Related Experiment Videos
Evaluation of four anti-microbic susceptibility testing systems for gram-negative bacilli
American Journal of Clinical Pathology
|November 1, 1986
Summary
Comparing antimicrobial susceptibility testing systems, the study found minimal discrepancies. Automated and frozen methods showed high agreement with reference standards, crucial for accurate clinical decisions.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Pharmaceutical Science
Background:
- Accurate antimicrobial susceptibility testing (AST) is vital for guiding effective antibiotic therapy.
- Several AST methods exist, including broth dilution, automated systems, and disk diffusion, each with varying performance characteristics.
- Evaluating the concordance of different AST systems against a reference method is essential for clinical laboratories.
Purpose of the Study:
- To compare the performance of five antimicrobial susceptibility testing systems against a reference broth dilution method.
- To identify the number of major and very major discrepancies for each tested system.
- To assess the overall agreement and identify specific antimicrobial-organism combinations contributing to discrepancies.
Main Methods:
- Two hundred clinical isolates (100 resistant strains, 100 fresh isolates) were tested.
- Five AST systems were evaluated: MicroScan, Pasco (frozen MIC systems), AMS Vitek (automated MIC system), disk diffusion, and reference broth dilution.
- A total of 1,600 antimicrobial-organism combinations were analyzed.
Main Results:
- Pasco and MicroScan systems showed no major discrepancies compared to the reference method.
- Automated MIC (AMS) and disk diffusion systems had 7 and 2 major discrepancies, respectively.
- Very major discrepancies were highest for AMS (11) and disk diffusion (9), with significant contributions from aminoglycosides and second-generation cephalosporins (especially cefamandole).
Conclusions:
- Frozen MIC systems (MicroScan, Pasco) demonstrated excellent agreement with the reference method, with minimal discrepancies.
- Automated systems and disk diffusion showed a higher rate of discrepancies, particularly with specific drug classes.
- Overall essential agreement exceeded 98.8% across all systems, indicating general reliability but highlighting areas for improvement in AST accuracy.