Rothia dentocariosa causing intracranial mycotic aneurysm and ischaemic stroke

Abstract

We describe a case of subacute bacterial endocarditis and mycotic brain aneurysm caused by Rothia dentocariosa due to untreated dental caries. R. dentocariosa is a rare cause of endocarditis that has a high incidence of aneurysmal and haemorrhagic complications. All patients with intracranial aneurysms who have signs of systemic infection should be considered to have mycotic aneurysms until proven otherwise. Dental habits should be included in regular medical assessment and dental care should be considered for patients presenting with infectious symptoms.

Background

This is a case of a patient presenting with ischaemic stroke secondary to mycotic aneurysm (MA). This case emphasises the importance of preventative dental care and that complications of untreated dental caries can be severe. MAs should be considered in patients with aneurysms and a history of compromised immunity and/or infectious symptoms.

Case presentation

A 62-year-old man with a history of hypertension, type 2 diabetes mellitus and dyslipidaemia presented to the emergency department with intermittent aphasia, left-sided temporal headache and eye pain. His vital signs, complete blood count and electrolytes were normal and he was admitted to the stroke service for investigation. During his hospital stay, the patient continued to experience left-sided temporal headaches and eye pain but denied changes in central vision. Giant cell arteritis was suspected because of these symptoms and its occasional manifestation with cerebral infarction.

Empirical treatment with 60 mg of oral prednisone was initiated and the patient was transferred to a tertiary centre for further evaluation.

Neuro-ophthalmological evaluation demonstrated central visual acuity of 20/80 on the right and 20/100 on the left. There was no relative afferent pupillary defect. Both optic nerves looked normal. There were no retinal emboli or Roth spots present. There were no conjunctival haemorrhages. As such, suspicion for giant cell arteritis was thought to be very low and steroid treatment was discontinued.

On further questioning, the patient endorsed poor dental hygiene and inconsistent dental care. Six months earlier during his last dental appointment, two lower molars and two upper molars demonstrated obvious caries with tooth decay also present under an existing filling in another upper molar which demonstrated deep penetration to the root of the tooth on X-ray. He unfortunately declined dental treatment at that time due to associated costs.

Investigations

On presentation in the initial hospital, CT of the brain showed an acute infarct in the left parietal-temporal region. Transthoracic echocardiography showed normal ventricular function with ejection fraction of 58%, mild left atrial dilation and no cardiac valve vegetations. Erythrocyte sedimentation rate and C reactive protein were elevated at 67 mm/hour and 43 mg/L. A temporal artery biopsy was performed and was interpreted as inconclusive. MRI of the brain was performed at the tertiary hospital and showed blood products within and adjacent to the infarcted tissue, raising the possibility of an underlying arteriovenous malformation (figure 1).

Figure 1.

CT of the brain, axial image (A) shows a region of hypodensity in the left parietal lobe. MRI of the brain shows corresponding hyperintensity on the diffusion-weighted images (B) and hypointensity on the apparent diffusion coefficient map (C), consistent with an acute infarct. Blood-sensitive gradient echo sequence (D) shows curvilinear regions of blood product within the infarcted tissue infarcted cortex consistent with petechial haemorrhage (short arrows), but also a more lobulated region of haemorrhage in the parenchyma or sulcus adjacent (long arrows).

CT angiography showed an immediately adjacent fusiform aneurysm of a distal branch of the left middle cerebral artery (figure 2). Transoesophageal echocardiography revealed a mobile echodensity on the atrial side of the posterior mitral valve leaflet measuring 3×3 mm. Blood cultures grew a Gram-positive organism identified as Rothia dentocariosa.

Figure 2.

Repeat CT of the brain at the tertiary centre (A), sagittal image shows a small amount of acute haemorrhage (arrow) corresponding to the lobulated blood on the previous MRI. CT angiography (B), coronal maximum intensity projection shows a fusiform aneurysm of a distal branch of the left middle cerebral artery (arrow and inset image) immediately adjacent to the acute haemorrhage. Catheter angiogram (C), left internal carotid injection shows the aneurysm as well.

Differential diagnosis

Patients presenting with acute neurological symptoms should be investigated for central or peripheral causes of neurological deficits based on the phenomenology. A patient presenting with aphasia and multiple vascular risk factors would most commonly present with an ischaemic stroke. Underlying artherosclerosis and thromboembolism is a common cause of stroke but other causes such as infectious, inflammatory or thrombotic causes should be considered. In our patient, complaints of periocular pain can raise the suspicion for giant cell arteritis which can manifest with cerebral infarction. In patients with poor dental hygiene, infectious aetiology of neurological deficits including MA and meningitis should be considered as possible aetiologies.

