New-onset seizures and a tangled up Gram’s stain: Actinomyces brain abscess

Abstract

A 62-year-old male with a past medical history of diabetes mellitus presents to the Emergency Department for evaluation of new-onset generalized tonic-clonic seizures resulting in tongue bite and minor trauma. Upon arrival, he was confused and agitated and unable to provide any further history. Initial laboratory workup revealed a leukocytosis of 11.2 cells/μL (normal 3.4–9.6 cells/μL), with 83 % neutrophils. Head magnetic resonance imaging with intravenous contrast revealed a left parietal lobe ring-enhancing lesion in the grey-white matter junction measuring 1.3 cm with associated surrounding edema concerning for brain abscess. Blood cultures were obtained, and the patient was started empirically on cefepime, metronidazole, and vancomycin. A stereotactic brain biopsy was performed and showed gram-positive cocci, Gram-negative cocci and beaded branching Gram-positive bacilli, with a negative modified acid-fast staining (Fig. 1, Fig. 2). The cultures grew Actinomyces georgiae, Streptococcus intermedius, Streptococcus mitis, and Staphylococcus epidermidis. Fig. 1 Gram’s stain of brain tissue biopsy at 100× magnification showing Gram-positive cocci and Gram-negative cocci. Fig. 1 Fig. 2 1000× magnification of the brain abscess showing Gram-positive branching bacilli. Fig. 2 The initial presentation of our case is consistent with brain actinomycosis in a patient with diabetes resulting in seizures. Actinomycosis is an invasive infection due to bacteria in the genus Actinomyces, which consist of filamentous non-spore-forming, anaerobic, Gram-positive commensal bacteria found in the human mouth, gastrointestinal tract, and ubiquitously in the soil. Actinomyces georgiae has mainly been described as normal oral microbiota in healthy humans. The presence of other “companion pathogens” that facilitate Actinomyces virulence, such as Streptococcus spp. and coagulase-negative staphylococci is commonly described in actinomycosis (65–95 %), as seen in our patient [1]. Actinomycosis of the central nervous system (CNS) is rare and most likely results from hematogenous or contiguous infection. CNS involvement of Actinomyces sp. may include meningitis or meningoencephalitis, actinomycoma, subdural empyema, epidural abscess, and single or multiple brain abscesses. Several cases have been described [[2], [3], [4], [5]], and a combination of highly-bioavailable antibacterials with good CNS penetration plus surgical debridement, if amenable, is key in the management of CNS actinomycosis [5]. Actinomyces spp. have been shown to be susceptible to penicillin, ceftriaxone, vancomycin, and linezolid with small differences amongst species. Extended treatment duration of oral agents such as penicillin, amoxicillin, or quinolones is recommended following surgical intervention. Our patient completed a 6-week course of ceftriaxone before transitioning to amoxicillin to complete 12 months for the treatment of brain actinomycosis. He was seen at a 1-year follow-up with no sequela or evidence of recurrence. Author statement All authors have seen and approved the manuscript and contributed significantly to the work. Edison J. Cano: study design, image collections, writing. Cristina Corsini Campioli: literature review, writing. Andrew E. Rodriguez: writing. Mark J. Enzler: writing, proof-writing. Consent Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request. Financial disclosures None for all authors. Declaration of Competing Interest The authors report no declarations of interest.