WHAT IS THE ACCEPTABLE ACCURACY OF A
SUSCEPTIBILITY TEST METHOD?
When assessing the accuracy of various susceptibility testing
methods as compared to standard reference methods, the terms
very major and major errors have been used to describe false-
susceptible or false-resistant results, respectively. In evaluations
of new susceptibility testing methods it is important to examine
a representative number of strains that are resistant to various
drugs to verify the ability of the new test to detect resistance
and to test a number of susceptible strains to determine the
rate of major errors that might be expected in a typical clinical
laboratory setting [16, 21]. To be cleared for marketing in the
United States, the FDA requires that very major errors attrib-
utable to a test device should be !1.5% for individual species/
drug comparisons, major errors should not exceed 3%, and an