A serious infection in the mouth may be more than a dental problem.
Scientists in Sweden have identified the bacteria most often found in severe oral infections, adding to growing evidence that the health of the mouth may be closely connected with health elsewhere in the body.
The research was led by Professor Margaret Sällberg Chen and colleagues at Karolinska Institutet. The study was published in the journal Microbiology Spectrum and examined samples collected from patients treated for serious oral infections at Karolinska University Hospital.
The human mouth contains hundreds of types of bacteria. Many normally live there without causing trouble, but problems can develop when harmful bacteria multiply, enter damaged tissue or become trapped around teeth and gums.
This can lead to painful infections, swelling and damage to teeth or surrounding tissue. In severe cases, an infection can spread beyond its original location and require urgent medical or dental treatment.
Scientists have also become increasingly interested in connections between oral health and diseases affecting other parts of the body. Previous studies have found associations between poor oral health and conditions including heart disease, diabetes, some cancers and Alzheimer’s disease.
However, an association does not necessarily mean that bacteria in the mouth directly cause these diseases. Researchers are trying to understand whether oral bacteria contribute to illness, whether disease changes the bacteria living in the mouth, or whether other factors influence both.
For the Swedish study, researchers examined samples from patients with severe oral infections collected at Karolinska University Hospital between 2010 and 2020. Looking across a decade of samples allowed the team to identify which bacteria repeatedly appeared in these infections.
The most frequently detected bacteria belonged to four large groups known as Firmicutes, Bacteroidetes, Proteobacteria and Actinobacteria. Among the commonly identified types were Streptococcus, Prevotella and Staphylococcus.
Some members of these bacterial groups normally live in or around the human body, while others can cause disease under the right conditions. The researchers also found that some potentially harmful bacteria became more common in oral infection samples in Stockholm during the period studied.
These findings could help doctors and dentists better understand what is happening inside serious dental infections. Knowing which bacteria are most likely to be involved may eventually improve testing and help health professionals choose the most suitable treatment.
The research is also important because bacteria do not always remain confined to the mouth. Oral bacteria or substances produced during inflammation can potentially enter the bloodstream, especially when gums or other tissues are damaged.
Sällberg Chen’s research team has previously investigated oral bacteria found in pancreatic tissue. Their work suggested that the presence of certain bacteria could be related to the severity of pancreatic tumors, raising further questions about how microbes from the mouth may interact with distant organs.
That does not mean that having a dental infection will cause pancreatic cancer or another serious disease. Instead, the findings show why scientists want to study the relationship between oral microbes, inflammation and general health more closely.
The researchers hope the work will encourage greater cooperation between dental professionals, microbiologists and medical researchers. Combining knowledge from these fields could improve understanding of how oral infections develop and whether particular bacteria can influence diseases elsewhere in the body.
The study also offers another reason to take everyday oral care seriously. Regular brushing, cleaning between the teeth and dental checkups can help prevent tooth decay and gum disease and allow infections to be found before they become severe.
Scientists still have much to learn about exactly how mouth bacteria affect the rest of the body. But the new research reinforces an increasingly important message: the mouth is part of the body, and protecting oral health may have benefits that extend well beyond teeth and gums.
If you care about inflammation, please read studies about the big cause of inflammation in common bowel disease, and vitamin B may help fight COVID-19 and reduce inflammation.
For more health information, please see recent studies about new way to halt excessive inflammation, and results showing foods that could cause inflammation.
Copyright © 2026 Knowridge Science Report. All rights reserved.
