Capnocytophaga spp. brain abscess in an immunocompetent host: problems in antimicrobial chemotherapy and literature review.

The fourth case report of a brain abscess due to the fastidious Gram-negative organism Capnocytophaga spp. is described and discussed on the grounds of clinical, microbiological, and therapeutic evidence. A probable origin from a cat bite and/or an underlying severe mandibulary granuloma is suspected. Due to lack of clinical and neuroradiological response to neurosurgery and a combination of imipenem-amikacin-clindamycin-fluconazole, second-line empiric llnezolid treatment proved rapidly successful, in the absence of further microbial isolations. In vitro antimicrobial susceptibility testing is often unpredictable for Capnocytophaga spp., and agents usually active on Gram-positive organisms may also be effective, both in vitro and in vivo. Due to its favorable brain penetration and its dual mode of administration, linezolid may be an alternative option for patients with multiple risk factors, brain abscess of suspected polymicrobial origin, and lack of response to empiric or culture-driven therapeutic attempts.