Table 2.

Isolates exhibiting ATM/AVI MIC results ≥4 mg/L selected for further characterization and main resistance mechanisms documented

Collection number	Organism	MIC (mg/L)		MLST	β-lactamase genes	mRNA expressiona		Amino acid alterations
		ATM/AVI	CAZ/AVI			AcrA	AmpC	OmpF/OmpK35	OmpC/OmpK36	PBP3
1108470	E. coli	8	2	410	CMY-42, CTX-M-15, OXA-1	3.6	1.2	WT	WT	R333insYRIK
1108523	E. coli	8	2	410	CMY-42, OXA-1	3.8	<1	WT	L14Q	R333insYRIK
1108694	E. coli	8	2	410	CMY-141	2.7	<1	WT	G137D	R333insYRIK
1114251	E. coli	16	8	410	CMY-42, CTX-M-15, OXA-1, TEM-1	3.5	<1	WT	WT	R333insYRIK
1114255	E. coli	8	8	410	OXA-48, CMY-42, CTX-M-14, TEM-190	2.3	<1	WT	WT	R333insYRIK
1118669	E. coli	4	>32	410	NDM-5, OXA-181, CMY-2, CTX-M-15, OXA-1, TEM-1	2.4	<1	WT	R199L	R333insYRIN
1116284	E. coli	8	4	405	CTX-M-15, OXA-1	<1	<1	N258X	WT	R333insYRIK
1128667	E. coli	4	1	405	CTX-M-55, OXA-1	<1	<1	N258X	WT	R333insYRIK
1130864	E. coli	8	8	405	CTX-M-15, OXA-1	<1	<1	N258X	WT	R333insYRIK
1116957	E. coli	8	2	38	CMY-42, OXA-1	<1	<1	WT	WT	R333insYRIK
1126350	E. coli	16	4	617	CMY-42, CTX-M-27	4.5	<1	WT	WT	R333insYRIN
1122568	K. pneumoniae b	8	16	872	PER-2, SHV-11	1.1	NA	Y286X	WT	M6T, A33V, V41I, L370I, Q374K, H396R, E434A, I447M, N455S, L577Q, A578G
1125511	K. pneumoniae b	8	4	15	DHA-1, SHV-28	5.5	NA	A119X	WT	Y432C
1116221	K. pneumoniae b	>16	16	273	DHA-1, LAP-2, SHV-11, TEM-1	6.2	NA	WT	Y43X	WT
1102685	E. cloacae	4	1	350	ACT-27	<1	3667	A19S, S159L, Y199F, E200D, Y208L, E224K, G225A, G234E, L235M, Y236H, T243K, N276A, Q276A, F277H, D278_F279insENT	P177A	G306V
1108008	E. cloacae	4	4	121	ACT-25, CTX-M-15, OXA-1, TEM-1	<1	3060	WT	WT	WT
1118254	E. cloacae	16	2	78	ACT-24, SHV-12, TEM-1	<1	570	WT	P177A, D188E	E258_S259insE

ATM/AVI, aztreonam/avibactam; CAZ/AVI, ceftazidime/avibactam.

^aReported expression results are relative to a control isolate.

^bK. pneumoniae isolates had WT sequences of OmpK37.