Cefiderocol Susceptibility Testing
Cefiderocol is a novel siderophore cephalosporin antibiotic designed to treat infections caused by multidrug-resistant Gram-negative bacteria, including carbapenem-resistant organisms. Cefiderocol enters bacterial cells by utilizing the siderophore iron transport system, allowing it to overcome resistance mechanisms such as porin loss. It is active against organisms producing extended-spectrum beta-lactamases (ESBLs), AmpC beta-lactamases, and even some metallo-beta-lactamases (MBLs). Susceptibility testing for cefiderocol is critical for ensuring appropriate use and monitoring emerging resistance.
Content:
- Testing Methods:
- Broth Microdilution (BMD):
- CLSI and EUCAST recommend broth microdilution as the gold standard for determining cefiderocol MICs.
- Iron-depleted cation-adjusted Mueller-Hinton Broth (ID-CAMHB) must be used to simulate physiological conditions for optimal testing.
- Broth Microdilution (BMD):
- E-test (Gradient Diffusion):
- Not recommended for cefiderocol due to inconsistent results and lack of standardization.
- Automated Testing Systems:
- Automated systems like Vitek or Phoenix may incorporate cefiderocol in their panels; however, validation and calibration for cefiderocol are still ongoing in many systems.
- E-test (Gradient Diffusion):
Application:
- Clinical Use:
- Cefiderocol is approved for treating:
- Complicated urinary tract infections (cUTIs).
- Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP).
- Bloodstream infections (BSIs) caused by multidrug-resistant Gram-negative bacteria.
- Carbapenem-resistant infections due to Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterobacterales.
- Cefiderocol is approved for treating:
- Antimicrobial Stewardship:
- Helps guide targeted therapy for multidrug-resistant infections, avoiding unnecessary use of last-line antibiotics.
- Epidemiological Surveillance:
- Monitors the emergence of resistance among carbapenemase-producing organisms and other multidrug-resistant pathogens.
Cefiderocol susceptibility testing is essential for managing infections caused by multidrug-resistant Gram-negative pathogens, including carbapenem-resistant Enterobacterales and Pseudomonas aeruginosa.
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