TABLE 2.

Clones, their phenotypes, and the corresponding enzymes obtained from amino acid substitution in the CTX-M-9 enzyme during three cycles of mutagenesis

Cycle of mutagenesis	Clone	Resistance phenotype	Enzyme	Substitution(s)
First (round A)	A1	1a	M-A1	D240G
	A2	1	M-A2	D240G, V29A
	A3	1	M-A3	D240G, I173T
	A4	2b	M-A4	L169Q
	A5	2	M-A5	P167S, N106S
	A6	2	M-A6	P167S
	A7	2	M-A7	D179G, N106S, T86A
	A8	2	M-A8	R276S, A231V, R164H
Second (round B)	A1B1	1	M-A1B1	D240G, R276H, Q87L
	A1B2	1	M-A1B1	D240G, A219D
	A4B1	2	M-A4B1	D240G, L169Q
	A5B1	2	M-A5B1	P167S, N106S, T159S
	A6B1	2	M-A6B1	P167S, A109T
	A7B1	2	M-A7B1	D179G, N106S, T86A, A231V, T165I
	A7B2	2	M-A7B2	D179G, N106S, T86A, A231V
	A7B3	2	M-A7B3	D179G, N106S, T86A, R276H
	A8B1	2	M-A8B1	R276S, A231V, R164H, P167S
	A8B2	2	M-A8B2	R276S, A231V, R164H, P167H
	A8B3	2	M-A8B3	R276S, A231V, R164H, G289E, Q188R, D179N
	A8B4	2	M-A8B4	R2768, A231V, R164H, D179Y
Third (round C)	A1B1C1	1	M-A1B1C1	D240G, R276H, Q87L, H112Y, T230I, A231V
	A1B2C1	2	M-A1B2C1	D240G, A219D, G289W, H197R, L169M
	A5B1C1	2	M-A5B1C1	P167S, N106S, T159S, T171S, T209S
	A5B1C2	2	M-A5B1C2	P167S, N106S, T159S, A140V, A231V
	A6B1C1	2	M-A6B1C1	P167S, A109T, G146R, T227A, Q254P
	A6B1C2	2	M-A6B1C2	P167S, A109T, E166V
	A6B1C3	2	M-A6B1C3	P167S, A109T, E201D
	A6B1C4	2	M-A6B1C4	P167S, A109T, A231V
	A6B1C5	2	M-A6B1C5	P167S, A109T, A172V
	A6B1C6	2	M-A6B1C6	P167S, A109T, A77V, P268A

^aResistance phenotype 1 exhibits similar MICs for cefotaxime and ceftazidime.

^bResistance phenotype 2 exhibits higher MICs for ceftazidime than for cefotaxime.