17 December 2022

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Possible link between oral bacteria, brain abscesses

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The bacteria that cause oral infections can also contribute to patients developing life-threatening brain abscesses.

The new study, "Oral microbes and the formation of cerebral abscesses: A single-centre retrospective study," was published recently in the Journal of Dentistry. Study authors investigated brain abscesses and their association with bacteria present in the oral cavity. Although this type of abscess is relatively rare, it can lead to significant mortality and morbidity, according to a news release.

The researchers examined the histories of 87 patients admitted to the hospital with brain abscesses and used microbiological data obtained from abscess samples and peripheral cultures. This allowed the research team to investigate the presence of oral bacteria in the brain abscesses of patients in whom either a cause of the abscess had been found, as was the case in only 35 patients, or it had not been found.

The team's results showed that the 52 patients in whom no cause had been found were about three times as likely to have oral bacteria in their samples. These patients also had significantly higher counts of Streptococcus anginosus, a bacterium that can cause pharyngitis, bacteremia, and infections in internal organs such as the brain, lungs, and liver. This bacterium is usually found in dental abscesses.

Importance of oral health

In the study, the researchers said the findings suggest that the oral cavity could be considered a source of infection in brain abscess cases where no clear cause has been identified. The research was led by the University of Plymouth and University Hospitals Plymouth NHS Trust.

Dr Holly Roy, lead author and a clinical professor of neurosurgery at the University of Plymouth and University Hospitals Plymouth NHS Trust, said in a news release that although many potential causes of brain abscesses are recognized, the source of the infection often remains clinically unidentified.

"However, it is still surprising to frequently find bacteria of oral origin in brain abscesses of unexplained origin," she said. "It highlights the importance of using more sensitive techniques to assess the oral cavity as a potential bacterial source in brain abscess patients. It also highlights the importance of improving dental care and oral hygiene more generally.”

The study is part of ongoing research at the university's Oral Microbiome Research Group, led by Dr. Raul Bescos and Dr. Zoe Brookes, to explore the links between the oral microbiome and a range of cardiovascular and neurological conditions.

There are other clinical trials underway investigating the links between gum health and Alzheimer's disease and the identification of patients at high cardiovascular risk in primary care dental clinics, as an altered balance of oral bacteria (microbiome) during gum disease can lead to high blood pressure and stroke.

This article originally appeared in Odontologia33. 

Holly Roy et al. "Oral microbes and the formation of cerebral abscesses: A single-centre retrospective study." Journal of Dentistry. Published online 17 November 2022, version of record 5 December 2022. https://doi.org/10.1016/j.jdent.2022.104366