Actinomycosis is a rare type of bacterial infection. Most bacterial infections are confined to one part of the body because the bacteria are unable to penetrate through the body’s tissue. However, actinomycosis is unusual in that the infection is able to move slowly but steadily through the body’s tissue.
Symptoms of actinomycosis include:
- swelling and inflammation of affected tissue
- tissue damage that results in scar tissue
- formation of abscesses (pus-filled swellings)
- small holes or tunnels that develop in tissue and leak a type of lumpy pus
Actinomyces bacteria
Actinomycosis is caused by a family of bacteria known as actinomyces bacteria. In most cases, the bacteria live harmlessly on the lining of the mouth, throat, digestive system and the vagina (in women).
The bacteria only pose a problem if the tissue lining becomes damaged by injury or disease, allowing the bacteria to penetrate deeper into the body. This is potentially serious because the actinomyces bacteria are anaerobic bacteria, which means they thrive in parts of the body where there are low levels of oxygen, such as deep inside human tissue.
However, one advantage of the fact that actinomyces bacteria are anaerobic is that they cannot survive outside the human body. This means that actinomycosis is not a contagious condition.
Types of actinomycosis
In theory, actinomycosis can develop almost anywhere inside the tissue of the human body. But the condition tends to affect certain areas of the body and can be classified into four main types:
- oral cervicofacial actinomycosis
- thoracic actinomycosis
- abdominal actinomycosis
- pelvic actinomycosis
These are described below.
Oral cervicofacial actinomycosis
Oral cervicofacial actinomycosis is where the infection develops inside the tissue of the neck, jaw or mouth. Most cases are caused by dental problems, such as tooth decay.
Oral cervicofacial actinomycosis is the most common type of actinomycosis and accounts for an estimated half of all cases.
Thoracic actinomycosis
Thoracic actinomycosis is where the infection develops inside the lungs or associated airways. It is thought that most cases of thoracic actinomycosis are caused by people accidentally inhaling droplets of contaminated fluid into their lungs.
Thoracic actinomycosis accounts for an estimated 15-20% of cases.
Abdominal actinomycosis
Abdominal actinomycosis is where the infection develops inside the abdomen (tummy). This type of actinomycosis can have a range of potential causes. It can develop as a secondary complication of a more common infection, such as appendicitis, or after accidentally swallowing a foreign object, such as a chicken bone containing the actinomyces bacteria.
Abdominal actinomycosis accounts for an estimated 20% of all cases.
Pelvic actinomycosis
Pelvic actinomycosis is where the infection develops inside the pelvis (the bony structure that includes the hip bones). Pelvic actinomycosis usually only occurs in women because most cases are caused when the actinomyces bacteria are spread from the female genitals into the pelvis.
It is thought that most cases of pelvic actinomycosis are associated with the long-term use of the intrauterine device (IUD) type of contraceptive, which is often referred to as the coil. The coil is a T-shaped device that fits inside the womb.
Pelvic actinomycosis accounts for an estimated 10% of all cases.
How common is actinomycosis?
Actinomycosis is one of the rarest types of bacterial infections. It is thought that, in developed countries, such as England, just one person in every 300,000 will develop actinomycosis in any given year. On average, there are 100 admissions to hospital each year in England due to actinomycosis.
Actinomycosis is probably more widespread in parts of the world where access to antibiotics is limited and dental hygiene standards are poor. However, it is difficult to estimate the extent of the condition worldwide because reliable data are not easy to obtain.
Three out of every four cases of actinomycosis affect men, who are usually between 20 and 60 years of age. The reasons for this are unclear.
Outlook
The infection responds well to treatment, although it is usually necessary to take a course of antibiotics lasting for several months to ensure that all the bacteria are wiped out.
In some cases of actinomycosis, minor surgery may be required to repair the damaged tissue and to drain pus out of the abscesses.
Glossary
Antibiotics
Antibiotics are medicines that can be used to treat infections caused by micro-organisms, usually bacteria or fungi. For example amoxicillin, streptomycin and erythromycin.
Bacteria
Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and some others are good for you.
Chronic
Chronic usually means a condition that continues for a long time or keeps coming back.
Lungs
Lungs are a pair of organs in the chest that control breathing. They remove carbon dioxide from the blood and replace it with oxygen.
Tissues
Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.
Last updated: 18 January 2012
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