TABLE 5.

β-Lactamase genes and other potential resistance mechanisms identified in cefiderocol-resistant P. aeruginosa isolates (n = 10)^a,b

Isolate	Country	FDC MIC (mg/L)	ST	Potential resistance mechanism(s) identified
				β-Lactamasec	ftsl	oprD	piuA	piuC	pirA-like	pvdS
1	France	8	4291d	OXA-396; PDC-543	WT	No gross disruption	Gene not found	Gene not found	A370T	WT
2	France	4	773	OXA-395; PDC-16; NDM-1	WT	No gross disruption	Q34H	R201H	A370T	V180L; H182N
3	France	8	235	OXA-19; OXA-488; PDC-35	WT	No gross disruption	piuD	R201H	S20N; T235I; A370T	V180L; H182N
4	Germany	4	298	OXA-848; PDC-219	A244T	Gross disruption	piuD	R201H	Gross disruption	V26A
5	Germany	8	4290d	OXA-1124; PDC-86	WT	No gross disruption	Q34H	T10S; R201H	A13V; A370T	V180L; H182N
6	Italy	8	708	OXA-50; PDC-446	WT	No gross disruption	Q34H	WT	R7H; A370T; Q620K	V180L; T181A; H182N
7	Italy	16	4305d	OXA-488; PDC-337	WT	No gross disruption	Q34H	R201H	A370T	WT
8	Spain	4	4304d	OXA-1022; PDC-46	V137M	Gross disruption	Q34H	R201H	Y2S; A370T	WT
9	Spain	4	4306d	OXA-1188; PDC-5	WT	No gross disruption	piuD	V104I	A370T	V180L; T181A; H182N; R186P
10	UK	4	4283d	OXA-1135; PDC-63	WT	No gross disruption	Gene not found	D49E; E125A; R198Q; V203I	T144S; A208T; A370T; T480A	WT

^a FDC, cefiderocol; MBL, metallo-β-lactamase; NDM, New Delhi MBL; OXA, oxacillinase; PDC, Pseudomonas-derived cephalosporinase; ST, sequence type; UK, United Kingdom; WT, wild type.

^b Data were generated by whole-genome sequencing. A gene was considered to have a gross disruption if the coding sequence carried a nonsense mutation, frameshift, indels of >20 codons, or ablation of the canonical stop or start codons without a replacement immediately adjacent and in-frame. Genes were listed to be not found if a BLAST search with the reference gene yielded no hit with E-value <1E-25. Non-β-lactamase genes that were either found to have gross disruptions or mutations or were not found are shown in gray.

^c Data shown are a curated summary.

^d Indicates a novel ST.