Table 3. Bacterial Contact Killing of Gram-Negative Strains on Hyperbranched QAC Coatings on PDMS, Carried Out with a Petrifilm Assay^a.

		bacterial challenge CFU/sample
	sample	102	103	104	% reduction
		E. coli ATCC 1110
1	control (PDMS)	63 ± 5	b	b
1a	HBP-PEI+	0	6 ± 2	43 ± 4	99.6
		E. coli Hu 734
2	control (PDMS)	73 ± 5	b	b
2a	HBP-PEI+	12 ± 7	140 ± 16	d	86.0
2b	control + EDTAb	76 ± 8	b	b
2c	HBP-PEI+ + EDTAb	2 ± 2	12 ± 4	38 ± 8	99.6
		E. coli ATCC 15597
3	control (PDMS)	65 ± 6	b	b
3a	HBP-PEI+	6 ± 3	65 ± 8	d	93.5
3b	control + EDTAb	76 ± 4	b	b
3c	HBP-PEI+ + EDTAb	0	3 ± 2	41 ± 5	99.6
		P. mirabilis 28 cii
4	control (PDMS)	83 ± 4	b	b
4a	HBP-PEI+	65 ± 5	d	d	35
4b	control + EDTAb	82 ± 3	b	b
4c	HBP-PEI+ + EDTAb	17 ± 6	51 ± 7	55 ± 4	99.5
		P. mirabilis 296
5	control (PDMS)	70 ± 5	b	b
5a	HBP-PEI+	34 ± 6	110 ± 8	d	d
5b	control + EDTAb	74 ± 3	b	b
5c	HBP-PEI+ + EDTAb	6 ± 3	27 ± 5	35 ± 8	99.7

^aAll experiments were performed in triplicate.

^bEDTA, ethylenediaminetetraacetic acid.

^cNot measured.

^dTMTC, too many to count.