Statistical properties and inference of the antimicrobial MIC test.
A common method for measuring the drug-specific minimum inhibitory concentration (MIC) of an antibacterial agent is via a two-fold broth dilution test known as the MIC test. Because this procedure implicitly rounds data upward, inference based on unadjusted measurements is biased and overestimates bacterial resistance to a drug. We detail this test procedure and its associated bias, which, in many cases, has an expected value of approximately 0.5 on the log(2) scale. In addition, new bias-corrected estimates of resistance are proposed. A numeric example is used to illustrate the extent to which the traditional resistance estimate can overestimate the true proportion of resistant strains, a phenomenon which is remedied by using the proposed estimates.
Annis
David H
DH
Operations Research Department, Naval Postgraduate School, Monterey, CA 93943-5219, USA. annis@nps.edu
Craig
Bruce A
BA
D015982:Bias; D001699:Biometry; D003627:Data Interpretation, Statistical; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000302:isolation & purification; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data*; D015233:Models, Statistical; D011786:Quality Control; D013211:Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000302:isolation & purification