Study sheds new light on the link between oral bacteria and diseases

Researchers at Karolinska Institutet in Sweden have identified the bacteria most commonly found in severe oral infections. Few such studies have been done before, and the team now hopes that the study can provide deeper insight into the association between oral bacteria and other diseases. The study is published in Microbiology Spectrum.¹

Margaret Sällberg Chen, Professor at the Department of Dental Medicine at Karolinska Institutet, Sweden. Photo: Stefan Zimmerman

Previous studies have demonstrated clear links between oral health and common diseases, such as cancer, cardiovascular disease, diabetes and Alzheimer's disease. However, there have been few longitudinal studies identifying which bacteria occur in infected oral and maxillofacial regions. Researchers at Karolinska Institutet have now analysed samples collected between 2010 and 2020 at the Karolinska University Hospital in Sweden from patients with severe oral infections and produced a list of the most common bacteria.

This was a collaborative study that was performed by Professor Margaret Sällberg Chen and adjunct Professor Volkan Özenci's research groups.

Professor Sällberg Chen of the Department of Dental Medicine at Karolinska Institutet said: ‘We're reporting here, for the first time, the microbial composition of bacterial infections from samples collected over a ten-year period in Stockholm County. The results show that several bacterial infections with link to systemic diseases are constantly present and some have even increased over the past decade in Stockholm'.

The study shows that the most common bacterial phyla amongst the samples were Firmicutes, Bacteroidetes, Proteobacteria and Actinobacteria, while the most common genera were Streptococcus spp, Prevotella spp, and Staphylococcus spp.

Professor Sällberg Chen said: ‘Our results provide new insight into the diversity and prevalence of harmful microbes in oral infections. The finding isn't only of importance to dental medicine, it also helps us understand the role of dental infection in patients with underlying diseases. If a certain bacterium infects and causes damage in the mouth, it's very likely that it can be harmful to tissues elsewhere in the body as the infection spreads'.

The research group has previously shown that the occurrence of oral bacteria in the pancreas reflects the severity of pancreatic tumours.

Professor Volkan Özenci at the Department of Laboratory Medicine, Karolinska Institutet, said: ‘Our study was a single-centre epidemiology study and to ensure the validity of the results we need to make more and larger studies. We now hope that dentists will collaborate with clinical microbiology laboratories more to gain a better understanding of the bacteria that cause dental infections, to improve diagnostics and therapeutic management of oral infections'.