Which antibiotic is specifically used to address acute leptospirosis?

• A. IV penicillin
• B. Oral amoxicillin only
• C. Erythromycin
• D. Metronidazole

Answer: (A)

Treating acute leptospirosis hinges on rapidly delivering an antibiotic that effectively clears Leptospira during the early, bacteremic phase. IV penicillin G is the best choice because it achieves high serum and tissue levels quickly, directly targeting the organism and reducing the duration of illness and the risk of progression to severe complications like Weil’s disease (jaundice, kidney failure). While other antibiotics such as doxycycline, amoxicillin, or oral agents can be used in milder cases, they are not as reliably effective in acute, severe disease. Erythromycin and metronidazole are not first-line options for this infection due to limited evidence of efficacy. Therefore, intravenous penicillin is the most appropriate and best-supported option for acute leptospirosis.