What is the empiric treatment for peritonsillar abscess?

Empiric Treatment for Peritonsillar Abscess

Empiric antibiotic therapy for peritonsillar abscess should target both Group A Streptococcus and oral anaerobes, with penicillin plus metronidazole or clindamycin monotherapy as first-line options, combined with immediate drainage of the abscess.

Drainage Procedure

• Drainage is the cornerstone of treatment and must be performed immediately upon diagnosis, either by needle aspiration or incision and drainage 1, 2
• Needle aspiration is less painful procedurally but may have higher recurrence rates (RR 3.74,95% CI 1.63-8.59) compared to incision and drainage 2
• For patients with first presentation and no history of recurrent tonsillitis, needle aspiration is reasonable; consider incision and drainage for recurrent cases 3

Antibiotic Selection

First-Line Regimens

Penicillin plus metronidazole is the recommended first-line combination because peritonsillar abscesses are polymicrobial infections involving both aerobic streptococci and anaerobic bacteria 4, 1

• Penicillin G 2-4 million units IV every 4-6 hours 5
• Plus metronidazole 500 mg every 8 hours 4

Clindamycin monotherapy is an excellent alternative as it covers both Group A Streptococcus and oral anaerobes in a single agent 4, 1

• Clindamycin 600-900 mg IV every 8 hours 6
• Effective against both aerobic and anaerobic pathogens commonly isolated from peritonsillar abscesses 4

Microbiologic Rationale

• Streptococcus pyogenes (Group A Streptococcus) is the most common aerobic pathogen, isolated in approximately 50% of cases 3, 7
• Staphylococcus aureus is the second most common aerobe, found in approximately 20% of cases, and is frequently penicillin-resistant 7
• Anaerobic bacteria play a significant role and are present in mixed infections 4
• Polymicrobial infections with 2-3 organisms are typical 1

Alternative Regimens

If penicillin plus metronidazole or clindamycin cannot be used:

• Amoxicillin-clavulanate 875/125 mg orally twice daily (for outpatient transition) provides coverage against both aerobes and anaerobes 6
• Ampicillin-sulbactam 1.5-3.0 g IV every 6 hours for hospitalized patients 6

Penicillin Allergy

For patients with severe penicillin hypersensitivity:

• Clindamycin remains the best option as it is not cross-reactive 6, 4
• Alternatively, a fluoroquinolone (levofloxacin 750 mg daily or moxifloxacin 400 mg daily) plus metronidazole 6

Important Clinical Considerations

When to Broaden Coverage

• If Staphylococcus aureus is suspected or isolated, ensure coverage with cloxacillin, cefazolin, or clindamycin, as all S. aureus isolates in one study were penicillin-resistant 7
• If initial therapy fails after 48-72 hours, consider broader spectrum coverage with clindamycin or amoxicillin-clavulanate 4

Prognostic Indicators

• Presence of Streptococcus pyogenes alone in aspirate is associated with favorable prognosis with puncture and antibiotics 3
• Mixed aerobic-anaerobic flora without S. pyogenes may require incision and drainage rather than aspiration alone 3

Adjunctive Therapy

• Corticosteroids may reduce symptoms and speed recovery, though this is based on limited evidence 1
• Maintain hydration and provide adequate pain control 1

Common Pitfalls to Avoid

• Do not use penicillin monotherapy without anaerobic coverage, as this will miss a significant portion of the polymicrobial flora 4
• Routine culture is unnecessary on initial presentation, but empiric therapy must cover both aerobes and anaerobes 4
• Do not delay drainage while waiting for antibiotic effect; drainage is essential and antibiotics are adjunctive 1, 2
• Most patients can be managed in the outpatient setting after drainage; hospitalization is reserved for airway compromise, dehydration, or inability to tolerate oral intake 1