Bacteria that cause serious infections in the mouth may have effects far beyond the teeth and gums.
Scientists in Sweden have studied which bacteria are most often found in severe oral infections, hoping to better understand how mouth health may be connected with health throughout the body.
The research was carried out by scientists from Karolinska Institutet and was published in the journal Microbiology Spectrum. The team examined samples collected from patients with severe oral infections at Karolinska University Hospital over a 10-year period, from 2010 to 2020.
The human mouth naturally contains hundreds of types of bacteria. Many are harmless and are part of a healthy oral environment, but some can cause infections when they grow too much or enter damaged teeth, gums, or deeper tissues.
Researchers have become increasingly interested in the connection between oral health and diseases elsewhere in the body. Previous studies have found links between poor oral health and conditions including heart disease, diabetes, some cancers, and Alzheimer’s disease, although these links do not necessarily prove that mouth bacteria directly cause these diseases.
Until now, researchers have had relatively little long-term information about the bacteria involved in severe oral infections. The Swedish team wanted to identify the microbes that appeared most often and see whether their patterns had changed over time.
The researchers found bacteria from four major groups known as Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. More familiar types found frequently in the samples included Streptococcus, Prevotella, and Staphylococcus.
Some of these bacteria appeared in a large proportion of the infections. The researchers also found that certain harmful bacteria became more common in Stockholm during the decade covered by the study.
These findings matter because bacteria living in the mouth do not always remain there. When gums are inflamed or tissues are damaged, bacteria or substances produced by them may gain access to the bloodstream and potentially reach other parts of the body.
This does not mean that an oral infection will automatically cause a serious disease somewhere else. However, it gives scientists another reason to investigate whether certain mouth bacteria contribute to inflammation or disease in other organs.
The research team has previously studied possible links between oral bacteria and pancreatic cancer. In earlier work, some bacteria normally associated with the mouth were also detected in the pancreas, and their presence was linked with the severity of pancreatic tumors.
Such findings raise an important question about whether the mouth can sometimes act as a starting point or reservoir for bacteria that later appear elsewhere. More research is needed to understand how these microbes travel through the body and whether they actually influence the development or progression of disease.
The new study could also have practical value for dental care. Knowing which bacteria are most commonly involved in serious infections may help dentists and doctors improve diagnosis and choose more appropriate treatments.
Professor Sällberg Chen, who led the study, and the research team also hope for closer cooperation between dentistry and other areas of medicine. Oral health is often treated separately from general health, even though the mouth is part of the same body and can provide important clues about a person’s overall condition.
Good oral care remains important for preventing tooth decay, gum disease, and painful infections. Regular brushing, cleaning between the teeth, dental checkups, and early treatment of oral problems can help reduce the growth and spread of harmful bacteria.
The study adds to growing evidence that researchers should pay closer attention to the microbes living in the mouth. Understanding these bacteria may eventually help scientists explain some of the complex connections between oral infections and diseases affecting the rest of the body.
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