Tigecycline's FDA-Approved Uses
Tigecycline, a glycylcycline antibiotic, is FDA-approved for complicated skin and skin structure infections (cSSSI), complicated intra-abdominal infections (cIAI), and community-acquired bacterial pneumonia (CABP) in patients 18 and older.[1] It targets bacteria like Staphylococcus aureus (methicillin-susceptible and some resistant strains), Streptococcus pneumoniae, Enterobacteriaceae (e.g., E. coli, Klebsiella), Bacteroides species, and anaerobes common in these infections.[1][2]
How Tigecycline Works Against Bacteria
It binds to the 30S ribosomal subunit, inhibiting protein synthesis with broad-spectrum activity against Gram-positive, Gram-negative, and anaerobic bacteria. It's particularly effective against multidrug-resistant (MDR) pathogens like methicillin-resistant S. aureus (MRSA), vancomycin-resistant enterococci (VRE), and extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, where other antibiotics fail.[2][3]
Strongest Evidence in Complicated Infections
Clinical trials show highest efficacy in:
- Complicated intra-abdominal infections: 86-92% cure rates against polymicrobial infections involving E. coli, Klebsiella, and anaerobes like Bacteroides fragilis.[1][4]
- Complicated skin infections: 80-90% success against MRSA and mixed infections.[1][4]
- Hospital-acquired/ventilator-associated pneumonia: Approved in some regions, with moderate efficacy (60-70%) against Acinetobacter baumannii and Klebsiella, though U.S. label limits it due to higher mortality risk.[1][5]
Limitations and Infections Where It's Less Effective
Tigecycline has poor lung and blood penetration, reducing effectiveness in bacteremia, urinary tract infections, and primary pneumonia.[1][3] It's not recommended for Proteus, Pseudomonas aeruginosa, or Providencia species due to intrinsic resistance.[2] FDA warnings highlight increased mortality in certain hospital pneumonias.[5]
Common Pathogens and Resistance Patterns
| Infection Type | Key Effective Pathogens | Notes |
|---------------|-------------------------|-------|
| cSSSI | MRSA, MSSA, Streptococcus pyogenes, Enterobacteriaceae | Covers 90%+ of community isolates [2] |
| cIAI | E. coli, Klebsiella pneumoniae, Bacteroides spp. | Strong vs. anaerobes [4] |
| CABP | S. pneumoniae, Haemophilus influenzae | Limited vs. atypicals [1] |
Resistance emerges via efflux pumps or ribosomal mutations, especially in Acinetobacter.[3]
[1]: FDA Label for Tygacil (tigecycline)
[2]: Clinical Microbiology Reviews - Tigecycline Activity
[3]: Antimicrobial Agents and Chemotherapy - Tigecycline Spectrum
[4]: New England Journal of Medicine - Tigecycline Trials
[5]: FDA Drug Safety Communication - Tigecycline Mortality Risk