Oral microbes and the formation of cerebral abscesses: A single-centre retrospective study

Update and approach to patients with brain abscess

PURPOSE OF REVIEW

The epidemiology of brain abscess has changed in recent decades. Moreover, acute and long-term management remains challenging with high risks of mortality and neurological sequelae. This review describes recent advances in epidemiology, diagnosis, and treatment of brain abscess.

RECENT FINDINGS

The incidence of brain abscess is increasing, especially among elderly individuals. Important predisposing conditions include dental and ear-nose-throat infections, immuno-compromise, and previous neurosurgery. Molecular-based diagnostics have improved our understanding of the involved microorganisms and oral cavity bacteria including anaerobes are the predominant pathogens. The diagnosis relies upon a combination of magnetic resonance imaging, neurosurgical aspiration or excision, and careful microbiological examinations. Local source control by aspiration or excision of brain abscess combined with long-term antimicrobials are cornerstones of treatment. Long-term management remains important and should address neurological deficits including epilepsy, timely diagnosis and management of comorbidities, and potential affective disorders.

SUMMARY

A multidisciplinary approach to acute and long-term management of brain abscess remains crucial and source control of brain abscess by neurosurgery should be pursued whenever possible. Numerous aspects regarding diagnosis and treatment need clarification. Nonetheless, our understanding of this complicated infection is rapidly evolving.

Brain Abscess Caused by Oral Cavity Bacteria: A Nationwide, Population-based Cohort Study

BACKGROUND

Oral cavity bacteria are the most frequent etiology of brain abscess. Yet, data on the clinical presentation and outcome are scarce.

METHODS

We performed a nationwide, population-based study comprising all adults (aged ≥18 years) with brain abscess due to oral cavity bacteria in Denmark from 2007 through 2020. Prognostic factors for unfavorable outcome (Glasgow outcome scale, 1-4) were examined using modified Poisson regression to compute adjusted relative risks (RRs) with 95% confidence intervals (CIs).

RESULTS

Among 287 identified patients, the median age was 58 years (interquartile range, 47-66), and 96 of 287 (33%) were female. Preexisting functional impairment was absent or mild in 253 of 280 (90%), and risk factors for brain abscess included immunocompromise in 95 of 287 (33%), dental infection in 68 of 287 (24%), and ear-nose-throat infection in 33 of 287 (12%). Overall, a neurological deficit was present in 246 of 276 (86%) and in combination with headache and fever in 64 of 287 (22%). Identified microorganisms were primarily the Streptococcus anginosus group, Fusobacterium, Actinomyces, and Aggregatibacter spp., and 117 of 287 (41%) were polymicrobial. Unfavorable outcome occurred in 92 of 246 (37%) at 6 months after discharge and was associated with antibiotics before neurosurgery (RR, 3.28; 95% CI, 1.53-7.04), rupture (RR, 1.89; 95% CI, 1.34-2.65), and immunocompromise (RR, 1.80; 95% CI, 1.29-2.51), but not with specific targeted antibiotic regimens. Identified dental infection was associated with favorable prognosis (RR, 0.58; 95% CI, .36-.93).

CONCLUSIONS

Brain abscess due to oral cavity bacteria often occurred in previously healthy individuals without predisposing dental infections. Important risk factors for unfavorable outcome were rupture and immunocompromise. However, outcome was not associated with specific antibiotic regimens supporting carbapenem-sparing strategies.

Streptococcus constellatus Brain Abscess in a Middle-Aged Man With an Undiagnosed Patent Foramen Ovale

Brain abscess is a rare diagnosis. Common sources of infection include direct spread from otic sources, sinuses, or oral cavities, and hematogenous spread from distant sources, including the heart and lungs. Brain abscess with cultures growing oral flora species, in rare cases, may develop from bacteria in the oral cavity entering the bloodstream and then traveling to the brain via a patent foramen ovale. This report highlights a case of brain abscess caused by Streptococcus constellatus in a middle-aged man with an undiagnosed patent foramen ovale.