Health encyclopaedia - Alphabetical Topic List

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Actinomycosis is a chronic infection caused by various bacteria called actinomycetes. These bacteria are commonly found in the mouth and cheeks of humans and some other mammals. They do not cause an infection unless the bacteria enter the body through a break in the skin or the mucus tissues (such as the membranes in the mouth).

Actinomycosis most often occurs in the head and neck region. It can also be found in the abdomen, when someone takes in or eats the bacteria and it finds its way into the gastrointestinal system. If it has been breathed in via the mouth and nose, it may also infect the chest and lungs.

Before antibiotics were in widespread use, actinomycosis was a common condition. It is now rare in the UK but is found more commonly in tropical countries. More men than women tend to be diagnosed. It is rare in children but more often found in the elderly, who are more likely to have other dental or oral conditions that give access to the bacteria.

The bacteria causing infection in humans is usually a strain called Actinomyces israelii. The infection also occurs in other mammals such as cattle, but this is caused by a different strain of the bacteria.