TABLE 1.

Summary of antimicrobial MIC and MBEC values determined for E. coli BW25113 transformed with various qac gene vectors and grown as planktonic (broth), colony (agar), and biofilm (MBEC device) cultures for 24 h at 37°C

Condition and vectora	MIC or MBEC (μg/ml)b
	CPC	CET	BZK	DDAB	CDEB	CTAB	DOM	ET	AC	MV	CHX	ERY	TOB
MICc
Agar (n = 3)
pMS119EH	8	64	16	4	4	64	32	256	80	320	8	64	4
pEmrE	8	64	32	8	8	64	32	>1,024	320	640	8	32	4
pQacE	8	64	32	8	8	128	32	512	160	320	8	64	8
pQacEΔ1	8	64	32	4	4	64	32	256	160	320	8	64	4
pQacF	8	64	32	8	8	64	32	512	160	320	8	64	4
pQacG	8	64	32	8	8	64	32	256	80	320	8	64	8
pQacH	8	64	32	8	8	128	32	512	320	320	8	64	8
Broth (n = 3)
pMS119EH	8–16	8–16	8–16	1.5	8	2	8	NA	NA	512	1	38	4
pEmrE	8–16	8–16	8–16	2	8	4	8	NA	NA	>1,024	2	38	4
pQacE	8–16	8–16	8–16	2	8	4	8	NA	NA	256	2	38	4–8
pQacEΔ1	8–16	8–16	8–16	1.5	8	2	8	NA	NA	512	2	38	4
pQacF	8–16	16–32	8–16	2	8	4	8	NA	NA	256	1	38	4–8
pQacG	8–16	8–16	8–16	2	8	4	8	NA	NA	512	1	38	4–8
pQacH	8–16	8–16	8–16	2	8	2	8	NA	NA	512	1	38	4
MBEC (n = 6)d
pMS119EH	64	32	64	8-16	16	128	32	3,750	64	4,096	128	1,024	4
pEmrE	256	64	256	32	64–128	32	32–64	7,500	512	16,384	256	2,048	8
pQacE	32	64	256	8–16	32	32	32	7,500	256	16,384	512	2,048	32
pQacEΔ1	32	256	64	8–16	21	128	32	3,750	64	16,384	256–512	1,024	8
pQacF	128	128	64	16–32	26	128	32	7,500	149	16,384	128	2,048	16–32
pQacG	256	256	128	32	64	128	32–64	3,750	64	8,129	128	2,048	8
pQacH	256	128	256	32	128	128	32–64	7,500	512	16,384	128	2,048	32

^aAll genes were directionally cloned in the multiple-cloning site of pMS119EH at 5′ XbaI and 3′ HindIII restriction sites.

^bAntimicrobial abbreviations: CPC, cetylpyridinium chloride; CET, cetrimide bromide; BZK, benzalkonium chloride; DDAB, didecyldimethylammonium bromide; CDEB, cetyldimethylethylammonium bromide; CTAB, cetyltrimethylammonium bromide; DOM, domiphen bromide; ET, ethidium bromide; MV, methyl viologen dichloride; CHX, chlorhexidine dichloride; AC, acriflavine; ERY, erythromycin; TOB, tobramycin. Boldface numbers indicate ≤4- or ≥4-fold changes in MIC/MBEC AST values compared to pMS119EH transformants under the same AST growth conditions. NA, data not available because the drug concentration absorbance values exceeded detection thresholds.

^cAST involved 10⁻⁴ dilutions of plasmid-transformed cultures adjusted to an optical density at 600 nm of 1.0 as the starting inoculum in Luria-Bertani medium with 100 μg/ml ampicillin and 0.05 mM isopropyl β-d-1-thiogalactopyranoside (IPTG).

^dShown are results from 24-h biofilms on the MBEC device pegged lid followed by drug incubation for 24 h in LB broth prior to AST.