TABLE 3.

Binding affinities of PBP 1 for mezlocillin and penicillin G in the Amox^s and Amox^r strains^a

Abx	Phenotype	Control abs.	1× MIC		10× MIC		100× MIC
			Abs.	% Decreaseb	Abs.	% Decrease	Abs.	% Decrease
Mezl	S	2.45 ± 0.03	2.04 ± 0.39	17	0.39 ± 0.19	84	0.07 ± 0.01	97
Mezl	R	2.51 ± 0.14	2.39 ± 0.17	ND	1.37 ± 0.38	45	0.04 ± 0.01	98
Pen G	S	2.87 ± 0.02	2.89 ± 0.05	ND	2.41 ± 0.14	16	0.59 ± 0.23	79
Pen G	R	2.57 ± 0.04	2.68 ± 0.12	ND	2.57 ± 0.11	ND	0.48 ± 0.17	81

^aH. pylori membrane fractions were preincubated with either mezlocillin or penicillin G at 1, 10, or 100 times the MIC prior to labeling with 4 μg of bio-Amox per ml, separated by SDS-PAGE, and visualized on Western blots. These blots were then quantitatively examined by laser densitometry. Control values represent bio-Amox labeling without preincubation with a competing antibiotic. Abx, antibiotic treatment; Abs., absorbance; Mezl, mezlocillin; Pen G, penicillin G; S, Amox^s H. pylori; R, Amox^r H. pylori; ND, decrease of ≤5%. Data represent the means ± standard errors of the means determined from three separate experiments. 

^b% Decrease, percent decrease in absorbance compared to control.