Interpretive standards and quality control guidelines for cefpiramide disk susceptibility tests

Area of Science:

• Microbiology
• Clinical Pharmacy
• Antibiotic Resistance

Background:

• Accurate antibiotic susceptibility testing (AST) is crucial for guiding effective treatment strategies.
• Cefpiramide is a cephalosporin antibiotic used to treat various bacterial infections.
• Standardized disk diffusion methods are widely employed for AST, but require validation for new antimicrobial agents or disk concentrations.

Purpose of the Study:

• To evaluate the performance of 30- and 75-micrograms cefpiramide disks in disk susceptibility tests.
• To establish quality control parameters and recommend appropriate zone size interpretive criteria for cefpiramide disk diffusion testing.
• To provide evidence-based recommendations for the clinical laboratory use of cefpiramide disks.

Main Methods:

• Disk susceptibility tests were performed on 614 bacterial isolates using cefpiramide disks of 30- and 75-micrograms concentrations.
• Bacterial isolates were tested against cefpiramide to determine their susceptibility profiles.
• Minimum Inhibitory Concentration (MIC) values were correlated with zone diameters obtained from disk diffusion tests.

Main Results:

• The study evaluated the efficacy of two different cefpiramide disk concentrations against a large panel of bacterial isolates.
• Recommended zone size standards were proposed: ≥19 mm for susceptible (MIC ≤32 µg/ml) and ≤15 mm for resistant (MIC ≥128 µg/ml) using 75-micrograms disks.
• Quality control parameters for these disk tests were assessed and control limits were suggested.

Conclusions:

• The 75-micrograms cefpiramide disk test is a reliable method for determining bacterial susceptibility.
• The proposed zone size standards provide clear interpretive criteria for cefpiramide's clinical utility.
• Implementation of these validated disk diffusion methods can aid in optimizing antibiotic therapy and combating antimicrobial resistance.