Ceftibuten Susceptibility Testing 

Ceftibuten is an oral third-generation cephalosporin primarily active against Gram-negative bacteria, with limited activity against Gram-positive organisms. It is often used for treating respiratory tract infections and uncomplicated urinary tract infections (UTIs). Due to the increasing prevalence of beta-lactamase-producing organisms, susceptibility testing is critical to guide the appropriate use of ceftibuten.

Content:

• Testing Methods:
  • Disk Diffusion (Kirby-Bauer Method):
    • Disks containing ceftibuten (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 ceftibuten that inhibits visible bacterial growth.
  • E-test (Gradient Diffusion):
    • A strip with a gradient of ceftibuten concentrations is placed on an agar plate inoculated with the bacterial isolate.

Application:

• Clinical Use:
  • Ceftibuten is commonly used for:
    • Respiratory tract infections, including otitis media, sinusitis, pharyngitis, and bronchitis.
    • Uncomplicated urinary tract infections (UTIs) caused by susceptible Escherichia coli and Proteus mirabilis.
    • Acute bacterial exacerbations of chronic bronchitis.
• Antimicrobial Stewardship:
  • Promotes targeted therapy with ceftibuten, reducing reliance on broader-spectrum antibiotics.
  • Avoids unnecessary use in infections caused by resistant organisms, preserving its efficacy.
• Epidemiological Surveillance:
  • Tracks resistance trends in Enterobacterales and other Gram-negative pathogens.
  • Monitors the prevalence of ESBL-producing and AmpC-producing organisms.

Ceftibuten susceptibility testing is essential for guiding therapy in infections caused by Gram-negative bacteria, particularly in the context of beta-lactamase-mediated resistance. Standardized methods, such as MIC testing and disk diffusion, ensure reliable results.