What antibiotic is recommended for an adult with strep throat and an ear infection who has a penicillin allergy?

Antibiotic Treatment for Strep Throat and Ear Infection in Penicillin-Allergic Adults

Direct Recommendation

For an adult with strep throat and ear infection who has a penicillin allergy, prescribe cefixime 400 mg once daily for 10 days if the allergy is non-immediate (delayed rash), or clindamycin 300 mg three times daily for 10 days if the allergy is immediate/anaphylactic. 1, 2

Critical First Step: Determine Type of Penicillin Allergy

You must distinguish between immediate and non-immediate reactions before selecting an antibiotic. 2

• Immediate/anaphylactic reactions include anaphylaxis, angioedema, respiratory distress, hives, or urticaria occurring within 1 hour of penicillin administration 2
• Non-immediate reactions include delayed rashes appearing hours to days after administration 2
• Up to 10% cross-reactivity exists between penicillin and cephalosporins in patients with immediate hypersensitivity, making all beta-lactams unsafe in this group 3, 2

Treatment Algorithm

For Non-Immediate Penicillin Allergy (Delayed Rash)

First-line: Cefixime 400 mg once daily for 10 days 1

• Cefixime is FDA-approved for both otitis media and pharyngitis/tonsillitis caused by Streptococcus pyogenes, making it ideal for treating both conditions simultaneously 1
• The cross-reactivity risk with non-immediate penicillin allergy is only 0.1%, making cephalosporins safe in this population 2
• Alternative first-generation cephalosporins: Cephalexin 500 mg twice daily for 10 days or cefadroxil 1 gram once daily for 10 days 3, 4
• First-generation cephalosporins have strong, high-quality evidence for strep throat but are not FDA-approved for otitis media in adults, making cefixime the superior choice for dual coverage 3, 1

For Immediate/Anaphylactic Penicillin Allergy

First-line: Clindamycin 300 mg three times daily for 10 days 2, 4

• Clindamycin has strong, moderate-quality evidence and approximately 1% resistance rate among Group A Streptococcus in the United States 2
• Clindamycin is highly effective for both strep throat and ear infections, with superior efficacy even in chronic carriers 2
• Clindamycin provides excellent coverage for Streptococcus pyogenes and is effective against common ear infection pathogens 2

Second-line: Azithromycin 500 mg once daily for 5 days 3, 2

• Azithromycin is the only antibiotic requiring just 5 days due to its prolonged tissue half-life 3, 2
• However, macrolide resistance is 5-8% in the United States and varies geographically, making clindamycin more reliable 2
• Azithromycin has proven efficacy for both strep throat and otitis media 5, 6

Critical Treatment Duration Requirements

All antibiotics except azithromycin require a full 10-day course to achieve maximal pharyngeal eradication of Group A Streptococcus and prevent acute rheumatic fever. 3, 2

• Shortening the course by even a few days results in appreciable increases in treatment failure rates 2
• The primary goal is not just symptomatic improvement but prevention of acute rheumatic fever, which requires adequate bacterial eradication 2

Common Pitfalls to Avoid

Never use cephalosporins in patients with immediate/anaphylactic penicillin reactions due to the 10% cross-reactivity risk 3, 2

Do not prescribe shorter courses than recommended (except azithromycin's 5-day regimen) to prevent treatment failure and acute rheumatic fever 2, 4

Avoid assuming all penicillin-allergic patients cannot receive cephalosporins - only those with immediate/anaphylactic reactions should avoid them 2, 4

Do not use trimethoprim-sulfamethoxazole (Bactrim) for strep throat due to high resistance rates (50%) and lack of efficacy against Group A Streptococcus 2

Adjunctive Therapy

Consider acetaminophen or NSAIDs (ibuprofen) for moderate to severe symptoms or high fever 2

Avoid aspirin in children due to Reye syndrome risk, though this is less relevant for adults 2

Do not prescribe corticosteroids as adjunctive therapy 2

Post-Treatment Considerations

Routine follow-up throat cultures or rapid antigen tests are not recommended for asymptomatic patients who have completed therapy 2

Patients are generally non-contagious after 24 hours of antibiotic therapy 7