- Department of Neurosurgery, Tsukuba Memorial Hospital, Tsukuba,
- Department of Neurosurgery, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan.
Eiichi Ishikawa, Department of Neurosurgery, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan.
DOI:10.25259/SNI_783_2021Copyright: © 2021 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Yu Akimoto1, Kiyoyuki Yanaka1, Kuniyuki Onuma1, Kazuhiro Nakamura1, Eiichi Ishikawa2. Prevotella brain abscess in a healthy patient with a patent foramen ovale: Case report. 02-Nov-2021;12:548
How to cite this URL: Yu Akimoto1, Kiyoyuki Yanaka1, Kuniyuki Onuma1, Kazuhiro Nakamura1, Eiichi Ishikawa2. Prevotella brain abscess in a healthy patient with a patent foramen ovale: Case report. 02-Nov-2021;12:548. Available from: https://surgicalneurologyint.com/?post_type=surgicalint_articles&p=11208
Background: Brain abscesses are relatively rare life-threatening infectious lesions often concomitant with a direct spillover of inflammation in the head or neck, hematogenous infections, and immunocompromised conditions. They rarely occur in adults without such predisposing factors. Prevotella is a well-known dental pathogen that very rarely causes brain abscesses.
Case Description: We report such an abscess in a 51-year-old man who was innately healthy and had no oral lesions. A comprehensive computed tomography examination of the chest, abdomen, and pelvis, was inconclusive but a transesophageal echocardiogram bubble study revealed a mild patent foramen ovale (PFO) that matched Grade 1 criteria. We deduced that the right-left shunt due to the PFO could have contributed to the brain infection and treated the patient successfully via surgical abscess aspiration and antibiotics.
Conclusion: In case of a brain abscess occurring in healthy adults, it is essential to investigate the source of infection and the existence of an arterio-venous shunt, such as PFO.
Keywords: Brain abscess, Patent foramen ovale, Prevotella
Brain abscesses are relatively rare, with a prevalence of 0.4–0.9/100,000 people, but they are the most severe with a fatality rate of 10% at onset.[
The most common microorganisms reported in brain abscesses are from Streptococci, Bacteroides, and Enterobacteria families in addition to Staphylococcus aureus.[
Here, we report on a Prevotella brain abscess that occurred in a healthy adult with an undiagnosed PFO and also review relevant literature.
A 51-year-old previously healthy man who had no apparent oral cavity lesions presented with a headache and speech disturbance that had been present for a week. He had no history of trauma, surgery, or medical treatment for any serious illnesses, including immunological disorders. At the time of his visit, he had no fever and no signs of meningeal irritation. Blood sampling at the time of admission showed a white blood cell count of 9470/μL, a C-reactive protein level of 1.54 mg/dL, and an erythrocyte sedimentation rate of 85 mm, indicating mildly elevated parameters, but there were no decreases in complement or antibody levels. Head computed tomography (CT) on admission showed a mass lesion with brain edema in the left frontal lobe [
(a) A non-contrast head computed tomography on admission showing a mass lesion with edema in the left frontal lobe. (b) A non-contrast T1-weighted magnetic resonance (MR) image showing a mass lesion in the left frontal lobe. (c) A gadolinium-enhanced MR image showing a ring-enhancement. (d) A diffusion-weighted image (without gadolinium) showing a significant restriction of diffusion in the lesion.
On the day after admission, we drained the abscess through a drainage tube from the lesion cavity and aspirated a light red mucus. Although the patient’s blood cultures were negative, Prevotella intermedia was detected in the surgical cultures. Since P. intermedia is an oral endogenous bacterium, a dentist examined the patient, but no noticeable lesions were found in the oral cavity. Contrast-enhanced chest, abdomen, and pelvis CT scans, coupled with transthoracic echocardiography to scrutinize the infection source and possible arterio-venous (AV) shunts, were unremarkable. However, a transesophageal echocardiogram (TEE) bubble study (based on bubbles detected in the left atrium) revealed several reproducible bubbles within a three-heartbeat span in the left ventricular system, suggesting the presence of a Grade 1, mild PFO [
Antimicrobial therapy was initially guided by the literature, with third-generation cephem, vancomycin, and intravenous dexamethasone for cerebral edema. Since anaerobic bacteria were suspected as the causative organism of the abscess, the antibiotic was changed to cefmetazole. After detecting P. intermedia, along with the results of sensitivity testing to antibiotics, piperacillin-tazobactam and metronidazole were used [
In this case, abscess drainage was performed before antimicrobial therapy as recommended by guidelines when the causative pathogen cannot be identified.[
Brain abscesses in healthy individuals are rare[
In the present case, we decided to closely monitor the patient rather than perform PFO closure because the shunt volume was small and there were no PFO-related symptoms. In the case of cryptogenic ischemic stroke, PFO closure is associated with a lower rate of recurrent ischemic strokes than medical therapy alone.[
We treated a brain abscess caused by P. intermedia in a healthy adult with undiagnosed PFO. Since, even in healthy adults, the small size of a PFO can cause brain abscesses, it is essential to conduct a thorough search for the source of infection in such patients. When a brain abscess occurs in a healthy person, a comprehensive examination is required to identify the source of infection and the presence of an AV shunt, including TEE with microbubble testing.
The authors certify that they have obtained all appropriate patient consent.
There are no conflicts of interest.
The authors would like to thank Dr. Alexander Zaboronok of the University of Tsukuba Faculty of Medicine Department of Neurosurgery and Dr. Bryan J. Mathis of the University of Tsukuba Hospital International Medical Center for professional and language revision.
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