Table 1.

Breakpoint interpretations applied to categorize P. aeruginosa antimicrobial susceptibility testing results for novel therapies

Agent	CLSI breakpoints						EUCAST breakpoints				FDA breakpoints
	MIC (mg/L)			DD (mm)			MIC (mg/L)		DD (mm)		MIC (mg/L)			DD (mm)
	S	I	R	S	I	R	S	R	S	R	S	I	R	S	I	R
Ceftolozane–tazobactam	≤ 2/4	4/4	≥ 8/4	≥ 21	18–20	≤ 17	≤ 4	> 4	≥ 23	< 23	M-100 standard is recognized
Ceftazidime–avibactam	≤ 8/4	–	≥ 16/4	≥ 21	–	≤ 20	≤ 8	> 8	≥ 17	< 17	M-100 standard is recognized
Imipenem–relebactam	≤ 2/4	4/4	≥ 8/4	≥ 23	20–22	≤ 19	≤ 2	> 2	≥ 22	< 22	M-100 standard is recognized
Cefiderocol	≤ 4	8	≥ 16	≥ 18	13–17	≤ 12	≤ 2	> 2	≥ 22	< 22	≤ 1	2	≥ 4	≥ 25	19–24	≤ 18

CLSI Clinical and Laboratory Standards Institute, EUCAST European Committee on Antimicrobial Susceptibility Testing, FDA US Food and Drug Administration, MIC minimum inhibitory concentration, DD disk diffusion, S susceptible, I intermediate, R resistant [51–53]