Tigecycline Effectiveness Against Enterococcus Bacteria
Yes, tigecycline is effective against Enterococcus bacteria, including vancomycin-resistant Enterococcus (VRE), but its use should be limited to specific infection sites such as intra-abdominal infections and complicated skin and skin structure infections. 1, 2
Spectrum of Activity and FDA Approval
- Tigecycline is a glycylcycline antibiotic with documented activity against Enterococcus faecalis (vancomycin-susceptible isolates) as stated in its FDA-approved indications for complicated skin and skin structure infections and complicated intra-abdominal infections 2
- Tigecycline demonstrates broad-spectrum activity against difficult-to-treat pathogens including vancomycin-resistant Enterococcus species 3
- It maintains activity against Enterococcus regardless of their susceptibility to other tetracyclines, making it valuable for multidrug-resistant strains 4
Clinical Applications for Enterococcal Infections
- Tigecycline is specifically recommended as the drug of choice for intra-abdominal infections caused by VRE with a loading dose of 100 mg IV followed by 50 mg IV every 12 hours 1
- For polymicrobial infections involving VRE, tigecycline is considered appropriate treatment according to clinical guidelines 1
- A retrospective study evaluating 132 patients with various infections (including 42 with VRE) found an overall success rate of 97.6% with tigecycline treatment 1
Important Limitations and Considerations
- Tigecycline should not be used for VRE bacteremia due to its large volume of distribution and resulting low serum levels 1
- For bloodstream infections with VRE, high-dose daptomycin (8-12 mg/kg IV daily) alone or in combination with β-lactams is recommended instead 1
- For urinary tract infections caused by VRE, other agents like fosfomycin, nitrofurantoin, or high-dose ampicillin are preferred over tigecycline 1
Dosing Considerations
- Standard dosing for tigecycline is a 100 mg IV loading dose followed by 50 mg IV every 12 hours 2
- For severe infections with higher MICs, some research suggests that higher maintenance doses (up to 200 mg/day) may be needed for optimal efficacy against VRE, particularly for complicated skin and soft tissue infections 5
- The duration of treatment with tigecycline should be guided by the site of infection and clinical response, typically ranging from 5-14 days 1, 2
Resistance Mechanisms
- Although rare compared to resistance in Gram-negative bacteria, reduced susceptibility to tigecycline in Enterococcus faecium has been documented through mutations in the rpsJ gene (coding for the S10 protein of the 30S ribosomal subunit) 6
- Unlike tetracyclines, tigecycline overcomes many common tetracycline resistance mechanisms, explaining its retained activity against tetracycline-resistant enterococci 7
Combination Therapy
- Tigecycline has been successfully used in combination with other antimicrobials for VRE infections 1
- The combination of tigecycline and gentamicin may provide improved activity against VRE strains in some cases 4
Remember that while tigecycline is effective against Enterococcus, its use should be targeted to appropriate infection sites (primarily intra-abdominal infections and skin/soft tissue infections) and avoided in bacteremia due to its pharmacokinetic limitations.