Answer: E - This patient presents with symptoms suggestive of acute mastoiditis, namely fever, painful edema of the external auditory canal with protrusion of the auricle and obliteration of the postauricular crease, hearing loss, and a bulging, red TM, as well as the involvement of mastoid air cells on CT. In adult patients presenting with acute mastoiditis, referral and admission to the hospital and empiric treatment with IV vancomycin or nafcillin is indicated, followed by a consult with ENT for immediate tympanocentesis/myringotomy.
Oral cefuroxime is only effective for treating otitis media and insufficient for acute mastoiditis. Outpatient management is not appropriate for this patient - they need IV antibiotics. Orbital CT in contrast, has little further diagnostic value in this context.