In a 26-year-old adult with a documented allergy to Augmentin (amoxicillin-clavulanate) and a suspected left ear infection likely caused by Streptococcus pneumoniae, what oral antibiotic should I prescribe?

Antibiotic Selection for Augmentin-Allergic Patient with Ear Infection and Possible Strep

For a 26-year-old with Augmentin allergy, suspected left ear infection, and possible strep throat, prescribe cefdinir 300 mg twice daily for 7 days as the preferred first-line alternative, or azithromycin 500 mg on day 1 followed by 250 mg daily for 4 more days if the patient has a documented Type I (anaphylactic) penicillin allergy. 1

Understanding the Allergy Profile

The nature of the Augmentin allergy determines your antibiotic choice:

• Non-severe penicillin allergy (rash, mild GI upset): Second- or third-generation cephalosporins are safe, with cross-reactivity rates of only 0.1%—far lower than the historically cited 10% 1, 2
• Type I hypersensitivity (anaphylaxis, angioedema, urticaria): All beta-lactams including cephalosporins are contraindicated; macrolides become the only safe oral option 1

First-Line Recommendation: Cefdinir (for Non-Severe Allergy)

Cefdinir is the preferred cephalosporin alternative because it offers:

• Adult dosing: 300 mg twice daily (or 600 mg once daily) for 7 days 1
• Superior tolerability: Only 10-13% diarrhea rate versus ≈35% with Augmentin 1
• Excellent coverage: Reliably covers beta-lactamase-producing H. influenzae and M. catarrhalis (common ear pathogens), plus S. pneumoniae and S. pyogenes (strep throat) 1, 2
• Convenient dosing: Once-daily option improves compliance 1

Alternative Cephalosporins (if cefdinir unavailable)

• Cefuroxime axetil: 500 mg twice daily 1
• Cefpodoxime: 200-400 mg twice daily 1

Second-Line: Macrolides (for True Type I Allergy)

If the patient has documented anaphylaxis to penicillins:

• Azithromycin (Z-Pak): 500 mg day 1, then 250 mg daily × 4 days 3
• Clarithromycin: 500 mg twice daily × 7-10 days 1

Critical Limitations of Macrolides

• Bacterial failure rates of 20-25% due to pneumococcal macrolide resistance exceeding 40% in the U.S. 1, 2
• Should NOT be first-line unless cephalosporins are absolutely contraindicated 4, 1
• The FDA label explicitly states azithromycin is "often effective" but warns that "some strains are resistant" and susceptibility testing should be performed 3

What NOT to Prescribe

Avoid these antibiotics entirely:

• Trimethoprim-sulfamethoxazole (Bactrim): 50% resistance in S. pneumoniae, 20-25% bacterial failure rate 4, 1
• Fluoroquinolones (levofloxacin, moxifloxacin): Reserve for treatment failures or severe disease; inappropriate as first-line due to resistance concerns and side-effect profile 1

Treatment Duration and Follow-Up

• Standard duration: 5-7 days for uncomplicated adult ear infections and strep throat 1
• Reassess at 48-72 hours if symptoms worsen or fail to improve 1, 2
• If treatment fails on cefdinir: Switch to a respiratory fluoroquinolone (levofloxacin 750 mg daily × 5 days) or consider IM ceftriaxone 1-2 grams daily × 1-3 days 1, 2

Common Pitfalls to Avoid

• Do not use cefdinir if the patient had anaphylaxis, angioedema, or urticaria to Augmentin—cross-reactivity risk exists despite being low 1, 2
• Do not prescribe macrolides as first-line when cephalosporins are safe; you're accepting a 20-25% failure rate unnecessarily 1
• Do not assume all "penicillin allergies" are true Type I reactions—most patients labeled "allergic" can safely receive cephalosporins 1, 2
• Isolated tympanic membrane redness without effusion does not require antibiotics 1

Pain Management (Essential Regardless of Antibiotic Choice)

• Initiate ibuprofen 400-600 mg every 6-8 hours or acetaminophen 650-1000 mg every 6 hours immediately 1, 2
• Antibiotics provide no symptomatic relief in the first 24 hours; analgesics are the primary pain treatment 1, 2

Addressing the Strep Component

• If strep pharyngitis is confirmed (rapid strep test or culture), the same antibiotics cover both conditions 1, 3
• Penicillin remains the gold standard for strep throat, but cefdinir and azithromycin are FDA-approved alternatives 3, 5
• 10-day courses are traditional for strep throat to prevent rheumatic fever, though 5-7 days of cefdinir or azithromycin are FDA-approved 3, 5