Cervicofacial actinomycosis — DTM&H MCQ

Correct answer: E — High-dose IV penicillin 4-6 weeks then oral amoxicillin 6-12 months

The correct answer is E, high-dose IV penicillin for 4 to 6 weeks then oral amoxicillin for 6 to 12 months. This is cervicofacial actinomycosis caused by Actinomyces israelii, a filamentous branching gram-positive anaerobe that classically produces sulphur granules in chronic discharging sinuses of the jaw and neck. Because Actinomyces forms dense, poorly vascularised fibrotic masses, prolonged high-dose penicillin is required to achieve adequate tissue penetration before stepping down to oral therapy for many months to prevent relapse. <cite index="4-1">The treatment of actinomycosis comprises a high dose of antibiotics (18-24 million units a day) of intravenous penicillin G over two to six weeks, followed by oral penicillin V at a dose of 2-4 g/day for six to 12 months.</cite> This prolonged regimen distinguishes actinomycosis management from other granulomatous or fungal infections that mimic it clinically. Why the other options are wrong: C. Co-trimoxazole for 3 months: this is the regimen for actinomycetoma caused by Nocardia species, which are filamentous but weakly acid-fast (partially Gram-positive), not for true Actinomyces infection. A. Surgical excision alone: surgery may be adjunctive for debulking necrotic sinus tracts but antibiotics are the cornerstone of cure; excision alone leaves residual organisms in fibrotic tissue and risks relapse. D. Itraconazole for 12 months: this targets eumycetoma from fungal agents such as Madurella, not a bacterial branching organism; antifungals have no activity against Actinomyces. B. Rifampicin and isoniazid for 6 months: this is antitubercular therapy; although TB can cause cervical lymphadenitis, it does not produce sulphur granules or gram-positive branching filaments on histology. Key point: sulphur granules plus gram-positive branching filaments equals Actinomyces israelii, treated with prolonged high-dose penicillin then oral amoxicillin, never confused with the acid-fast Nocardia or fungal mycetoma agents.

Reference: GPnotebook, Actinomycosis: Treatment, https://gpnotebook.com/pages/infectious-disease/actinomycosis/treatment