What antibiotic can be given to a patient with a history of strep throat 6 months ago, who was previously treated with co-amoxiclav (amoxicillin-clavulanate), and is now experiencing a recurrence of strep throat?

Treatment of Recurrent Strep Throat After Co-Amoxiclav

For a patient with recurrent strep throat 6 months after treatment with co-amoxiclav, you should prescribe clindamycin 20-30 mg/kg/day divided three times daily (maximum 300 mg/dose) for 10 days, as this agent has superior eradication rates in recurrent or treatment-failure scenarios. 1

Primary Treatment Recommendation

The 2012 IDSA guidelines specifically identify clindamycin and amoxicillin-clavulanate as agents that "may be beneficial because they have been shown to yield high rates of pharyngeal eradication of streptococci" in recurrent cases 1. Given that this patient already received co-amoxiclav (amoxicillin-clavulanate) 6 months ago, clindamycin is the preferred choice 1.

Clindamycin Dosing

• Adults: 300 mg orally three times daily for 10 days 1
• Children: 20-30 mg/kg/day divided three times daily (maximum 300 mg/dose) for 10 days 1
• This regimen has strong, high-quality evidence for treating recurrent GAS pharyngitis 1

Alternative Options (If Clindamycin Cannot Be Used)

If clindamycin is contraindicated or not tolerated, consider these alternatives in order of preference:

First-Generation Cephalosporin

• Cephalexin: 20 mg/kg twice daily (maximum 500 mg/dose) for 10 days 1
• Use only if the patient does not have immediate/anaphylactic penicillin allergy 1

High-Dose Amoxicillin-Clavulanate

• 40 mg amoxicillin/kg/day divided three times daily (maximum 2000 mg amoxicillin/day) for 10 days 1
• This is a higher dose than typically used for initial treatment 1
• Has strong, moderate evidence for carrier eradication 1

Macrolides (Less Preferred)

• Clarithromycin: 7.5 mg/kg twice daily (maximum 250 mg/dose) for 10 days 1
• Azithromycin: 12 mg/kg once daily (maximum 500 mg) for 5 days 1
• Important caveat: Macrolide resistance is common and varies geographically 1, 2
• In one study, clarithromycin failed to eradicate 81-86% of resistant isolates 2

Critical Clinical Distinction: True Recurrence vs. Carrier State

Before treating, you must differentiate between:

True Recurrent Infection

• Presents with classic strep symptoms: fever, tonsillar exudates, tender anterior cervical lymphadenopathy, absence of cough 1, 3
• Positive rapid antigen test or culture 1
• Requires antibiotic treatment 1, 3

Chronic Carrier with Viral Infection

• Up to 20% of school-aged children are asymptomatic GAS carriers 1, 3
• Carriers experiencing viral pharyngitis present with: cough, rhinorrhea, congestion, hoarseness 1, 3
• Carriers are at low risk for complications and do not spread GAS to contacts 1, 3
• Do not treat carriers unless special circumstances exist 1

When to Consider Carrier-State Treatment

The IDSA identifies specific situations where carrier eradication may be warranted 1:

1. Community outbreak of acute rheumatic fever, post-streptococcal glomerulonephritis, or invasive GAS 1
2. Outbreak in closed/semi-closed community (e.g., military barracks, boarding school) 1
3. Personal or family history of acute rheumatic fever 1
4. Family with excessive anxiety about GAS infections 1
5. Tonsillectomy being considered solely because of carrier state 1

Evidence Supporting Clindamycin Superiority

Research demonstrates clindamycin's effectiveness in recurrent cases:

• 92% eradication rate with clindamycin vs. 55% with penicillin plus rifampin in chronic carriers 4
• In patients with treatment failure after penicillin, clindamycin protected against recurrence for at least 3 months 5
• Only 3/26 patients (12%) had positive cultures after clindamycin vs. 15/22 (68%) after continued penicillin 5

Common Pitfalls to Avoid

Do NOT Use These Antibiotics

• Tetracyclines, sulfonamides, trimethoprim-sulfamethoxazole, or older fluoroquinolones (ciprofloxacin) are not effective against GAS 3, 6

Do NOT Routinely Test After Treatment

• Post-treatment cultures are not recommended for asymptomatic patients who completed therapy 1, 3
• Testing should only occur if symptoms persist or in special high-risk circumstances 1, 3

Do NOT Treat Asymptomatic Household Contacts

• Routine testing and treatment of contacts is not recommended 1
• Consider only if multiple family members have repeated documented infections suggesting "ping-pong" transmission 3

Compliance Considerations

Since this is a recurrence 6 months after initial treatment, compliance with the original regimen is unlikely to be the issue 1. However, for the current treatment:

• Clindamycin requires three-times-daily dosing for 10 days 1
• If compliance is a concern, consider intramuscular benzathine penicillin G (600,000 U for <27 kg; 1,200,000 U for ≥27 kg) as a single dose, though this is less effective than clindamycin for recurrent cases 1

Follow-Up Recommendations

• No routine post-treatment testing unless symptoms persist or recur 1, 3
• If multiple recurrences continue over months to years, consider that the patient may be a chronic carrier experiencing repeated viral infections 1, 3
• For truly recurrent infections, evaluate household contacts for possible source of reinfection 3