Cefepime Susceptibility Testing 

Cefepime is a fourth-generation cephalosporin with broad-spectrum activity against Gram-positive and Gram-negative bacteria, including organisms producing AmpC beta-lactamases. It is widely used to treat serious bacterial infections, such as pneumonia, urinary tract infections, intra-abdominal infections, and sepsis. Susceptibility testing for cefepime is crucial to determine its efficacy, particularly in the context of rising resistance due to extended-spectrum beta-lactamases (ESBLs) and carbapenemases.

Content:

• Testing Methods:
  • Disk Diffusion (Kirby-Bauer Method):
    • Disks containing cefepime (30 µg) are placed on agar plates inoculated with the bacterial isolate.
    • After incubation, the diameter of the inhibition zone is measured and interpreted using CLSI or EUCAST breakpoints.
  • Minimum Inhibitory Concentration (MIC) Testing:
    • MIC testing is performed using broth microdilution, agar dilution, or automated systems.
    • The MIC is the lowest concentration of cefepime that inhibits visible bacterial growth.
• • Automated Testing Systems:
    • Platforms like Vitek, Phoenix, or MicroScan can rapidly determine cefepime MICs.

Application:

• Clinical Use:
  • Cefepime is used for:
    • Healthcare-associated pneumonia and ventilator-associated pneumonia.
    • Complicated urinary tract infections and pyelonephritis.
    • Intra-abdominal infections (often combined with metronidazole for anaerobic coverage).
    • Febrile neutropenia as an empirical therapy.
    • Bacteremia and sepsis caused by susceptible pathogens.
  • Susceptibility testing ensures its efficacy in serious infections caused by multidrug-resistant (MDR) organisms.
• Antimicrobial Stewardship:
  • Promotes the appropriate use of cefepime in treating infections caused by susceptible organisms.
  • Encourages switching to narrower-spectrum antibiotics when possible to prevent resistance.

Cefepime susceptibility testing is vital for determining its activity against Gram-positive and Gram-negative bacteria, especially in the context of multidrug resistance. Standardized methods, such as disk diffusion and MIC testing, ensure reliable results.