A patient with Lyme disease presents with migratory polyarthritis 4 months after the initial skin rash. Serology shows positive ELISA confirmed by Western blot (IgG bands to OspC and p41). First-line treatment for Lyme arthritis is:

• A Benzathine penicillin G IM single dose
• B IV ceftriaxone 2 g/day for 14 days
• C Azithromycin 500 mg/day for 5 days
• D Doxycycline 100 mg BD for 28 days (oral) ✓

Explanation

Lyme arthritis (late disseminated Lyme disease) is treated with oral doxycycline 100 mg BD for 28 days as first-line; amoxicillin 500 mg TID for 28 days is an alternative. IV ceftriaxone is reserved for refractory Lyme arthritis or when oral therapy fails. Single-dose benzathine penicillin is used only for early syphilis. Azithromycin is inferior to doxycycline for Lyme disease and is not recommended for late-stage disease.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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