What are the first and second line treatments for an adult patient with an ear or sinus infection, without significant medical history or allergies?

First and Second-Line Treatment for Ear/Sinus Infection

For acute bacterial sinusitis in adults without allergies, amoxicillin-clavulanate (875 mg/125 mg twice daily) is the preferred first-line treatment for 5-10 days, with respiratory fluoroquinolones (levofloxacin or moxifloxacin) reserved as second-line therapy after treatment failure. 1, 2

Confirming Bacterial Infection Before Treatment

Before prescribing antibiotics, confirm one of three diagnostic patterns 2, 3:

• Persistent symptoms: Nasal discharge or cough lasting ≥10 days without improvement 3
• Severe onset: Fever ≥39°C with purulent nasal discharge for ≥3 consecutive days 2
• "Double sickening": Worsening symptoms after initial improvement from a viral upper respiratory infection 2

Critical pitfall: 98-99.5% of acute rhinosinusitis is viral and resolves spontaneously within 7-10 days—do not prescribe antibiotics for symptoms lasting less than 10 days unless severe features are present. 4, 3

First-Line Antibiotic Selection

Standard First-Line Treatment

Amoxicillin-clavulanate 875 mg/125 mg twice daily for 5-10 days is the preferred first-line agent because it provides coverage against β-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis, which have become increasingly prevalent. 1, 2

Plain amoxicillin 500 mg twice daily (mild disease) or 875 mg twice daily (moderate disease) remains acceptable for uncomplicated cases without recent antibiotic exposure. 4, 2

High-dose amoxicillin-clavulanate (2 g twice daily) should be used when 1:

• Recent antibiotic use within the past month
• Moderate to severe symptoms
• Age >65 years
• Comorbid conditions (diabetes, chronic cardiac/hepatic/renal disease)
• Immunocompromised state
• High local prevalence (>10%) of penicillin-resistant Streptococcus pneumoniae

Treatment Duration

Treat for 5-10 days, or until symptom-free for 7 days 1, 4, 2. Shorter 5-7 day courses have comparable efficacy with fewer side effects compared to traditional 10-14 day regimens. 4

Penicillin-Allergic Patients

Non-Anaphylactic Penicillin Allergy

For patients with non-severe penicillin allergy (rash, mild reactions), second- or third-generation cephalosporins are safe and effective 1, 2:

• Cefuroxime-axetil (second-generation) 4, 2
• Cefpodoxime-proxetil (third-generation, superior activity against H. influenzae) 4, 2
• Cefdinir (third-generation) 4, 2

The risk of cross-reactivity between penicillins and second/third-generation cephalosporins is negligible. 4

Severe Beta-Lactam Allergy (Anaphylaxis)

For documented Type I hypersensitivity, use 1, 2:

• Doxycycline 100 mg once daily for 10 days 1, 2
• Levofloxacin 500 mg once daily for 10-14 days 1, 2
• Moxifloxacin 400 mg once daily for 10 days 1

Critical warning: Doxycycline has limited activity against H. influenzae with a predicted bacteriologic failure rate of 20-25%, making it suboptimal when better alternatives exist. 4

What NOT to Use in Penicillin-Allergic Patients

Azithromycin and other macrolides are explicitly contraindicated as first-line therapy due to resistance rates exceeding 20-25% for both S. pneumoniae and H. influenzae. 1, 4, 2

Trimethoprim-sulfamethoxazole should not be used due to high resistance rates (50% for S. pneumoniae, 27% for H. influenzae). 4

Second-Line Treatment After First-Line Failure

When to Switch Antibiotics

Reassess patients at 3-5 days: If no improvement, switch antibiotics or re-evaluate diagnosis. 1, 4, 2

At 7 days: Confirm diagnosis of acute bacterial sinusitis if symptoms persist or worsen. 1, 4

Second-Line Antibiotic Options

For patients who fail amoxicillin-clavulanate, switch to a respiratory fluoroquinolone 1, 4, 2:

• Levofloxacin 500 mg once daily for 10-14 days (preferred) 4, 2
• Moxifloxacin 400 mg once daily for 10 days 4, 2

These agents provide 90-92% predicted clinical efficacy with excellent coverage against drug-resistant S. pneumoniae, β-lactamase-producing H. influenzae, and M. catarrhalis. 4, 2

Alternative second-line option: High-dose amoxicillin-clavulanate (2 g/250 mg twice daily) if not already tried. 4

Parenteral Option for Treatment Failure

Ceftriaxone 1-2 g IM or IV once daily for 5 days is indicated when 5:

• Patient cannot tolerate oral medications (vomiting, severe illness)
• Moderate-to-severe disease with recent antibiotic exposure
• Oral antibiotics have failed after 72 hours

Ceftriaxone achieves 90-92% predicted clinical efficacy and ensures adequate drug levels regardless of GI absorption. 5

Adjunctive Therapies

Intranasal Corticosteroids

Intranasal corticosteroids (mometasone, fluticasone, or budesonide twice daily) are strongly recommended as adjunct to antibiotic therapy in both acute and chronic sinusitis. 1, 4, 2 They reduce mucosal inflammation, improve symptom resolution, and may decrease antibiotic use. 4

Oral Corticosteroids

Short-term oral corticosteroids (typically 5 days) may be considered for 4, 2:

• Patients who fail to respond to initial antibiotic treatment
• Marked mucosal edema
• Nasal polyposis

Critical warning: Never give systemic corticosteroids without antibiotics when bacterial sinusitis is suspected, as this may suppress the immune response and allow bacterial proliferation. 4

Symptomatic Relief

Offer the following for symptom management 4, 2:

• Analgesics (acetaminophen, NSAIDs) for pain and fever
• Saline nasal irrigation for symptomatic relief and mucus removal
• Decongestants (systemic or topical) as needed

Watchful Waiting Option

For adults with uncomplicated acute bacterial sinusitis, watchful waiting without immediate antibiotics is an appropriate initial strategy when reliable follow-up can be assured. 1, 2 Instruct patients to start antibiotics only if no improvement occurs by 7 days or if symptoms worsen at any time. 4

Approximately 90% of patients with acute rhinosinusitis improve naturally within 7-15 days without antibiotic treatment. 4 The number needed to treat with antibiotics is 10-15 to get one additional person better after 7-15 days. 4

Critical Pitfalls to Avoid

Do not prescribe antibiotics for viral rhinosinusitis lasting <10 days, as this contributes to antimicrobial resistance without clinical benefit. 4, 2

Do not use fluoroquinolones as routine first-line therapy—reserve them for treatment failures, severe disease, or penicillin-allergic patients to prevent resistance development. 1, 4, 2

Do not use first-generation cephalosporins (cephalexin) for sinusitis due to inadequate coverage against H. influenzae (nearly 50% of strains are β-lactamase producing). 4

Do not use clindamycin as monotherapy for sinusitis, as it lacks activity against H. influenzae and M. catarrhalis and will fail in approximately 30-40% of cases. 4

Ensure adequate treatment duration (minimum 5 days, typically 7-10 days) to prevent relapse. 1, 4, 2

When to Refer to a Specialist

Refer patients to otolaryngology or allergist-immunologist for 4, 2:

• Symptoms refractory to two courses of appropriate antibiotics
• Recurrent sinusitis (≥3 episodes per year)
• Suspected complications (orbital cellulitis, meningitis, periorbital cellulitis)
• Need for sinus aspiration/culture in immunocompromised patients
• Evaluation for underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities