Summary: Previous research has linked oral bacteria and poor dental hygiene to an increased risk of Alzheimer’s disease. Now, researchers have discovered a link between Streptococcus anginosus, a bacteria found in oral abscesses, and an increased risk of brain abscesses.
Source: University of Plymouth
Bacteria known to cause oral infections may also be a contributory factor in patients developing potentially life-threatening abscesses on the brain, new research has shown.
The study, published in the Journal of Dentistry, investigated brain abscesses and their association with bacteria that occur in the oral cavity. While this type of abscess is relatively uncommon, it can result in significant mortality and morbidity.
Researchers examined the records of 87 patients admitted to hospital with brain abscesses, and used microbiological data obtained from abscess sampling and peripheral cultures.
This allowed them to investigate the presence of oral bacteria in patients’ brain abscesses where a cause of the abscess had either been found, as was the case in just 35 patients, or not found.
Their results showed that the 52 patients where no cause had been found were about three times as likely to have oral bacteria present in their samples.
Those patients also carried significantly higher counts of Streptococcus anginosus, a bacteria that can lead to pharyngitis, bacteremia, and infections in internal organs such as the brain, lung, and liver. This bacteria is often found in dental abscesses.
Writing in the study, researchers say the findings suggest that the oral cavity could be considered a source of infection in cases of brain abscess where no clear cause has been identified.
The University of Plymouth and University Hospitals Plymouth NHS Trust led the research.
Dr Holly Roy, an NIHR Clinical Lecturer in Neurosurgery based at the University of Plymouth and University Hospitals Plymouth NHS Trust, is the study’s lead author.
She said: “While many potential causes of brain abscesses are recognised, the origin of infection often remains clinically unidentified. However, it was still surprising to frequently find orally occurring bacteria in brain abscesses of unexplained origin.
“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 forms part of ongoing research taking place within 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.
Other clinical trials are underway investigating the links between gum health and Alzheimer’s disease and identifying patients under 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 strokes.
These clinical studies are being carried out in primary care dental facilities run by Peninsula Dental Social Enterprise, where the focus of the research is very much on improving clinical outcomes for patients.
About this brain abscess and oral health research news
Oral microbes and the formation of cerebral abscesses: A single-centre retrospective study
Intracranial abscesses are relatively uncommon, but can result in significant mortality and morbidity. Whilst many potential causes of brain abscesses are recognised, in many cases the origin of infection remains clinically unidentified. Our objective was to investigate the role of bacteria found in the oral cavity in the development of brain abscesses.
A retrospective analysis was performed using data from 87 patients admitted to a single UK neurosurgical unit with brain abscesses over a 16-year period. Using microbiological data obtained from abscess sampling and peripheral cultures, species of bacteria were categorised in patients where no primary source of infection was identified (NSI) for their brain abscess (n = 52), or where an infective source (ISI) was identified. The microbiological data was then screened to identify common oral bacteria in each group.
Brain abscesses from the ISI group (n = 35) demonstrated a significantly lower preponderance of oral bacteria (n = 8), than the NSI group (n = 29) (p < 0.05). Brain abscesses from the NSI group also had significantly higher counts of Streptococcus anginosus compared to ISI (p < 0.05), with brain abscesses being most common in the frontal and parietal lobes for both ISI and NSI.
These findings suggest that the oral cavity could be considered as a source of occult infection in cases of brain abscess where no clear cause has been identified. Future studies should include oral screening and microbiome analysis to better understand the mechanisms involved and develop approaches for prevention.
Clinical significance statement
Oral bacteria may be an under-recognised cause of brain abscesses. Careful review of oral health in brain abscess patients may help establish causation, particularly in patients with no cause for their abscess identified. Good levels of oral health may help prevent the development of brain abscesses in some individuals.