Aggregatibacter actinomycetemcomitans

obsolete: Actinomyces actinomycetemcomitansOur oral cavity is a collection point for many different bacteria and germs. Despite daily dental care and the use of mouthwashes, there are about 500 different types of bacteria in the mouth. One of the best known is streptococci, which convert carbohydrates from food into lactic acid that attacks our teeth.

This is all better known as “caries“. Although this is one of the most common causes of dental diseases, there is another type of bacteria that can be found in the oral cavity, Aggregatibacter actinomycetemcomitans. This bacterium is one of the causes of gingivitis and periodontitis, an inflammation of the periodontium.


In order to be able to assess the exact significance of Aggregatibacter actinomycetemcomitans, it is necessary to classify it more closely. It is a Gram-negative (turns red in Gram staining; has a thin peptidoglycan layer of murein and an outer cell membrane) and non-mobile bacterium. It occurs in the oral flora and processes the food components ingested by humans.

Oral flora refers to all microorganisms that have settled in the oral cavity. It can metabolise maltose, fructose, glucose, mannose, carbohydrates, xylose and mannitol. Furthermore, its specifications include the fact that it can grow in both oxygen-rich (aerobic) and oxygen-poor (anaerobic) environments.

It is not dependent on oxygen. This bacterium is able to accelerate the reaction of hydrogen peroxide to oxygen and water. If the oral flora is pathologically (abnormally) altered, a single pathogen, in this case Aggregatibacter actinomycetemcomitans, may be present in increased numbers and thus cause a disturbance of the physiological oral flora. In this bacterium this leads to gingivitis and periodontitis.


Aggregatibacter actinomycetemcomitans does not originate from its own oral flora, but is transmitted and thus comes from “outside”. It can be transmitted by kissing, but also by sharing cutlery, glasses and toothbrushes. Especially a transmission from the parents to the child is clinically proven.

The main phase in which the parents can transmit the germs causing periodontitis to the child is during the eruption of the permanent teeth. However, this risk can be minimized by using separate cutlery and oral hygiene products, and by not licking the pacifier or spoon yourself. Your partner can also transmit Aggregatibacter actinomycetemcomitans through saliva exchange, as occurs during kissing.

However, this does not mean that periodontitis must break out, as other factors also play an important role. For example, a person who carries the bacterium in his oral flora but who has never had problems with periodontitis himself can transmit Aggregatibacter actinomycetemcomitans to another person, in whom an inflammation of the periodontal apparatus then develops. The bacterium can penetrate the tissue, which is why it is very persistent and can reappear despite treatment. Periodontitis is therefore a real infectious disease.