TABLE 1.

Comparison of MICs of ceftolozane-tazobactam against P. aeruginosa (n = 90) via Etest and broth microdilution

Method	% of isolates meeting breakpointa			No. positive/total no. (%)
	S	I	R	EAb	CAc	VMEd	MEe	mEf
Etest	92.2	1.1	6.7	68/90 (75.5)	80/90 (88.8)	6/12 (50)	2/76 (2.6)	3/90 (3.3)
Broth microdilution	84.4	2.2	13.3

^aClinical and Laboratory Standards Institute (CLSI) breakpoints for ceftolozane-tazobactam: susceptible (S), ≤4/4 μg/ml; intermediate (I), 8/4 μg/ml; and resistant (R), ≥16/4 μg/ml, respectively.

^bEA, essential agreement; agreement within ±1 2-fold dilution of the Etest to BMD.

^cCA, categorical agreement; agreement of interpretative results (susceptible, intermediate, and resistant) between Etest and BMD.

^dVME, very major error; susceptible by Etest and resistant by BMD.

^eME, major error; resistant by Etest and susceptible by BMD.

^fmE, minor error; reported as intermediate by Etest when susceptible or resistant by BMD or vice versa.