Focal Neurological Symptoms at Initial Presentation Could Be a Potential Risk Factor for Poor Prognosis Among Patients With Multiple Brain Abscesses by Streptococcus anginosus Group: A Case Report With Literature Review

Streptococcus anginosus group (SAG) is one of the most common microbes of brain abscesses. Brain abscesses caused by SAG have often delayed diagnosis since both blood and cerebrospinal fluid cultures are negative in half of the cases. A 68-year-old man developed persistent fever, headache, and myalgias for two weeks and visited our department. He was treated with oral antibiotics without laboratory work. Although examination showed no focal neurological symptoms, a careful interview revealed a history of unusual behavior for a few minutes on the previous day. Whole body contrast-enhanced computed tomography (CT) and head magnetic resonance imaging (MRI) showed two ring enhancements close to the bilateral ventricles, which were consistent with a diagnosis of the brain abscesses. An emergent surgical puncture for the larger abscess with intravenous antimicrobial therapy quickly improved his condition, and he was discharged on day 36 with no sequelae. We retrospectively reviewed works of literature on cases with multiple brain abscesses by SAG to assess potential prognostic factors for neurological sequelae. Statistical analyses of 12 cases, including 11 cases from the literature review and the current case, were performed between groups with or without poor prognosis. Among potential risk factors of age, sex, focal neurological symptoms, duration from onset to treatment, abscess formation of other organs, presence of surgical drainage, and positive for blood culture, only focal neurological symptoms at the initial presentation were significantly associated with poor prognosis (no poor prognosis, 1/4 cases vs poor prognosis group, 8/8 cases; p=0.01). Careful interviews and detailed examinations should be conducted to assess the possibility of brain abscesses among patients with fever of unknown etiology. Otherwise, a delayed diagnosis might result in poor prognoses such as death or neurological sequelae due to this disease's nature, which has few specific symptoms in the early stages.