Brain Abscess Sustained by Actinomyces meyeri in an Immunocompetent Patient

Actinomycosis is a rare granulomatous disease, caused by filamentous Gram positive anaerobic bacteria, which may become pathogenic following disruption of anatomical barriers with invasion of host’s deep tissues and dissemination of infection to any site of the organism. A. israelii is found in most clinical presentations. We describe a case of a 41 years-old immunocompetent woman affected by thalamic abscess due to Actinomyces meyeri, presenting with fever, headache, vomit, confusion. A brain Computed Tomography (CT) and a Magnetic Resonance Imaging (MRI) revealed an expansive thalamic lesion with wide central necrosis and perilesionaledema. The patient was immediately addressed to a first evacuation of the mass, followed by a second drainage because of recurrence of the abscess. Microbiological and histological findings from intraoperatory specimens, resulted positive for A. meyeri. Ampicillin 20 g plus rifampicin 1200 mg/day was started, followed by ceftriaxon 4 g/day for 2 weeks and by amoxicillin 3 g/day. The treatment was discontinued after 9 months; brain MRIs performed at the end of therapy and after 3 and 6 months from the interruption of therapy revealed a gradual but complete resolution of cerebral abscess. Actinomycosis is an infrequent but severe disease that can mimic tuberculosis, nocardiosis and malignancies. Cases of cerebral actinomycosis reported in literature are limited, but those from A. meyeri are extremely rare. Moreover this pathogen is often related to disseminated disease, especially in immunocompromised patients. There is no consensus about treatment of cerebral actinomycosis: different types of regimens are proposed; we firstly administered ampicillin (12-16 g/day for at least six months), plus rifampicin, to enhance their penetration in CNS. Actinomycosis requires a prompt diagnosis and antibiotic treatment (often in combination with surgery) in order to avoid dissemination and prevent complications.