Cefpirome Susceptibility Testing 

Cefpirome is a fourth-generation cephalosporin with broad-spectrum activity against Gram-negative and Gram-positive bacteria. It is highly effective against many Enterobacterales and some Pseudomonas aeruginosa strains due to its stability against many beta-lactamases, including AmpC beta-lactamases. Cefpirome is primarily used for severe infections, such as septicemia, lower respiratory tract infections, and neutropenic fever. Susceptibility testing is essential to guide its appropriate use, especially in settings of multidrug-resistant organisms.

Content:

• Testing Methods:
  • Disk Diffusion (Kirby-Bauer Method):
    • Disks containing cefpirome (30 µg) are placed on Mueller-Hinton agar plates inoculated with the bacterial isolate.
    • After incubation, the diameter of the inhibition zone is measured and interpreted using CLSI or EUCAST guidelines.
  • Minimum Inhibitory Concentration (MIC) Testing:
    • MIC is determined using broth microdilution, agar dilution, or automated systems.
    • The MIC is the lowest concentration of cefpirome that inhibits visible bacterial growth.
  • E-test (Gradient Diffusion):
    • A strip with a gradient of cefpirome concentrations is placed on an agar plate inoculated with the bacterial isolate.
    • The MIC is determined where the elliptical growth inhibition zone intersects the strip.

Application:

• Clinical Use:
  • Cefpirome is used to treat:
    • Severe hospital-acquired infections (e.g., bloodstream infections, pneumonia).
    • Neutropenic fever in immunocompromised patients.
    • Complicated urinary tract infections (UTIs).
    • Skin and soft tissue infections caused by susceptible organisms.
    • Infections caused by multidrug-resistant Gram-negative bacteria (excluding carbapenem-resistant organisms).
• Antimicrobial Stewardship:
  • Encourages the targeted use of cefpirome to avoid unnecessary reliance on carbapenems or other last-line agents.
• Epidemiological Surveillance:
  • Tracks resistance trends in Enterobacterales and Pseudomonas aeruginosa.

Cefpirome susceptibility testing is vital for managing serious bacterial infections caused by Gram-negative and some Gram-positive bacteria. Standardized methods, including MIC testing and disk diffusion, provide reliable results.