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Brain Abscess — SCE Infectious Diseases MCQ

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ModerateCNS InfectionBrain AbscessSCE Infectious Diseases

A 72-year-old woman with type 2 diabetes presents with 5 days of confusion and fever. She recently completed antibiotics for a urinary tract infection. CT brain shows a 3 cm ring-enhancing lesion in the right temporal lobe with surrounding oedema. Blood cultures are sterile. What is the most likely causative organism group?

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Correct answer: B — Mixed anaerobes and streptococci

Brain abscesses in immunocompetent patients most commonly contain mixed flora including anaerobes (Bacteroides, Prevotella, Fusobacterium) and streptococci (particularly S. anginosus group/milleri). The temporal lobe location may suggest spread from otogenic or dental sources. Empirical treatment is typically IV Ceftriaxone plus IV Metronidazole. S. aureus is more common with post-traumatic or post-neurosurgical abscesses. Toxoplasma would be expected in advanced HIV.

Reference: BSAC/BIA 2017 – Management of brain abscess; NICE CKS 2024 – Brain abscess