In a patient with acute bacterial sinusitis symptoms persisting >10 days and worsening, which antibiotic should be prescribed?

Antibiotic Selection for Persistent Acute Bacterial Sinusitis

For a patient with acute bacterial sinusitis symptoms persisting beyond 10 days and worsening, prescribe amoxicillin-clavulanate 875 mg/125 mg twice daily for 5–10 days as first-line therapy, providing 90–92% predicted clinical efficacy against the major sinusitis pathogens. 1

Confirming the Diagnosis Before Prescribing

• Acute bacterial rhinosinusitis (ABRS) is diagnosed when any one of three clinical patterns is present: (1) persistent symptoms ≥10 days without improvement (purulent nasal discharge plus obstruction or facial pain/pressure), (2) severe symptoms ≥3–4 consecutive days (fever ≥39°C with purulent discharge and facial pain), or (3) "double sickening" (initial improvement followed by worsening within 10 days). 2

• Approximately 98–99.5% of acute rhinosinusitis cases are viral and resolve spontaneously within 7–10 days; antibiotics should not be prescribed for symptoms <10 days unless severe features are present. 2, 1

• The patient's presentation of persistent symptoms beyond 10 days with worsening meets the diagnostic criteria for ABRS and mandates antibiotic therapy rather than continued observation. 2, 1

First-Line Antibiotic Regimen

• Amoxicillin-clavulanate 875 mg/125 mg orally twice daily for 5–10 days (or until symptom-free for 7 consecutive days, typically 10–14 days total) is the preferred first-line regimen for adults with confirmed ABRS. 2, 1

• The clavulanate component is essential because 30–40% of Haemophilus influenzae and 90–100% of Moraxella catarrhalis produce β-lactamase, rendering plain amoxicillin ineffective against these organisms. 1

• Recent evidence supports shorter 5–7 day courses as equally effective with fewer adverse effects compared with traditional 10-day regimens. 1

When to Use High-Dose Amoxicillin-Clavulanate

• High-dose amoxicillin-clavulanate (2 g/125 mg twice daily) should be used when any of the following risk factors for resistant organisms are present: recent antibiotic use (past 4–6 weeks), age >65 years, daycare exposure, moderate-to-severe symptoms, comorbidities (diabetes, chronic cardiac/hepatic/renal disease), or immunocompromised state. 1

Alternatives for Penicillin-Allergic Patients

Non-Severe (Non-Type I) Penicillin Allergy

• For patients with non-severe penicillin allergy (e.g., mild rash), prescribe a second- or third-generation cephalosporin (cefuroxime-axetil, cefpodoxime-proxetil, cefdinir, or cefprozil) for 10 days; cross-reactivity with penicillins is <1%. 2, 1

Severe (Type I/Anaphylactic) Penicillin Allergy

• For patients with severe (type I) penicillin allergy, use a respiratory fluoroquinolone: levofloxacin 500 mg once daily for 10–14 days or moxifloxacin 400 mg once daily for 10 days, both achieving 90–92% predicted efficacy against multidrug-resistant Streptococcus pneumoniae and β-lactamase-producing organisms. 2, 1, 3

• Fluoroquinolones should be reserved for severe penicillin allergy or documented treatment failure to limit resistance development. 1

Essential Adjunctive Therapies (Add to All Patients)

• Intranasal corticosteroids (mometasone, fluticasone, or budesonide) twice daily significantly reduce mucosal inflammation and speed symptom resolution; this recommendation is supported by strong evidence from multiple randomized controlled trials. 2, 1

• Saline nasal irrigation 2–3 times daily provides symptomatic relief and enhances mucus clearance. 2, 1

• Analgesics (acetaminophen or ibuprofen) are recommended for pain and fever control. 2, 1

Monitoring and Reassessment Protocol

• Reassess at 3–5 days after initiating therapy: if there is no clinical improvement (persistent purulent drainage, unchanged facial pain, or worsening), switch promptly to high-dose amoxicillin-clavulanate (2 g/125 mg twice daily) or a respiratory fluoroquinolone (levofloxacin or moxifloxacin). 1

• Reassess at 7 days: persistent or worsening symptoms require (1) confirmation of ABRS diagnosis, (2) exclusion of complications (orbital cellulitis, meningitis, intracranial abscess), (3) imaging only if complications are suspected, and (4) referral to an otolaryngologist. 2, 1

• Expected timeline of recovery: noticeable improvement should occur within 3–5 days of appropriate therapy, with complete resolution by 10–14 days or when the patient is symptom-free for 7 consecutive days. 1

Antibiotics to Avoid in ABRS

• Macrolides (azithromycin, clarithromycin) are discouraged due to 20–25% resistance in S. pneumoniae and H. influenzae. 1

• Trimethoprim-sulfamethoxazole shows ≈50% resistance in S. pneumoniae and ≈27% in H. influenzae. 1

• First-generation cephalosporins (e.g., cephalexin) are inadequate because ≈50% of H. influenzae strains produce β-lactamase. 1

When to Refer to Otolaryngology

• Immediate referral is indicated for any of the following: (1) no improvement after 7 days of appropriate second-line antibiotic therapy, (2) worsening symptoms at any point, (3) suspected complications (severe headache, visual changes, periorbital swelling/erythema, proptosis, diplopia, altered mental status, cranial nerve deficits), or (4) recurrent sinusitis (≥3 episodes per year) requiring evaluation for underlying allergic, immunologic, or anatomic factors. 1

Critical Pitfalls to Avoid

• Do not prescribe antibiotics for symptoms <10 days unless severe features (fever ≥39°C with purulent discharge for ≥3 consecutive days) are present. 2, 1

• Avoid routine imaging (X-ray or CT) for uncomplicated ABRS; up to 87% of viral upper-respiratory infections show sinus abnormalities on imaging, leading to unnecessary interventions. 2, 1

• Ensure adequate treatment duration (≥5 days for adults) to prevent relapse. 1

• Gastrointestinal adverse effects with amoxicillin-clavulanate are common: diarrhea in 40–43% of patients and severe diarrhea in 7–8%. 1