Cefoperazone Susceptibility Testing 

Cefoperazone is a third-generation cephalosporin antibiotic with a broad spectrum of activity, particularly against Gram-negative bacteria, including Pseudomonas aeruginosa. It also has activity against certain Gram-positive bacteria. Cefoperazone is often combined with sulbactam (a beta-lactamase inhibitor) to enhance its efficacy against beta-lactamase-producing bacteria. Susceptibility testing for cefoperazone is critical to determine its efficacy, especially in the presence of resistance mechanisms such as beta-lactamase production and porin loss.

Content:

• Testing Methods:
  • Disk Diffusion (Kirby-Bauer Method):
    • Disks containing cefoperazone (75 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 or agar dilution methods.
    • The MIC is the lowest concentration of cefoperazone that inhibits visible bacterial growth.
• • Automated Testing Systems:
    • Platforms like Vitek, Phoenix, or MicroScan may include cefoperazone in their susceptibility panels, but validation depends on the system.

Application:

• Clinical Use:
  • Cefoperazone is used for:
    • Complicated urinary tract infections (UTIs).
    • Intra-abdominal infections, often in combination with metronidazole for anaerobic coverage.
    • Respiratory tract infections, including hospital-acquired pneumonia.
• Antimicrobial Stewardship:
  • Promotes the targeted use of cefoperazone to avoid unnecessary reliance on carbapenems or other broad-spectrum agents.
  • Supports de-escalation to narrower-spectrum agents when susceptibility results are available.
• Epidemiological Surveillance:
  • Tracks resistance trends in beta-lactamase-producing organisms, including Pseudomonas aeruginosa and Enterobacterales.

Cefoperazone susceptibility testing is critical for managing infections caused by Gram-negative bacteria, particularly multidrug-resistant Pseudomonas aeruginosa and Enterobacterales. Standardized methods like disk diffusion and MIC testing ensure accurate results. While cefoperazone remains effective against many pathogens, the increasing prevalence of beta-lactamases and carbapenemases necessitates careful interpretation of susceptibility data.