. 2021 Apr;73(2):679–728. doi: 10.1124/pharmrev.120.000020

TABLE 2.

MIC breakpoints for colistin and polymyxin B established by CLSI (2020) and EUCAST (2021) guidelines

	MIC breakpoints
	CLSI			EUCAST
	S	I	R	S	I	R
Colistin	mg/l
Enterobacterales	— ^a	≤2	≥4	≤2	—^a	>2
P. aeruginosa (CLSI) Pseudomonas spp. (EUCAST)	—^a	≤2	≥4	≤2	—^a	>2
Acinetobacter spp.	—^a	≤2	≥4	≤2	—^a	>2
Polymyxin B
Enterobacterales	—^a	≤2	≥4	—^a	—^a	—^a
Pseudomonas spp.	—^a	≤2	≥4	—^a	—^a	—^a
Acinetobacter spp.	—^a	≤2	≥4	—^a	—^a	—^a

I, intermediate; R, resistant; S, susceptible.

^{^a}

Not determined.