TABLE 1.

Phenotypic confirmatory disk diffusion test results using cefotaxime and ceftazidime disks, with and without clavulanic acid, that were stored frozen for up to 14 days^a

Day	Zone diam (mm)
	E. coli LPTP 9711 (ESBL producing)						E. coli 25922 (ESBL negative)
	CTX	CTX-CL	Difference between CTX and CTX-CL	CAZ	CAZ-CL	Difference between CAZ and CAZ-CL	CTX	CTX-CL	Difference between CTX and CTX-CL	CAZ	CAZ-CL	Difference between CAZ and CAZ-CL
1	22	34	12	11	28	17	33	35	2	31	32	1
2	22	36	14	11	29	18	32	32	0	30	30	0
3	22	35	13	11	29	18	32	35	3	30	31	1
4	22	35	13	12	30	18	34	34	0	31	30	−1
5	21	34	13	11	29	18	35	36	1	31	30	−1
6	22	35	13	11	29	18	34	35	1	31	32	1
7	23	36	13	12	30	18	35	36	1	31	32	1
8	22	35	13	13	29	16	35	36	1	31	30	−1
9	24	36	12	13	30	17	35	33	−2	31	31	0
10	22	34	12	12	29	17	33	34	1	32	31	−1
11	21	35	14	12	29	17	33	35	2	30	31	1
12	22	35	13	12	30	18	34	34	0	31	32	1
13	22	36	14	12	30	18	34	34	0	30	31	1
14	22	36	14	12	30	18	34	34	0	32	30	−2
Mean diam		35.1	13.1		29.4	17.6		34.5	0.7		30.9	−0.1
SD		0.8	0.7		0.6	0.7		1.2	1.1		0.8	1.0
r²		0.11	0.10		0.35	0.25		0.10	0.13		0.01	0.10
P value		0.25	0.27		0.02	0.85		0.81	0.20		0.97	0.27

CTX, cefotaxime; CAZ, ceftazidime; CL, clavulanic acid.