Is mupirocin effective for treating pseudomonas infections?

Mupirocin is Not Effective for Treating Pseudomonas Infections

Mupirocin is not recommended for treating Pseudomonas aeruginosa infections as it lacks significant activity against this organism. Despite being ironically produced by Pseudomonas fluorescens, mupirocin's spectrum of activity does not effectively cover Pseudomonas aeruginosa or most other gram-negative bacilli.

Spectrum of Activity of Mupirocin

Mupirocin has a specific antimicrobial spectrum that includes:

• Highly active against:

  • Staphylococci (including MRSA)
  • Streptococci

• Limited activity against:

  • Select gram-negative bacteria (Haemophilus influenzae, Neisseria gonorrhoeae)
  • Much less active against most gram-negative bacilli including Pseudomonas aeruginosa 1

Recommended Agents for Pseudomonas Infections

For Pseudomonas aeruginosa infections, particularly carbapenem-resistant strains, guidelines recommend:

1. For susceptible Pseudomonas aeruginosa:

   • Piperacillin or piperacillin/tazobactam
   • Ceftazidime, cefepime, or cefpirome
   • Ciprofloxacin or levofloxacin
   • Amikacin (for urinary tract infections only) 2

2. For difficult-to-treat Pseudomonas aeruginosa:

   • Colistin (monotherapy or combination)
   • Ceftolozane/tazobactam
   • Ceftazidime/avibactam
   • Imipenem/cilastatin/relebactam 2

Clinical Applications of Mupirocin

Mupirocin is appropriately used for:

1. Topical treatment of skin infections:

   • Primary skin infections like impetigo
   • Secondary infected skin lesions (eczema, ulcers, lacerations) 2

2. MRSA decolonization:

   • Nasal decolonization with mupirocin 2% ointment applied twice daily for 5-10 days
   • Often combined with chlorhexidine washes or dilute bleach baths for body decolonization 3

Pharmacological Properties Limiting Use Against Pseudomonas

Several properties of mupirocin make it unsuitable for Pseudomonas infections:

• Rapid systemic metabolism limits its use to topical applications only 4
• High protein binding (95%) in human serum significantly reduces activity 1
• Slow bactericidal action against even susceptible organisms 1
• Activity primarily against gram-positive organisms with limited gram-negative coverage 5

Appropriate Alternatives for Pseudomonas Infections

For respiratory Pseudomonas infections in cystic fibrosis patients, guidelines recommend:

• Colistin (often via inhalation)
• Tobramycin
• Combination therapies with beta-lactams and aminoglycosides 2

Conclusion

While mupirocin is valuable for treating staphylococcal and streptococcal skin infections and for MRSA decolonization, it should not be considered for Pseudomonas aeruginosa infections. Appropriate antimicrobial selection based on susceptibility testing is essential for effective treatment of Pseudomonas infections.