Delayed formation and rupture of intracranial aneurysm following Abiotrophia defectiva endocarditis.

Abiotrophia defectiva is a type of Streptococci and is a rare cause of infectious endocarditis. The progression and outcomes of infectious intracranial aneurysms (IIAs) associated with this species are unknown due to a limited number of reported cases. A woman in her 20s with a sudden headache had a subarachnoid haemorrhage on a head CT scan. Cerebral angiography showed an aneurysm on the right middle cerebral artery. She was diagnosed with infectious endocarditis caused by A. defectiva and underwent parent artery occlusion. Despite initiating targeted antibiotic therapy, a new IIA developed and ruptured 14 days postadmission. A second parent artery occlusion was performed on the new IIA. Following 6 weeks of continued antibiotic therapy, she underwent mitral valve repair and was discharged with no neurological symptoms. Endocarditis caused by A. defectiva can lead to the delayed formation of an IIA. Endovascular treatment was effective for repeated ruptured IIAs.