What infections are not covered by tigecycline, particularly in cases of bacteremia caused by vancomycin-resistant Enterococcus (VRE)?

Tigecycline Should Not Be Used for VRE Bacteremia Due to Poor Plasma Concentrations

Tigecycline should not be used for treating bacteremia caused by vancomycin-resistant Enterococcus (VRE) due to its large volume of distribution and resulting low serum levels. 1, 2

Infections Not Covered by Tigecycline

Bloodstream Infections

• Tigecycline performs poorly in bacteremic patients due to poor plasma concentrations, with a much higher risk of failing to clear bacteremia 1
• For VRE bacteremia specifically, tigecycline is contraindicated due to its large volume of distribution and low serum levels 1, 2
• High-dose daptomycin (8-12 mg/kg/day) alone or in combination with β-lactams is recommended instead for VRE bacteremia 1, 2
• Linezolid is another preferred option for VRE bloodstream infections with clinical cure rates of 81.4% 1, 3

Healthcare-Associated Pneumonia

• Tigecycline should not be considered as first-line therapy in patients with healthcare-associated pneumonia 1
• The drug's pharmacokinetic properties result in suboptimal concentrations in lung tissue for treating pneumonia effectively 1

Appropriate Uses of Tigecycline for VRE

Despite its limitations for bacteremia, tigecycline is effective for certain VRE infections:

• Tigecycline is recommended as the drug of choice for intra-abdominal infections caused by VRE 1, 2
• For polymicrobial infections involving VRE, tigecycline is appropriate treatment with a loading dose of 100 mg IV followed by 50 mg IV every 12 hours 1, 2
• A retrospective study reported an overall success rate of 97.6% when using tigecycline for various VRE infections, particularly intra-abdominal infections 1

Alternative Treatments for VRE Infections

When tigecycline is not appropriate, these alternatives should be considered:

• Linezolid 600 mg IV or PO every 12 hours is strongly recommended for VRE infections, including bacteremia 1
• High-dose daptomycin (8-12 mg/kg/day) alone or in combination with β-lactams is recommended for VRE bacteremia 1
• For uncomplicated urinary tract infections due to VRE, options include fosfomycin 3g PO single dose, nitrofurantoin 100 mg PO every 6 hours, or high-dose ampicillin (18-30g IV daily in divided doses) 1

Clinical Implications and Outcomes

• Inappropriate antibiotic therapy for VRE bacteremia significantly impacts mortality rates 4
• The 30-day mortality rate for patients with VRE bacteremia treated with inappropriate antibiotics was 54% compared to 26% for those treated with appropriate antibiotics 4
• Median survival for patients treated with inappropriate antibiotics was only 1 month compared to 11 months for those receiving appropriate antibiotics 4
• Using tigecycline for VRE bacteremia would be considered inappropriate therapy due to its pharmacokinetic limitations 1, 2

Susceptibility Testing Considerations

• When evaluating treatment options for VRE, reliable susceptibility testing is essential 5
• Broth microdilution is the gold standard for determining susceptibility to linezolid, daptomycin, and tigecycline against VRE 5
• Agreement between broth microdilution and Etest for tigecycline susceptibility testing has been reported as suboptimal 5