TABLE 5.

Affinity of cefiderocol and ceftazidime for penicillin-binding proteins of E. coli NIHJ JC-2, K. pneumoniae SR22291, P. aeruginosa ATCC 27853, and A. baumannii ATCC 17978

PBP	IC50 (μg/ml)
	E. coli NIHJ JC-2		K. pneumoniae SR22291		P. aeruginosa ATCC 27853		A. baumannii ATCC 17978 a
	Cefiderocol	Ceftazidime	Cefiderocol	Ceftazidime	Cefiderocol	Ceftazidime	Cefiderocol	Ceftazidime
PBP1a	3.80	>4	2.80	1.50	0.85	3.62	1.05	0.91
PBP1b	3.37	>4	3.50	2.30	>4	>4
PBP2	2.12	>4	0.063	0.41	>4	>4	2.31	>64
PBP3	0.04	0.45	0.062	0.22	0.06	0.09	0.67	1.78
PBP4	NCb	>1	0.28	3.60	>4	>4	NDc	ND

^aThe IC₅₀s cannot be divided into separate values for PBP1a and PBP1b.

^bNC, not calculated. Cefiderocol inhibited 63% of PBP4 at 4 μg/ml, but the sigmoid curve did not fit and the IC₅₀ cannot be calculated.

^cND, not detected.