A rice-field worker in Kerala develops fever, myalgia, conjunctival suffusion, and jaundice with renal failure (Weil's disease) after flooding. MAT (Microscopic Agglutination Test) titre to Leptospira interrogans is 1:800. The first-line antibiotic for severe leptospirosis is:

• A Doxycycline 100 mg BD for 7 days (oral)
• B Oral azithromycin 500 mg/day for 5 days
• C Oral ampicillin 500 mg QID for 7 days
• D IV penicillin G 1.5 MU every 6 hours for 7 days or IV ceftriaxone 1 g/day ✓

Explanation

Severe leptospirosis (Weil's disease: jaundice, renal failure, haemorrhage) requires parenteral antibiotics — IV penicillin G (1.5 MU 6-hourly) or IV ceftriaxone (1 g/day) for 7 days. Oral doxycycline (100 mg BD × 7 days) is used for mild-to-moderate leptospirosis and as post-exposure prophylaxis. MAT with titre ≥1:400 combined with compatible clinical features is diagnostic. Early antibiotic therapy reduces duration and severity even in severe disease.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.