A 28-year-old woman presents with severe sore throat, dysphagia, fever (39.5°C), and trismus for 3 days. Examination reveals a unilateral bulging of the soft palate with deviation of the uvula to the opposite side. Intraoral pus aspiration confirms peritonsillar abscess. What is the drug of choice for empirical antibiotic therapy?

Explanation

## Peritonsillar Abscess: Antibiotic Management **Key Point:** Peritonsillar abscess is a polymicrobial infection involving both aerobic (Streptococcus pyogenes, S. pneumoniae) and anaerobic organisms (Peptostreptococcus, Prevotella, Fusobacterium). Empirical therapy must cover both groups. ### Why Amoxicillin-Clavulanate? **High-Yield:** Amoxicillin-clavulanate is the first-line antibiotic for peritonsillar abscess because: - **Broad spectrum:** covers Group A Streptococcus (most common aerobe) and anaerobes - **β-lactamase inhibitor:** clavulanate protects amoxicillin from anaerobic β-lactamase production - **Excellent tissue penetration:** reaches therapeutic levels in pharyngeal tissues and pus - **Oral bioavailability:** suitable for outpatient management post-drainage **Clinical Pearl:** The standard regimen is amoxicillin-clavulanate 625 mg (500 mg amoxicillin + 125 mg clavulanate) three times daily for 7–10 days, or 875/125 mg twice daily. ### Comparative Antibiotic Spectrum | Antibiotic | Aerobic Coverage | Anaerobic Coverage | β-lactamase Resistant | First-Line? | |---|---|---|---|---| | **Amoxicillin-clavulanate** | ✓ (Strep, Pneumo) | ✓ (Peptostreptococcus, Prevotella) | ✓ | **YES** | | Cephalexin (1st gen) | ✓ (Strep, Pneumo) | ✗ (poor) | Partial | No | | Clindamycin | ✓ (Strep) | ✓ (anaerobes) | ✓ | Alternative only | | Azithromycin | ✓ (Strep) | ✗ (poor) | ✗ | No | **Mnemonic:** **PABA** = **P**enicillin + **A**naerobes = **B**est **A**ntibiotic → Amoxicillin-clavulanate (penicillin + β-lactamase inhibitor). ### Management Algorithm ```mermaid flowchart TD A[Peritonsillar Abscess Suspected]:::outcome --> B{Diagnosis Confirmed?}:::decision B -->|Yes| C[Drainage + Antibiotics]:::action C --> D[Amoxicillin-clavulanate 625 mg TDS]:::action D --> E[7-10 days oral therapy]:::action E --> F[Clinical resolution]:::outcome B -->|No| G[Supportive care + NSAIDs]:::action ``` **Warning:** Do NOT use cephalexin alone — it has poor anaerobic coverage and high failure rates. Clindamycin is reserved for penicillin-allergic patients.