Actinomycosis

background

Actinomycosis is a subacute-to-chronic infection that causes periodontal (gum and jaw) disease. Subacute infections are between acute and chronic in duration, while chronic infections are infections that last more than six months. Actinomycosis infections of the gums and jaws are collectively known as cervicofacial actinomycosis or lumpy jaw disease. Actinomycosis infections can also occur in the chest, abdomen, and, in women, the pelvis.
Actinomycosis is caused by Actinomyces species, anaerobic-to-microaerophilic bacteria. Anaerobic bacteria grow in the absence of oxygen, whereas microaerophilic bacteria grow in the presence of oxygen but can switch from aerobic respiration to fermentation, which is a type of anaerobic respiration, when oxygen is not present. Fermentation is a process in which sugar is broken down for food in the absence of oxygen. An example of fermentation is the conversion of fruit juice to alcohol by yeast organisms.
The most common forms of Actinomyces are Actinomyces israelii, Actinomyces gerencseriae, and Propionibacterium propionicus. Some actinomycosis infections may involve up to 5-10 different species of bacteria. This type of infection is known as a polymicrobial infection.
Actinomyces is commonly found among the normal bacteria in the mouth and throat. In general, the skin and the entire digestive tract normally contain a number of different bacteria and other organisms. Each area of the digestive tract contains a different collection of flora, or organisms. Even the highly acidic environment of the stomach contains bacteria adapted to live there. For an infection to develop, the bacteria must be able to penetrate beneath the surface of the skin or mucous membranes. For example, a cut in the gums or an area of inflamed gum tissue might allow an infection to develop.
Actinomycosis spreads from the original site of infection to adjacent sites and often forms multiple abscesses, or pockets of infection, fistulas, and sinus tracts. Fistulas and sinus tracts are new passageways that form within tissues. For example, a fistula may form between the chest cavity and the skin.
Actinomycosis is a rare infection in the United States, which maybe due to the widespread use of antibiotics and dental hygiene practices that tend to be better than in many areas of the world. Worldwide, the infection is more common among people in low socioeconomic class, particularly those with poor dental hygiene and poor access to dental care.
Men are three times more likely than women to get this infection, for unknown reasons. All races are equally susceptible. Actinomycosis can affect people of all ages, but most cases occur in people from 20 to 50 years of age.

Related Terms

Abdominal actinomycosis, abscess, Actinomyces, actinomycosis, anaerobic bacteria, cervicofacial actinomycosis, dental hygiene, DNA, fistula, genomics, giant cells, Gram stain, granuloma, intrauterine device, IUD, lumpy jaw disease, macrophages, monoclonal antibodies, penicillin, periodontal disease, phagocytes, polymicrobial infection, subacute infection, sulfur granules, sinus tract, thoracic actinomycosis.

types of the disease

The most common forms of Actinomyces are Actinomyces israelii, Actinomyces gerencseriae, and Propionibacterium propionicus. Some actinomycosis infections may combine between five and 10 different species of bacteria. This type of infection is known as a polymicrobial infection.

research

One focus of current research is in the area of monoclonal antibodies. Monoclonal antibodies are protein structures that can attach to bacteria such as Actinomyces spp. and inactivate them. These antibodies can also be used for specific identification of the bacteria's DNA. Monoclonal antibodies are usually produced in a laboratory by injecting mice with a bacterium such as Actinomyces species; the mice then make antibodies against the bacterium, which are then harvested and used as a drug.
Studies have used monoclonal antibodies for Tropheryma whipplei, which belongs to the actinomyces group of bacteria. Mice were injected with two different strains of the bacteria. The monoclonal antibodies produced by the mice were used to identify the bacterium in stool samples.
Another study used adhesive fimbria of the bacterium to produce monoclonal antibodies. Adhesive fimbria are hair-like structures on the surface of the bacterium that allow it to attach to specific structures in the host organism; for example, adhesive fimbria allows Tropheryma whipplei to attach to intestinal cells. The researchers reported that the identification of the genetic structure of the fimbria may lead to better understanding of how the bacterium produces an infection. This further understanding may lead to improved treatments.

future research

Future research will focus in the same areas as current research. Genomics will be used to further define the genetic makeup of Actinomyces spp. This further understanding will aid in the diagnosis and treatment of the disease.