Brain Abscess Caused by Enterococcus avium: A Case Report and Review of the Literature
A 48-year-old man with a 13-day history of headache and right otalgia was admitted to our tertiary medical center. He was diagnosed with type 2 diabetes mellitus 3 years earlier and was thereafter treated with oral hypoglycemic agents up until the current presentation. The patient had chronic suppurative otitis media for several years. Physical examination showed that his verbal output was reduced and his neurologic status was 11 on the Glasgow Coma Scale. The patient's temperature was 36.8℃, blood pressure was 140/100 mmHg, and pulse was 80 beats/min. Otoscopic evaluation revealed the exudation of fresh pus from the right ear. Laboratory studies revealed an elevated leukocyte count of 18,500/mm3 and an elevated C-reactive protein level of 18.9 mg/dL. Serological tests were negative for human immunodeficiency virus (HIV), hepatitis B, and hepatitis C. Brain magnetic resonance imaging (MRI) showed the presence of a 3.5-cm, rim-like enhancing lesion in the right temporoparietal lobe with perilesional edema (). Obliteration of the right mastoid air cells with sclerotic changes was noted, and its communication to the right mastoid was suspected. The patient underwent stereotactic aspiration of the brain abscess and treated with parenteral antibiotics, including ceftriaxone (2 g every 12 hours) and metronidazole (500 mg every 6 hours). Elective surgery was scheduled, but a follow-up computed tomography (CT) scan showed significant decreases in the extent of brain abscess due to abscess drainage through the communication site of the right ear. Therefore, the scheduled surgery was cancelled.\nOn day 6 of hospitalization, E. avium was isolate from ear discharge and aspirates of brain abscess culture. Species identification and antimicrobial susceptibilities of E. avium were determined using the MicroScan Pos Breakpoint Combo Panel Type 28 (Siemens, CA, USA). Ampicillin (2 g every 4 hours) was subsequently administered to the patient. Antibiotic susceptibility testing of the isolates showed that the pathogen was susceptible to penicillin, ampicillin, imipenem, glycopeptides, fluoroquinolones, and high level of aminoglycosides. Parenteral antibiotic therapy consisting of ceftriaxone, metronidazole, and ampicillin was continued for 4 weeks. After parenteral antibiotic therapy, the patient's neurologic deficits improved, and he was discharged in a stable condition with oral antibiotics. Oral antibiotic therapy comprising amoxicillin (500 mg every 8 hour) and levofloxacin (750 mg every 24 hours) was continued for 8 weeks. Compared the images of the initial MRI and the follow-up CT performed 1 month later, the abscess seemed to be completely resolved. Three months after diagnosis, the patient was full recovered without any residual neurologic deficits.