How should I manage an acute bacterial exacerbation of chronic sinusitis, including first‑line antibiotics, intranasal corticosteroids, and adjunctive therapies?

Management of Acute Bacterial Exacerbation of Chronic Sinusitis

First-Line Antibiotic Selection

For acute bacterial exacerbations of chronic sinusitis, prescribe amoxicillin-clavulanate 875 mg/125 mg twice daily for 10–14 days (or until symptom-free for 7 consecutive days), as this regimen provides 90–92% predicted efficacy against the polymicrobial flora typical of chronic disease. 1

• Chronic sinusitis harbors a different microbial profile than acute disease: anaerobic bacteria (Fusobacterium spp., Prevotella spp.) and Staphylococcus aureus predominate alongside the typical acute pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis). 2, 3

• The clavulanate component is essential because 30–40% of H. influenzae, 90–100% of M. catarrhalis, and many anaerobes produce β-lactamase, rendering plain amoxicillin ineffective. 1, 2

• Treatment duration for chronic sinusitis exacerbations must be longer than for acute disease: a minimum 3-week course is recommended when infectious etiology is confirmed, though many experts initiate therapy with 10–14 days and extend if response is incomplete. 4

Alternative Regimens for Penicillin Allergy

• Non-severe (non-type I) penicillin allergy: Use a second- or third-generation cephalosporin (cefuroxime-axetil, cefpodoxime-proxetil, cefdinir, or cefprozil) for 10–14 days; cross-reactivity is negligible. 1

• Severe (type I/anaphylactic) penicillin allergy: Prescribe 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 pathogens. 1

• For patients requiring anaerobic coverage who cannot take amoxicillin-clavulanate: Combine clindamycin (which covers anaerobes and S. aureus) with metronidazole or use clindamycin plus a third-generation cephalosporin to ensure complete pathogen coverage. 2

Essential Adjunctive Therapies (Add to All Patients)

Intranasal corticosteroids and saline nasal irrigation are the cornerstone of chronic sinusitis management and must be continued during acute exacerbations. 4

• Intranasal corticosteroids (mometasone, fluticasone, or budesonide) administered twice daily reduce mucosal inflammation, improve sinus drainage, and enhance antibiotic penetration; supported by strong evidence from multiple randomized controlled trials. 1, 4, 5, 6

• High-volume saline nasal irrigation performed 2–3 times daily mechanically clears purulent secretions, reduces bacterial load, and improves medication delivery to the sinonasal mucosa. 1, 4, 5

• Analgesics (acetaminophen or ibuprofen) for pain and fever control. 1

• Short-term oral corticosteroids (e.g., prednisone 30–60 mg daily for 5–7 days) may be added for patients with marked mucosal edema, nasal polyps, or severe symptoms unresponsive to intranasal steroids alone; this is particularly beneficial in chronic non-infectious sinusitis with polyposis. 4, 5

Monitoring, Reassessment, and Treatment Failure Protocol

• Reassess at 3–5 days: If no clinical improvement (persistent purulent drainage, unchanged facial pain, or worsening), switch to a respiratory fluoroquinolone (levofloxacin or moxifloxacin) or consider combination therapy with clindamycin plus a cephalosporin for enhanced anaerobic coverage. 1, 4

• Reassess at 7–10 days: Persistent symptoms warrant confirmation of diagnosis with CT imaging (if not already obtained) and consideration of endoscopic sinus culture to guide targeted antibiotic therapy, as nasopharyngeal swabs are unreliable in chronic disease. 1, 4

• By 3 weeks: If symptoms persist despite appropriate antibiotics and adjunctive therapies, refer to otolaryngology for endoscopic evaluation and consideration of functional endoscopic sinus surgery (FESS). 4, 5

When to Obtain Imaging and Cultures

• CT scanning is indicated when chronic sinusitis is refractory to medical therapy, to define anatomic abnormalities (ostiomeatal complex obstruction, concha bullosa, septal deviation) and guide surgical planning. 4, 5

• Direct sinus aspiration or endoscopic middle-meatus culture should be obtained in patients who fail empiric therapy, have recurrent exacerbations (≥3 per year), or are immunocompromised, as culture-directed therapy significantly improves outcomes in chronic disease. 1, 4

Antibiotics to Avoid in Chronic Sinusitis Exacerbations

• Macrolides (azithromycin, clarithromycin) have 20–25% resistance rates among respiratory pathogens and lack anaerobic coverage, making them unsuitable for chronic sinusitis exacerbations. 1, 7

• Trimethoprim-sulfamethoxazole shows ≈50% resistance in S. pneumoniae and ≈27% in H. influenzae, and provides no anaerobic coverage. 1, 5

• First-generation cephalosporins (cephalexin) are inadequate because they lack activity against H. influenzae and anaerobes. 1

Addressing Underlying Contributing Factors

Chronic sinusitis is multifactorial; successful management requires identifying and treating predisposing conditions. 4, 5

• Allergic rhinitis: Obtain allergen testing and add daily non-sedating antihistamines (cetirizine, loratadine, or fexofenadine) plus allergen avoidance measures. 4, 5

• Immunodeficiency: Measure serum immunoglobulins (IgG, IgA, IgM) and functional antibody responses (pneumococcal titers) in patients with recurrent infections; consider immunoglobulin replacement if deficient. 4

• Gastroesophageal reflux disease (GERD): Treat with proton pump inhibitors (omeprazole 20–40 mg daily) as laryngopharyngeal reflux can perpetuate chronic sinonasal inflammation. 4

• Aspirin sensitivity/Samter's triad: Patients with nasal polyps, asthma, and aspirin sensitivity require aggressive medical management with high-dose intranasal corticosteroids, leukotriene modifiers (montelukast), and often systemic corticosteroids; aspirin desensitization may be considered. 4

Indications for Surgical Referral

Refer to otolaryngology for functional endoscopic sinus surgery (FESS) when any of the following are present: 4, 5

• Documented chronic sinus infection refractory to ≥3 weeks of appropriate antibiotic therapy plus maximal medical management (intranasal corticosteroids, saline irrigation, treatment of underlying conditions).

• Anatomic obstruction amenable to surgical correction (ostiomeatal complex blockage, concha bullosa, severe septal deviation).

• Nasal polyps that fail to respond to medical therapy including systemic corticosteroids.

• Recurrent acute exacerbations (≥3–4 per year) despite optimal medical management.

• Suspected complications (orbital cellulitis, meningitis, intracranial abscess).

Critical Pitfalls to Avoid

• Do not treat chronic sinusitis exacerbations with the same short courses used for acute disease; inadequate duration (5–7 days) leads to relapse and promotes resistance. 4

• Never prescribe antibiotics without concurrent intranasal corticosteroids and saline irrigation in chronic sinusitis; antibiotics alone have limited efficacy without addressing the underlying mucosal inflammation. 4, 5, 6

• Avoid prolonged use of topical decongestants (oxymetazoline) beyond 3 days, as rebound congestion (rhinitis medicamentosa) worsens the underlying condition. 5

• Do not assume all purulent drainage indicates bacterial infection; chronic sinusitis often involves persistent inflammation with sterile purulence, and antibiotics may not be needed for every exacerbation if symptoms are mild and improving. 4, 6

• Ensure adequate treatment of underlying allergic rhinitis; uncontrolled allergy perpetuates the inflammatory cycle and leads to treatment failure regardless of antibiotic choice. 4, 5