A 5-year-old child with sickle cell disease is being started on prophylactic therapy to prevent life-threatening infections. Which antibiotic is the drug of choice for this indication?

Question

Accepted Answer

A. Penicillin V. ## Prophylactic Antibiotic in Sickle Cell Disease

**Key Point:** Penicillin V is the first-line prophylactic agent against encapsulated organisms (especially *Streptococcus pneumoniae*) in sickle cell patients, particularly children <5 years.

### Rationale for Penicillin Prophylaxis

**High-Yield:** Sickle cell patients have functional asplenia due to:
1. Repeated splenic infarction from vaso-occlusion
2. Loss of opsonizing antibodies and complement-mediated immunity
3. Impaired clearance of encapsulated bacteria

This results in a 300–400-fold increased risk of invasive pneumococcal disease.

### Penicillin V Dosing & Duration

| Age Group | Dose | Route | Duration |
|---|---|---|---|
| <5 years | 125 mg BID | PO | Until age 5 years (minimum) |
| ≥5 years | 250 mg BID | PO | Lifelong or until splenectomy |
| Penicillin-allergic | Erythromycin 250 mg BID | PO | Same duration |

**Clinical Pearl:** Penicillin prophylaxis is recommended from diagnosis (or age 2 months) and continued lifelong in most patients. Compliance is critical — missed doses increase infection risk.

### Vaccination Adjunct

Penicillin prophylaxis is NOT a substitute for:
- Pneumococcal conjugate vaccine (PCV13) at 2, 4, 6, 12–15 months
- Pneumococcal polysaccharide vaccine (PPSV23) at ≥2 years
- Annual influenza vaccine
- Meningococcal vaccine

**Warning:** Do NOT discontinue penicillin even after vaccination — prophylaxis must continue because vaccine response is suboptimal in asplenic patients.

### Why Penicillin V (Not Amoxicillin)

- Penicillin V is acid-stable and reliably absorbed orally
- Amoxicillin has similar coverage but penicillin V is the traditional choice in pediatric sickle cell guidelines
- Both are acceptable; penicillin V is preferred by convention

[cite:Harrison 21e Ch 104; Park 26e Ch 18]

Answer

B. Azithromycin

Answer

C. Amoxicillin-clavulanate

Answer

D. Cephalexin

A 5-year-old child with sickle cell disease is being started on prophylactic therapy to prevent life-threatening infections. Which antibiotic is the drug of choice for this indication?

Explanation

Prophylactic Antibiotic in Sickle Cell Disease

Rationale for Penicillin Prophylaxis

Penicillin V Dosing & Duration

Vaccination Adjunct

Why Penicillin V (Not Amoxicillin)

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Age Group	Dose	Route	Duration
<5 years	125 mg BID	PO	Until age 5 years (minimum)
≥5 years	250 mg BID	PO	Lifelong or until splenectomy
Penicillin-allergic	Erythromycin 250 mg BID	PO	Same duration