Cerebral Arteritis Caused by a Streptococcus Anginosus Group Infection Leading to Sequential Cerebral Infarction and Intracerebral Hemorrhage.

A 55-year-old man was admitted with a right frontal headache and low-grade fever. The initial neuroimaging and cerebrospinal fluid findings were normal, and giant cell arteritis was suspected. After administering prednisolone therapy, he developed a cerebral infarction and multiple cerebral arterial stenoses. Blood cultures were positive for the Streptococcus anginosus group, and the cerebrospinal fluid findings were consistent with bacterial meningitis. Echocardiography revealed no valvular vegetations. Although antibiotic therapy improved the patient's symptoms, intracerebral hemorrhage developed thereafter. The patient was discharged with residual neurological deficits. This case suggests that Streptococcus anginosus group infections can cause cerebral arteritis.