Study finds link between mouth bacteria and illnesses

Researchers at Sweden’s Karolinska Institutet have discovered the bacteria most commonly seen in severe oral infections. There haven’t been many studies like this one, so the researchers are hopeful that it can offer more insight on the association between oral bacteria and other illnesses. The study was published in Microbiology Spectrum.

Previous study has found clear links between oral health and common diseases such as diabetes, cancer, cardiovascular disease, and Alzheimer’s disease. However, few long-term studies have been undertaken to identify the exact bacteria prevalent in diseased oral- and maxillofacial regions.

Researchers at Karolinska Institutet found the most common bacteria after analysing samples obtained from patients with serious oral infections at Karolinska University Hospital in Sweden between 2010 and 2020. The research groups of Professor Margaret Sallberg Chen and adjunct Professor Volkan Ozenci collaborated on this project.

“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,” says Professor Sallberg Chen of the Department of Dental Medicine at Karolinska Institutet. “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.”

Involvement in other illnesses
Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria were the most prevalent bacterial phyla found in the samples, whereas Streptococcus spp, Prevotella spp, and Staphylococcus spp were the most common genera.

“Our results provide new insight into the diversity and prevalence of harmful microbes in oral infections,” says Professor Sallberg Chen. “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 researchers have previously demonstrated that the presence of oral bacteria in the pancreas correlates with the severity of pancreatic tumours. The study included 1,014 samples from the same number of patients, 469 women and 545 men, using a mass-spectrometric technology called MALDI-TOF, which quickly detects individual live bacteria in a sample but is seldom used in dental care.

“Our study was a single centre epidemiology study and to ensure the validity of the results we need to make more and larger studies,” says Volkan Ozenci at the Department of Laboratory Medicine, Karolinska Institutet. “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.”