Antibiotics for Pseudomonas in Sinus Infections
For Pseudomonas aeruginosa sinusitis, use ciprofloxacin 750 mg orally twice daily for 14 days as first-line oral therapy, or an intravenous antipseudomonal β-lactam (ceftazidime, cefepime, piperacillin-tazobactam, or meropenem) for severe infections. 1, 2
First-Line Oral Therapy
- Ciprofloxacin 750 mg PO twice daily for 14 days is the only reliable oral antibiotic with consistent Pseudomonas coverage for sinus infections 1, 2
- This high-dose regimen (not 500 mg) is essential because lower doses fail to achieve adequate sinus tissue concentrations 1
- Levofloxacin 750 mg PO daily is a second-line alternative, though it is less potent against Pseudomonas than ciprofloxacin 1, 3
Intravenous Options for Severe Infections
When patients are severely ill, immunocompromised, or have failed oral therapy, use IV antipseudomonal agents:
- Ceftazidime 2g IV every 8 hours 1
- Cefepime 2g IV every 8 hours 1
- Piperacillin-tazobactam 4.5g IV every 6 hours (use extended 4-hour infusion for critically ill patients) 1
- Meropenem 1g IV every 8 hours 1
When to Use Combination Therapy
Add a second antipseudomonal agent from a different class in these scenarios:
- Critically ill or septic patients 1
- Immunocompromised hosts 4
- Prior fluoroquinolone use within 90 days (increases resistance risk) 2, 5
- Documented multidrug-resistant Pseudomonas 1
Combination regimens: Antipseudomonal β-lactam PLUS either ciprofloxacin 400mg IV every 8 hours OR tobramycin 5-7 mg/kg IV daily 1
Critical Pitfalls to Avoid
- Never use standard sinusitis antibiotics like amoxicillin-clavulanate, ceftriaxone, cefuroxime, or macrolides—these have zero activity against Pseudomonas 6, 1, 4
- Do not underdose ciprofloxacin—500 mg twice daily is insufficient; you must use 750 mg twice daily 1
- Avoid empiric fluoroquinolones without culture confirmation, as 13-20% of sinus Pseudomonas isolates are already fluoroquinolone-resistant, especially in post-surgical patients 5
- Obtain sinus cultures before starting antibiotics to guide therapy, particularly in patients with prior sinus surgery where Pseudomonas is cultured in nearly 20% of cases 4, 5
Special Populations
Post-surgical chronic rhinosinusitis patients:
- Pseudomonas is isolated in nearly 1 in 5 patients with previous endoscopic sinus surgery 5
- Mucoid strains are significantly more likely to be fluoroquinolone-resistant 5
- Always obtain culture-directed therapy rather than empiric treatment 5
Immunocompromised patients:
- Pseudomonas has emerged as a major pathogen in immunocompromised hosts and those with nasal tubes or catheters 4
- Combination IV therapy is strongly recommended over monotherapy 1, 4
Treatment Duration and Monitoring
- Standard duration: 14 days for documented Pseudomonas sinus infections 1, 2
- If no clinical improvement by day 3-5 on oral therapy, switch to IV combination therapy 1
- Monitor for resistance development, particularly with monotherapy 1, 5