What oral (PO) antibiotics cover Pseudomonas aeruginosa?

Oral Antibiotics for Pseudomonas Aeruginosa Coverage

For oral treatment of Pseudomonas aeruginosa infections, ciprofloxacin (750 mg twice daily) and levofloxacin (750 mg daily) are the only reliable oral antibiotic options available.

First-Line Oral Options

Ciprofloxacin

• Dosing: 750 mg PO twice daily 1, 2
• Evidence strength: Strong recommendation based on clinical guidelines
• Advantages:
  • Most extensively studied oral option for Pseudomonas
  • Higher serum and bronchial concentrations achieved with 750 mg dosing
  • First-line choice when oral route is available in patients with risk factors for P. aeruginosa 1

Levofloxacin

• Dosing: 750 mg PO daily 1, 2, 3
• Evidence strength: FDA-approved but with less extensive clinical experience
• Considerations:
  • Alternative to ciprofloxacin when oral treatment is needed
  • Requires high-dose (750 mg) to achieve adequate coverage 1
  • Some studies suggest comparable activity to ciprofloxacin against P. aeruginosa 4, 5

Clinical Decision Algorithm

1. Assess infection severity:

   • For mild-moderate infections: Oral therapy may be appropriate
   • For severe infections: Start with IV therapy, then consider oral step-down

2. Risk stratification for P. aeruginosa:

   • Consider P. aeruginosa if patient has ≥2 of:
     • Recent hospitalization
     • Frequent/recent antibiotics (>4 courses/year or within last 3 months)
     • Severe underlying disease (FEV1 <30%)
     • Oral steroid use (>10 mg prednisolone daily in last 2 weeks) 1

3. Antibiotic selection:

   • First choice: Ciprofloxacin 750 mg PO twice daily
   • Alternative: Levofloxacin 750 mg PO daily

Important Considerations

• Resistance concerns: Rapid emergence of resistance is a significant concern with fluoroquinolone monotherapy against Pseudomonas 2
• Culture guidance: Always obtain cultures before starting therapy when possible 1
• Combination therapy: Consider combination therapy for severe infections, particularly in immunocompromised patients 2
• Duration: Generally 7-10 days for respiratory infections; longer for other sites 2
• Monitoring: Follow clinical response and consider repeat cultures if inadequate improvement 1

Pitfalls to Avoid

1. Underdosing: Using standard doses of fluoroquinolones (e.g., ciprofloxacin 500 mg or levofloxacin 500 mg) provides inadequate coverage for Pseudomonas
2. Monotherapy in severe infections: Consider combination therapy for severe infections, especially in immunocompromised hosts
3. Ignoring local resistance patterns: Local antibiograms should guide therapy when available
4. Failure to obtain cultures: Always try to obtain cultures before starting therapy to guide definitive treatment
5. Overlooking non-infectious causes of symptoms: Consider non-infectious causes if patient fails to respond to appropriate therapy

Remember that there are NO oral beta-lactams, aminoglycosides, or other antibiotic classes that reliably cover Pseudomonas aeruginosa. When oral therapy is required, high-dose fluoroquinolones (ciprofloxacin or levofloxacin) are the only options.