In a healthy adult who completed a 5‑day course of Augmentin (amoxicillin‑clavulanate) for acute sinusitis but still has persistent symptoms, what is the appropriate next step in management?

Management of Persistent Sinusitis After Completing Augmentin

Switch to a Respiratory Fluoroquinolone Immediately

For a healthy adult who completed 5 days of Augmentin without improvement, switch to levofloxacin 500 mg once daily or moxifloxacin 400 mg once daily for 10 days. These respiratory fluoroquinolones provide 90–92% predicted clinical efficacy against drug-resistant Streptococcus pneumoniae and β-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis, making them the optimal second-line choice after amoxicillin-clavulanate failure. 1, 2, 3

Why the Initial Treatment Failed

• After 5 days of appropriate antibiotic therapy, most patients should show noticeable improvement; lack of any improvement indicates treatment failure and warrants an immediate antibiotic switch rather than extending the current regimen. 1, 4
• The most likely causes of Augmentin failure are β-lactamase-producing organisms (H. influenzae or M. catarrhalis) that were inadequately covered, drug-resistant S. pneumoniae (DRSP), or—less commonly—the diagnosis may not be bacterial sinusitis at all. 1, 2, 5
• Approximately 30–40% of H. influenzae strains and 90–100% of M. catarrhalis strains produce β-lactamase, which can overwhelm the clavulanate component in standard-dose Augmentin. 3, 5

Specific Fluoroquinolone Recommendations

• Levofloxacin 500 mg once daily for 10–14 days achieves 90–92% predicted clinical efficacy with excellent coverage of multidrug-resistant S. pneumoniae (including penicillin-resistant strains), β-lactamase-producing H. influenzae, and M. catarrhalis. 2, 6, 3, 7
• Moxifloxacin 400 mg once daily for 10 days demonstrates 99% activity against S. pneumoniae and 95–100% activity against H. influenzae, making it equally effective as levofloxacin. 2, 3
• Both agents have once-daily dosing, which improves compliance compared to twice-daily regimens, and both are FDA-approved for acute bacterial sinusitis. 2, 6, 3

Alternative Second-Line Options (If Fluoroquinolones Contraindicated)

• High-dose amoxicillin-clavulanate (2 g amoxicillin/125 mg clavulanate twice daily) for 10 days provides enhanced coverage against DRSP and β-lactamase producers, though recent evidence shows no significant benefit over standard dosing in clinical outcomes. 1, 2, 8
• Third-generation cephalosporins such as cefpodoxime proxetil or cefdinir for 10 days offer superior activity against H. influenzae compared to second-generation agents, though they have limitations against DRSP. 1, 2, 5
• Cefuroxime axetil 250–500 mg twice daily has comparable efficacy to Augmentin with good activity against S. pneumoniae and adequate H. influenzae coverage. 2

Essential Adjunctive Therapies (Add to All Patients)

• Intranasal corticosteroids (mometasone, fluticasone, or budesonide) twice daily significantly reduce mucosal inflammation and accelerate symptom resolution; this is supported by strong evidence from multiple randomized controlled trials and should be added regardless of antibiotic choice. 1, 4, 2
• High-volume saline nasal irrigation 2–3 times daily improves sinus drainage, clears purulent secretions, and enhances mucociliary clearance. 1, 4, 2
• Analgesics (acetaminophen or ibuprofen) for pain and fever control provide symptomatic relief while antibiotics take effect. 1, 4

Reassessment Timeline and Escalation Protocol

• Reassess at 3–5 days after switching antibiotics: If symptoms worsen within 48–72 hours or fail to improve by day 5, further diagnostic work-up (including possible sinus aspiration cultures or imaging) is warranted. 1, 4, 2
• Reassess at 7 days: Persistent or worsening symptoms should prompt confirmation of the diagnosis, exclusion of complications (orbital cellulitis, meningitis, intracranial abscess), and consideration of CT imaging or ENT referral. 1, 4, 2
• Expected timeline: Most patients on appropriate second-line therapy should experience noticeable improvement within 3–5 days, with complete resolution by 10–14 days or when symptom-free for 7 consecutive days. 1, 4, 2

When to Refer to Otolaryngology Urgently

• No improvement after 7 days of appropriate second-line fluoroquinolone therapy indicates refractory disease requiring specialist evaluation. 1, 4, 2
• Any worsening symptoms at any point during treatment (increasing facial pain, fever, purulent drainage, severe headache, visual changes, periorbital swelling, altered mental status) mandates urgent ENT referral to exclude complications. 1, 4, 9, 2
• Recurrent sinusitis (≥3 episodes per year) requires comprehensive evaluation for underlying allergic rhinitis, immunodeficiency, or anatomic abnormalities. 1, 4

Critical Pitfalls to Avoid

• Do not extend the initial Augmentin course beyond 5–7 days without clinical improvement; this delays effective treatment and allows bacterial proliferation without benefit. 1, 4, 2
• Do not use azithromycin or other macrolides as second-line therapy; resistance rates exceed 20–25% for both S. pneumoniae and H. influenzae, making them unsuitable for sinusitis treatment. 1, 4, 3, 10
• Ensure a minimum 10-day course of the new fluoroquinolone to prevent relapse; shorter courses have been associated with higher recurrence rates in treatment failures. 1, 4, 2
• Gastrointestinal adverse effects are common with Augmentin (diarrhea in 40–43% of patients, severe diarrhea in 7–8%), but fluoroquinolones have significantly lower GI side-effect rates (7.4% vs 21.2% for levofloxacin vs Augmentin). 1, 7, 8

Confirm the Diagnosis Before Escalating Further

• If the patient fails both first-line and second-line antibiotics, reconsider whether this is truly bacterial sinusitis; 98–99.5% of acute rhinosinusitis is viral and resolves spontaneously within 7–10 days. 1, 4
• Alternative diagnoses to consider include chronic rhinosinusitis (symptoms >8 weeks), fungal sinusitis (especially in diabetics or immunocompromised patients), allergic fungal sinusitis, anatomic obstruction, or non-infectious inflammatory conditions. 1, 9
• CT imaging should be reserved for suspected complications or when the diagnosis remains uncertain after appropriate antibiotic trials; routine imaging is not recommended for uncomplicated cases. 1, 4