Treatment

While there is no good quality evidence to guide treatment of MAs, a common approach is first-line therapy with antibiotics, followed by surgical treatment in the presence of aneurysm growth or rupture.

Our patient received a 6-week course of intravenous ceftriaxone and the ruptured aneurysm was treated by endovascular embolisation using a total of 10 Target 360 and Target Helical nano coils (Stryker Neurovascular, Fremont, California, USA). Complete occlusion of the aneurysm was demonstrated at the end of the procedure.

Outcome and follow-up

The patient was transferred to a rehabilitation facility where he completed antibiotic treatment. His aphasia improved and headaches resolved. He did not endorse any lasting deficits and neurological examination 3 months following discharge was unremarkable.

Discussion

Subacute bacterial endocarditis (SBE) is an indolent form of endocarditis that often presents with vague symptoms such as fever, fatigue, tachycardia or anaemia. Risk factors for SBE include poor dentition or dental hygiene, prosthetic heart valves, rheumatic or congenital heart disease, immunosuppression, indwelling catheters, intravenous drug use and haemodialysis.¹ The causative organisms are most commonly Staphylococcus aureus or Streptococcus viridans but various other organisms are frequently reported as well. Clinical manifestations of SBE are numerous and classically taught using their eponymous names such as Roth spots, Janeway lesions and Osler’s nodes, representing embolic retinal haemorrhages and cutaneous embolic lesions, respectively.² Splinter haemorrhages and conjunctival petechiae are other findings seen on physical examination. Embolic complications of SBE are common and include stroke, pulmonary embolism and MAs.³

MAs refer to arterial wall outpouchings caused by any microorganism. MAs are rare, representing only 1%–4% of intracranial aneurysms.⁴ They develop due to inflammatory and bacterial factors that activate elastolytic and collagneolytic enzymes, leading to the breakdown of the vessel wall and subsequent aneurysm formation.⁵ Haematogenous spread of microorganisms can cause septic emboli to be lodged at distal artery branching points, thus MAs often arise from the distal branches of intracranial arteries. Septic emboli can result in arterial occlusion and cerebral infarction and sometimes abscess formation within the infarcted tissue. Loss of vessel-wall integrity can lead to fusiform enlargement of the artery and rupture.⁶

The diagnosis of MA can be difficult and requires a high index of suspicion. Mycotic aetiology of intracranial aneurysm should be considered in all patients with history of endocarditis, intravenous drug use, immunocompromised state or recent invasive procedures who exhibit signs of systemic infection.

Our patient was initially thought to have giant cell arteritis due to his ocular symptoms but further advanced neuroimaging would have confirmed the diagnosis and would have avoided unnecessary biopsies and steroid treatment. In his case, both SBE and MA were caused by R. dentocariosa which is a commensal oral Gram-positive bacterium that was first isolated in dental caries.⁷ There are multiple cases of R. dentocariosa causing infections elsewhere in the body including keratitis, endophthalmitis, peritonitis and septic arthritis but endocarditis remains its most commonly reported clinical manifestation.⁸ R. dentocariosa endocarditis often occurs in patients with underlying cardiac abnormalities undergoing dental procedures or in individuals with poor dental hygiene.⁹ Reported cases highlight patients whose first clinical manifestation of endocarditis was an ischaemic or haemorrhagic complication such as ischaemic stroke or subarachnoid haemorrhage. The incidence of MA formation has been reported to be as high as 25% in patients with R. dentocariosa endocarditis.⁸

The patient described in this case suffered two potentially life-threatening conditions, SBE and MA, due to untreated dental caries, highlighting that caries is not a benign condition and that dental hygiene and regular dental care are important determinants of systemic health. There is also evidence that periodontal disease is linked with multiple systemic conditions including infective endocarditis, rheumatoid arthritis, cardiovascular disease and poor glycaemic control.¹⁰ To prevent caries and periodontal disease, dental associations universally recommend tooth brushing with fluoride toothpaste two times per day and daily interdental cleaning with regular preventative follow-up visits.¹¹ Out-of-pocket costs of dental care are significant and serve as barriers to access.¹² The lack of preventative dental care can cause significant morbidity and mortality, compromising the quality of life and eventually increasing healthcare spending. This important public health issue should be further addressed and investigated.

Learning points.

• Dental hygiene and dental care should be included in the review of systems for patients with infection of an unknown source.

• Reminders about the importance of regular dental care should be part of every primary care practice.

• Rothia dentocariosa is a rare cause of endocarditis that has a high incidence of aneurysmal and haemorrhagic complications.

• Mycotic aneurysms should be considered in all patients with intracranial aneurysms who have signs of systemic infection.