AMB Express

Table 1 Zones of growth inhibition for E. coli and L. acidophilus

From: 600-ns pulsed electric fields affect inactivation and antibiotic susceptibilities of Escherichia coli and Lactobacillus acidophilus

Pulse #	E. coli								L. acidophilus
	Kanamycin				Tobramycin				Vancomycin				Ampicillin–sulbactam
	nsPEF	SD	TE	SD	nsPEF	SD	TE	SD	nsPEF	SD	TE	SD	nsPEF	SD	TE	SD
13.5 kv cm⁻¹
Sham	16 (I)	0.2	16 (I)	0.2	11 (R)	0.6	11 (R)	0.6	13 (R)	0.6	13 (R)	0.6	14 (I)	0.6	14 (I)	0.6
1	16 (I)	0	16 (I)	0	11 (R)	0	11 (R)	0.6	13 (R)	0	14 (R)	0	14 (I)	1	14 (I)	0
5	16 (I)	0	16 (I)	0	11 (R)	0	11 (R)	0.6	13 (R)	1	14 (R)	0.6	15 (I)	1	14 (I)	0.6
10	16 (I)	0	16 (I)	0	11 (R)	0.6	11 (R)	0.5	13 (R)	1	14 (R)	0.6	15 (I)	1	14 (I)	1
100	16 (I)	0	16 (I)	0	12 (R)	0	12 (R)	0.6	14 (R)	1	14 (R)	0	16 (S)	0.7	14 (I)	0
1000	18 (S)	0.3	16 (I)	0	12 (R)	0	11 (R)	0.6	16 (I)	1	14 (R)	0.3	19 (S)	1	14 (I)	0.6
18.5 kv cm⁻¹
Sham	16 (I)	0.2	16 (I)	0.2	11 (R)	0.6	11 (R)	0.6	13 (R)	0.6	13 (R)	0.6	14 (I)	0.6	14 (I)	0.6
1	17 (I)	1	16 (I)	0.3	11 (R)	0.6	12 (R)	0.3	13 (R)	0.6	14 (R)	0	14 (I)	0	14 (I)	0.6
5	18 (S)	0	16 (I)	0.6	12 (R)	0	12 (R)	0.6	13 (R)	0.6	14 (R)	0	14 (I)	1	14 (I)	0.3
10	19 (S)	0.6	16 (I)	0	12 (R)	0	12 (R)	0	13 (R)	0	14 (R)	1	14 (I)	1	14 (I)	0
100	20 (S)	0	16 (I)	0.6	12 (R)	0.6	12 (R)	0.6	14 (R)	1	14 (R)	0.8	16 (S)	0	14 (I)	1
1000	22 (S)	0	16 (I)	0	14 (I)	0.6	11 (R)	0	15 (I)	0	14 (R)	0	19 (S)	1.4	14 (I)	0
23.5 kv cm⁻¹
Sham	16 (I)	0.2	16 (I)	0.2	11 (R)	0.6	11 (R)	0.6	13 (R)	0.6	13 (R)	0.6	14 (I)	0.6	14 (I)	0.6
1	17 (I)	0.6	16 (I)	0	11 (R)	0	11 (R)	0.6	14 (R)	0	14 (R)	0.3	14 (I)	2	14 (I)	0
5	17 (I)	0	16 (I)	0.6	11 (R)	1.2	11 (R)	0.6	15 (I)	0.6	14 (R)	0.6	15 (I)	0.8	14 (I)	0.3
10	19 (S)	1	16 (I)	0	12 (R)	1	11 (R)	0.6	15 (I)	0.6	14 (R)	0.3	16 (S)	0.6	14 (I)	0.3
100	22 (S)	0.5	16 (I)	0	16 (S)	0	12 (R)	0.5	15 (I)	1	14 (R)	0.6	18 (S)	1	14 (I)	0
1000	*	*	*	*	*	*	*	*	*	*	*	*	*	*	*	*

Following a 13.5, 18.5 or 23.5 kV cm⁻¹ 600-ns PEF and its respective TE, E. coli and L. acidophilus were exposed to the following antibiotic-soaked discs: kanamycin (30 µg) and tobramycin (10 µg) and vancomycin (30 µg) and ampicillin/sulbactam (10/10 µg), respectively. Measured zones of growth inhibition (diameter, mm) are reported. Values represent the mean of 3 replicates, the standard deviation (SD) of each value is provided. Susceptibility is expressed as R (resistant), I (intermediate) or S (susceptible). No observable growth is indicated by an asterisk (*)

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