Table 2.

In Vitro Cefiderocol Activity Against Gram-Negative Bacilli With Differing Resistance Mechanisms

Reference	Resistance Mechanism	Isolate Number	Range	MIC50	MIC90
Enterobacterales
	Ambler class A – serine-beta-lactamases
Kohira et al [16]	ESBL	92	<0.125–4	0.125	0.5
Mushtaq et al [14]*	ESBL + porin loss	26	0.125–32	2	8
Kazmierczak et al [12]	KPC	75	0.03–4	1	2
Kohira et al [16]	KPC	47	<0.125–4	0.125	0.5
Mushtaq et al [14]	KPC	56	<0.03–8	0.25	2
Jacobs et al [15]*	KPC-2	355	<0.03–32	1	8
Delgado-Valverde et al [39]	ST512/KPC-3	25	0.25–4	2	4
Delgado-Valverde et al [39]	ST258/KPC-3	25	0.06–4	2	2
Jacobs et al [15]	KPC-3	380	<0.03–64	0.25	2
	Ambler class B – metallo-beta-lactamases
Kazmierczak et al [12]	VIM	27	0.12–4	1	4
Kohira et al [16]	VIM	12	<0.125–16	0.125	0.25
Mushtaq et al [14]	VIM	47	<0.03–8	0.5	4
Kanazawa et al [40]	IMP-6	82	<0.03–2	0.06	1
Kohira et al [16]	IMP	8	<0.125–16	–	–
Mushtaq et al [14]	IMP	15	<0.03–4	0.25	2
Kazmierczak et al [12]*	NDM	12	1–8	4	8
Kohira et al [16]*	NDM	49	<0.125–>16	1	16
Jacobs et al [15]*	NDM	28	0.25–>64	2	8
Mushtaq et al [14]*	NDM	61	0.25–32	4	8
	Ambler class C – cephalosporinases
Mushtaq et al [14]	AmpC + porin loss	25	0.06–2	0.5	2
	Ambler class D – oxacillinases
Delgado-Valverde et al [39]	OXA-48	3	0.06–0.5	–	–
Kazmierczak et al [12]	OXA-48-like	32	0.03–4	0.5	4
Mushtaq et al [14]	OXA-48-like	56	<0.03–8	0.25	2
Jacobs et al [15]	OXA-48-like	7	<0.03–1	0.25	1
	Combination resistance mechanisms
Delgado-Valverde et al [39]	ST11/OXA-48 + CTX-M-15	25	<0.03–4	0.25	2
Delgado-Valverde et al [39]	ST15/OXA-48 + CTX-M-15	25	<0.03–4	0.25	4
Delgado-Valverde et al [39]	ST392/OXA-48 + CTX-M-15	4	0.06–1	–	–
Kazmierczak et al [12]	Carbapenemase negative, meropenem resistant	13	0.008–4	0.12	2
Pseudomonas aeruginosa
	Ambler class A – serine-beta-lactamases
Kazmierczak et al [12]	GES	4	0.12–0.25	–	–
Mushtaq et al [14]	GES	20	0.06–4	0.25	2
Mushtaq et al [14]*	PER	15	0.06–16	1	16
Mushtaq et al [14]	VEB	10	0.5–8	–	–
	Ambler class B – metallo-beta-lactamases
Kazmierczak et al [12]	VIM	26	0.008–2	0.25	2
Mushtaq et al [14]	VIM	30	<0.03–>128	0.25	1
Kazmierczak et al [12]	IMP	4	1–2	–	–
Mushtaq et al [14]*	IMP	25	0.06–16	0.25	8
Mushtaq et al [14]*	NDM	11	1–>128	4	16
Kazmierczak et al [12]	Carbapenemase-negative, meropenem non-susceptible	319	<0.002–4	0.12	0.5
Jacobs et al [15]	Carbapenem-resistant NOS	27	<0.03–1	0.25	0.5
Acinetobacter baumannii
	Ambler class A – serine-beta-lactamases
Kazmierczak et al [12]	GES-type	7	0.25–8	–	–
	Ambler class B – metallo-beta-lactamases
Kazmierczak et al [12]	NDM	2	1–1	–	–
Mushtaq et al [14]*	NDM	20	1–>128	2	16
	Ambler class D – oxacillinases
Delgado-Valverde et al [39]	OXA-23	25	0.06–1	0.25	0.5
Kazmierczak et al [12]	OXA-23	543	<0.002–16	0.12	1
Mushtaq et al [14]*	OXA-23	41	0.06–>128	0.25	16
Delgado-Valverde et al [39]*	OXA-24	25	0.5–16	2	16
Kazmierczak et al [12]	OXA-24	124	0.004–64	0.12	1
Mushtaq et al [14]	OXA-51	19	0.06–16	0.125	0.5
Kazmierczak et al [12]	OXA-58	14	0.06–1	0.06	1
Delgado-Valverde et al [39]	ST2/OXA-58	25	0.06–0.5	0.125	0.5
Delgado-Valverde et al [39]	ST745/OXA-58	5	0.06–0.25	–	–
Mushtaq et al [14]	OXA-58	10	0.06–>128	–	–
Mushtaq et al [14]	OXA-24/40	9	0.25–4
Kazmierczak et al [12]*	Carbapenemase-negative, meropenem non-susceptible	86	0.008–8	0.25	2
Jacobs et al [15]	Carbapenem-resistant NOS	101	<0.03–>63	0.25	1

MICs are determined by broth microdilution using iron-depleted and cation-adjusted Mueller-Hinton broth.

MIC₅₀, MIC at which cefiderocol inhibits growth of 50% of tested isolates.

MIC₉₀, MIC at which cefiderocol inhibits growth of 90% of tested isolates.

MIC₅₀ and MIC₉₀ not determined if <10 isolates.

*MIC 90 exceeding either FDA or EUCAST breakpoint, whichever is higher.

Abbreviations: CTX-M, group of class A extended-spectrum β-lactamases; ESBL, extended-spectrum beta-lactamase; GES, Guiana extended spectrum β-lactamase; IMP, imipenem-hydrolyzing β-lactamase;

KPC, Klebsiella pneumoniae carbapenemase; MIC, minimum inhibitory concentration; NDM, New Delhi metallo β-lactamase; NOS, not otherwise specified; OXA, oxacillin-hydrolyzing β-lactamases; PER: extended-spectrum β-lactamase first discovered in strains of P. aeruginosa; ST, sequence type; VEB, Vietnamese extended-spectrum β-lactamase; VIM, Verona integron-encoded metallo-β-lactamase.