TABLE 2.

Correlation between MICs determined by logistic regression of molecular antimicrobial resistance determinants and phenotypically determined MICs

Antimicrobial	Data seta	No. of isolates matching MIC dilutions ofb:							% ±1 doubling dilution	Sensitivity (%)d	Specificity (%)d	% MIC interpretive errorsc
		>−2	−2	−1	0	+1	+2	>2				MI	MA	VMA
Ceftriaxone	Canada	0	48	612	363	65	7	0	95.0	NA	100	NB	0	0
	UK/USA	18	61	157	133	51	9	2	79.1	NA	100	NB	0	0
Cefixime	Canada	0	23	204	615	228	22	3	95.6	NA	100	NB	0	0
	UK/USA	10	20	119	126	117	36	3	84.0	NA	100	NB	0	0
Azithromycin	Canada	16	73	187	754	60	2	3	91.4	99.7	81.2	NB	7.7	0.2
	UK/USA	12	14	73	114	134	77	7	74.5	77.3	99.8	NB	0.2	1.2
Ciprofloxacin	Canada	13	70	297	512	181	19	3	90.4	100	100	0.5	0	0
	UK/USA	7	14	31	258	106	5	10	91.7	100	98.8	1.9	0.5	0
Tetracycline	Canada	0	20	386	631	58	0	0	98.2	100	100	13.3	0	0
	UK/USA	8	15	101	152	127	22	6	88.2	99.7	88.0	19.0	0.7	0.2
Penicillin	Canada	13	67	423	487	101	4	0	92.3	100	NA	13.9	0	0
	UK/USA	60	53	125	106	72	15	0	70.3	100	NA	34.1	0.2	0
Overall	Canada	42	301	2,109	3,362	693	54	9	93.8	99.9	97.1	4.6	1.3	0.03
	UK/USA	115	117	606	889	607	164	28	81.3	99.2	99.5	9.2	0.3	0.2

^aCanadian validation data set, n = 1,095, and UK/U.S. international data set from Eyre et al. (28), n = 431.

^bThe number of isolates with MIC_pred and MIC_pheno values that differ by the number of 2-fold dilutions.

^cThe percentage of isolates with minor (MI), major (ME), and very major (VME) interpretative errors for susceptibilities. NB, no CLSI intermediate resistance interpretative breakpoints for these antimicrobials.

^dNA, too few isolates available with resistant or susceptible interpretative breakpoints were available to provide meaningful specificity or sensitivity values, respectively.