Define Major Error in AST method comparison.

Define Major Error in AST method comparison.

• A. A susceptible result by the test when the reference method shows resistant.
• B. A resistant result by the test when the reference method shows susceptible.
• C. A discrepancy involving intermediate vs resistant.
• D. A susceptible result by the test when the reference method shows resistant.

Answer: (D)

In AST method comparison, the important idea is how the test’s category (susceptible or resistant) agrees or disagrees with the reference method, and how that disagreement could affect treatment decisions. A major error occurs when the test method labels an organism as resistant to an antibiotic, but the reference method shows it is susceptible. This misclassification can lead clinicians to withhold an antibiotic that would actually be effective, potentially compromising patient care. For context, the opposite misclassification—where the test says susceptible but the reference shows resistance—would be even more dangerous in practice and is categorized as a very major error, a higher-risk type of discrepancy. Minor errors involve other mismatches, such as discrepancies that include intermediate results.

In AST method comparison, the important idea is how the test’s category (susceptible or resistant) agrees or disagrees with the reference method, and how that disagreement could affect treatment decisions. A major error occurs when the test method labels an organism as resistant to an antibiotic, but the reference method shows it is susceptible. This misclassification can lead clinicians to withhold an antibiotic that would actually be effective, potentially compromising patient care.

For context, the opposite misclassification—where the test says susceptible but the reference shows resistance—would be even more dangerous in practice and is categorized as a very major error, a higher-risk type of discrepancy. Minor errors involve other mismatches, such as discrepancies that include intermediate results.