Tigecycline is Not Effective Against Pseudomonas aeruginosa
Tigecycline should not be used for Pseudomonas aeruginosa infections as it has inadequate activity against this organism. 1
Antimicrobial Activity Against Pseudomonas
- Tigecycline demonstrates poor activity against Pseudomonas aeruginosa, with studies showing high MIC values (minimum inhibitory concentrations) ranging from 4-64 mg/L 2
- P. aeruginosa shows decreased susceptibility to tigecycline with MIC90 values of 16 μg/mL, making it clinically ineffective 3
- The European Society of Clinical Microbiology and Infectious Diseases (ESCMID) guidelines do not recommend tigecycline for Pseudomonas infections due to its inadequate activity 4
Mechanism of Resistance
- Pseudomonas aeruginosa bears efflux pump systems such as MexXY-OprM that actively remove tigecycline from bacterial cells, contributing to intrinsic resistance 5
- Almost 90% of P. aeruginosa strains tested in studies show resistance to tigecycline 5
Clinical Implications
- For carbapenem-resistant Pseudomonas aeruginosa (CRPA) infections, ESCMID guidelines suggest therapy with ceftolozane-tazobactam if active in vitro, rather than tigecycline 4
- For non-severe CRPA infections, old antibiotics should be chosen from among in vitro active agents according to the source of infection 4
- The FDA has issued a Boxed Warning for tigecycline, recommending consultation with infectious disease specialists when considering its use 4
Potential Exceptions and Combination Therapy
- In extremely limited circumstances, tigecycline might be considered as part of combination therapy for multi-drug resistant P. aeruginosa when conventional antibiotics have failed 6
- One case report described successful use of tigecycline in combination with other antibiotics (meropenem, amikacin, and colistin) for multi-drug-resistant P. aeruginosa sepsis in a critically ill infant, but this is not standard practice 6
- Some in vitro studies suggest synergy between tigecycline and antimicrobial peptides like pexiganan against P. aeruginosa, but this has not translated to clinical practice recommendations 2
Alternative Treatment Options for Pseudomonas Infections
- For carbapenem-resistant Pseudomonas aeruginosa (CRPA), ESCMID guidelines recommend:
- Antipseudomonal drugs that may be effective include carbapenems, cephalosporins (ceftazidime, cefepime), fluoroquinolones, aminoglycosides, and polymyxins, depending on susceptibility patterns 4
Conclusion
Tigecycline should not be considered for Pseudomonas aeruginosa infections due to its inadequate activity against this pathogen. Treatment should be guided by antimicrobial susceptibility testing and current guidelines, which recommend other agents with proven efficacy against Pseudomonas.