Table 1. Breakpoints revision in CLSI M100

Ann Clin Microbiol 2023;26:51-57. Introduction to the revised international guidelines on breakpoints for antimicrobial susceptibility testing

Organism	Antimicobial agent	Test/Report group	Tier	Disk diffusion (mm)						MIC (µg/mL)
				2022			2023			2022			2023
				S	I	R	S	I	R	S	I	R	S	I	R
Enterobacterales	Amikacin	B	2	≥ 17	15-16	≤ 14	≥ 20	17-19	≤ 16	≤ 16	32	≥ 64	≤ 4	8	≥ 16
	Gentamicin	A	1	≥ 15	13-14	≤ 12	≥ 18	15-17	≤ 14	≤ 4	8	≥ 16	≤ 2	4	≥ 8
	Tobramycin	A	2	≥ 15	13-14	≤ 12	≥ 17	13-16	≤ 12	≤ 4	8	≥ 16	≤ 2	4	≥ 8
	Plazomicin	–	3				≥ 18	15-17	≤ 14				≤ 2	4	≥ 8
	Amikacin	B	U^†	≥ 17	15-16	≤ 14	≥ 17	15-16	≤ 14	≤ 16	32	≥ 64	≤ 16	32	≥ 64
	Gentamycin	A	–	≥ 15	13-14	≤ 12	–	–	–	≤ 4	8	≥ 16	–	–	–
Pseudomonas aeruginosa	Tobramycin	A	1	≥ 15	13-14	≤ 12	≥ 19	13-18	≤ 12	≤ 4	8	≥ 16	≤ 1	2	≤ 4
	Piperacillin	O	*^‡	≥ 21	15-20	≤ 14	≥ 22	18-21	≤ 17	≤ 16	32-64	≥ 128	≤ 16	32	≥ 64
	Piperacillin-tazobactam	A	1	≥ 21	15-20	≤ 14	≥ 22	18-21	≤ 17	≤ 16/4	32/4-64/4	≥ 128/4	≤ 16/4	32/4	≥ 64/4

†agents reported only on organisms isolated from the urinary tract; ‡designated with an asterisk as ‘other’. Abbreviations: CLSI, Clinical and Laboratory Standards Institute; MIC, minimum inhibitory concentration; S, susceptible; I, intermediate; R, resistant; O, other.