, 2018.
Hall V. Actinomyces—gathering evidence of human colonization and infection. Anaerobe. 2008;14(1):1-7.
Naik NH, Russo TA. Bisphosphonate-related osteonecrosis of the jaw: the role of actinomyces. Clin Infect Dis. 2009;49(11):1729-1732.
Sullivan DC, Chapman SW. Bacteria that masquerade as fungi: actinomycosis/nocardia. Proc Am Thorac Soc. 2010;7(3):216-221.
Valour F, Sénéchal A, Dupieux C, et al. Actinomycosis: etiology, clinical features, diagnosis, treatment, and management. Infect Drug Resist. 2014;7:183-197.
Last reviewed May 2018 by David L. Horn, MD, FACP
Last Updated: 5/21/2018

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