Table 3.

Resistance to CAZ-AVI increased in a stepwise manner following passage with CAZ-AVI.

Strain ID	Minimum inhibitory concentration (MIC) of each passage (mg/L)
	0	2	4	6	8	10	12	14	16	18	20	22	24	26	28	30	32	34	36	38	40	42	44	46	48	50
ATCC 700603a	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5
220	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	8	8	8	4	8	4	8	8	8
1419	4	16	16	8	8	16	16	16	32	32	32	32	32	64	32	32	32	32	32	64	32	32	32	32	64	128
14192	4	8	16	32	16	32	32	16	32	32	32	32	32	32	32	32	32	32	32	32	32	32	32	32	32	32
BL94	2	2	2	8	8	8	8	16	16	16	16	32	16	16	16	16	16	16	16	16	16	16	16	16	16	16
1295	4	8	4	4	4	4	4	4	4	8	4	4	4	8	8	4	4	8	4	4	8	8	8	8	8	8
BL18	4	4	8	8	8	8	8	16	16	16	16	16	16	16	16	16	16	32	16	32	16	16	16	16	32	32
BL152	4	4	8	8	8	16	8	8	8	8	16	8	16	8	16	16	16	16	32	32	32	32	32	32	32	32
84082	4	4	4	8	8	8	8	8	8	8	8	16	8	16	8	8	8	16	16	16	32	32	64	128	128	128
P77	2	2	2	4	4	2	4	4	2	2	2	2	2	2	2	2	2	4	2	2	2	4	4	8	16	16
C4	2	4	2	4	4	8	4	8	8	8	8	8	8	16	8	16	8	16	16	16	16	16	16	16	16	16
Q38	1	2	64	64	64	64	64	64	64	64	64	64	64	64	64	64	128	64	128	128	64	128	128	128	128	128
Q35	0.5	1	1	2	2	2	1	2	1	2	2	1	1	2	2	2	2	2	2	4	2	2	2	2	2	16
P152	0.25	0.5	0.5	0.5	0.5	0.5	1	2	2	2	4	1	4	2	1	2	2	2	4	4	4	4	4	4	4	4
Q30	2	2	1	2	1	1	1	2	1	2	2	1	2	2	2	2	2	2	2	2	2	2	2	2	2	16

^aATCC 700603, the recommended strain by the Clinical & Laboratory Standards Institute for the MIC determination of CAZ-AVI, was passaged alongside the test strains in LB broth without antibiotics, acting as a negative control.