Treatment of Moraxella Infections
Amoxicillin-clavulanate is the recommended first-line treatment for Moraxella infections due to widespread beta-lactamase production in these organisms. 1, 2
Microbiology and Clinical Significance
- Moraxella catarrhalis (formerly Branhamella catarrhalis) is a gram-negative coccus that commonly causes respiratory tract infections 3
- Most strains (>90%) produce beta-lactamase, making them resistant to penicillin, ampicillin, and amoxicillin 2
- Moraxella is a common pathogen in acute otitis media in children (15-20% of cases) and acute exacerbations of COPD in adults 3
First-Line Treatment Options
- Amoxicillin-clavulanate (875/125 mg twice daily for adults) is the preferred agent for Moraxella infections due to its effectiveness against beta-lactamase-producing strains 1, 4
- For respiratory infections involving Moraxella catarrhalis, a 5-day course is typically sufficient for uncomplicated cases 4
- In children, amoxicillin-clavulanate dosed at 25 mg/kg/day of the amoxicillin component in 2 divided doses is recommended 4
Alternative Treatment Options
- Respiratory fluoroquinolones (levofloxacin 750 mg daily) are effective against Moraxella and can be used in patients with penicillin allergy 5, 4
- Doxycycline (100 mg twice daily) provides good coverage for Moraxella infections and is a suitable alternative 4
- Cephalosporins such as cefuroxime-axetil, cefpodoxime-proxetil, or cefixime are effective against beta-lactamase-producing Moraxella 4
- Azithromycin (500 mg on day 1, then 250 mg for 4 days) can be used, particularly in cases of cat scratch disease where Moraxella may be a consideration 4, 6
Treatment Based on Infection Site
Respiratory Tract Infections
- For acute exacerbations of COPD involving Moraxella, limit antibiotic treatment duration to 5 days 4
- For community-acquired pneumonia with Moraxella, levofloxacin (750 mg daily) or amoxicillin-clavulanate are effective options 5, 4
- In sinusitis caused by Moraxella, amoxicillin-clavulanate is recommended for patients with persistent symptoms for more than 10 days 4
Otitis Media
- For acute otitis media caused by Moraxella in children, amoxicillin-clavulanate is the preferred agent 4, 6
- Treatment duration is 8-10 days for children under 2 years and 5 days for older children 4
Skin and Soft Tissue Infections
- For skin and soft tissue infections involving Moraxella, amoxicillin-clavulanate is effective 1, 4
- For more severe infections, parenteral therapy may be necessary 4
Special Considerations
- Immunocompromised patients: Moraxella can cause bacteremic pneumonia in immunosuppressed patients, requiring prompt and aggressive treatment 7
- Ocular infections: Moraxella species rarely cause keratitis but can superinfect existing corneal lesions; fluoroquinolones like ciprofloxacin are effective 8
- Nosocomial infections: Increasing documentation of nosocomial transmission requires attention to infection control measures 2
Common Pitfalls to Avoid
- Misidentification: Moraxella resembles commensal Neisseria species in culture and may be overlooked in respiratory samples 3
- Inappropriate antibiotic selection: Using penicillin, ampicillin, or amoxicillin alone is ineffective due to beta-lactamase production 2
- Inadequate duration: While short courses (5 days) are typically sufficient for uncomplicated infections, more severe cases may require longer treatment 4
- Failure to recognize resistance: Always consider local resistance patterns when selecting empiric therapy 4
By following these evidence-based recommendations, clinicians can effectively manage Moraxella infections while practicing antimicrobial stewardship.