Tigecycline Coverage Against MRSA
Yes, tigecycline has documented in vitro activity against MRSA and is FDA-approved for treating complicated skin and skin structure infections caused by methicillin-resistant Staphylococcus aureus, but it should NOT be your first-line choice due to inferior efficacy compared to vancomycin or linezolid. 1
FDA-Approved Indications for MRSA
- Tigecycline is specifically indicated for complicated skin and skin structure infections caused by MRSA (both methicillin-susceptible and -resistant S. aureus isolates) in patients 18 years and older 1
- Tigecycline is also indicated for complicated intra-abdominal infections caused by MRSA 1
Critical Limitations for MRSA Treatment
Tigecycline should NEVER be used for MRSA bacteremia or bloodstream infections due to extremely low serum concentrations that make treatment of bacteremic infections essentially impossible 2, 3
- For suspected or confirmed MRSA pneumonia, guidelines recommend vancomycin or linezolid as preferred agents, not tigecycline 4
- Tigecycline is specifically NOT indicated for diabetic foot infections—it failed to meet non-inferiority criteria compared to ertapenem and was associated with significantly more drug discontinuations 2, 1
Comparative Efficacy Data
- In a Phase 3 trial comparing tigecycline to vancomycin for MRSA infections, clinical cure rates in the microbiologically evaluable population were 81.4% (tigecycline) versus 83.9% (vancomycin), showing tigecycline was non-inferior but not superior 5
- For MRSA complicated skin and skin structure infections specifically, cure rates were similar: 86.4% with tigecycline versus 86.9% with vancomycin 5
- However, nausea or vomiting occurred more frequently with tigecycline (41.0%) than vancomycin (17.9%), though most cases were mild 5
In Vitro Activity Profile
- Tigecycline demonstrates MIC values of ≤0.5 mg/L against MRSA isolates, with susceptibility rates of approximately 85.5% 6
- In vitro studies show tigecycline inhibits protein translation by binding to the 30S ribosomal subunit and is not affected by tetracycline resistance mechanisms, beta-lactamases, or methicillin resistance 1
- Tigecycline exhibits activity against both hospital-associated and community-associated MRSA strains 7
When Tigecycline May Be Considered for MRSA
Reserve tigecycline for MRSA infections only when:
- Patient has documented resistance or intolerance to vancomycin and linezolid 3
- Infection is limited to complicated skin/soft tissue or intra-abdominal sites (NOT bloodstream or pneumonia) 1
- Consider combination therapy with rifampin for foreign-body infections, as tigecycline-rifampin prevents emergence of rifampin resistance 8
Dosing Considerations for Severe MRSA Infections
- Standard dosing: 100 mg loading dose, then 50 mg every 12 hours 1
- For severe infections in patients with normal hepatic function, higher doses (200 mg loading, then 100 mg every 12 hours) may be considered, though this is primarily studied for other pathogens 9
Common Pitfalls to Avoid
- Never use tigecycline as monotherapy for MRSA bacteremia—poor serum levels make this ineffective 2, 3
- Do not use for hospital-acquired or ventilator-associated pneumonia—greater mortality and decreased efficacy were reported in comparative trials 1
- Avoid in diabetic foot infections—clinical trial demonstrated failure to meet non-inferiority 2, 1
- Monitor for gastrointestinal adverse events (nausea, vomiting, abdominal pain) which occur more frequently than with comparators 5