Penicillin-binding Proteins (PBP) and Lmo0441 (a PBP-like protein) play a role in Beta-lactam sensitivity of Listeria monocytogenes

Table 1 MIC measurements, regression parameters^a and statistical analysis of the dose-response curves illustrated in Figure 1

	AMP			MEM			CFX
	MIC (mg/L)	E_max^b (CI)^c Δlog from original inoculum	R²	MIC (mg/L)	E_max^b (CI)^c Δlog from original inoculum	R²	MIC (mg/L)	_max^b (CI)^c log from original inoculum	R²
EGDe WT	0.125	-1.53 (-1.7 to -1.3)	0.97	0.0625	-1.85 (-2.2 to -1.5)	0.95	8	-3.65 (-4.2 to -3.1)	0.97
ΔPBP4	0.125	-2.51 (-2.7 to -2.3)^d	0.98	0.0625	-2.92 (-3.3 to -2.5)^d	0.98	2	-2.29 (-2.6 to -1.9)^d	0.93
ΔLmo0441	0.125	-1.74 (-1.9 to -1.5)	0.97	0.0625	-2.02 (-2.5 to -1.6)	0.97	2	-1.92 (-2.2 to -1.7)^d	0.95

Ampicillin (AMP), meropenem (MEM) and cefuroxime (CFX) MICs measurements for the parental strain EGDe and ΔPBP4 and ΔLmo0441 mutant strains. MICs of AMP and MEM, with a respective value of 0.125 and 0.0625 mg/L, did not differ between wild type and mutant strains. However, there is a 4-fold increase in MIC of CFX for both mutant strains, which passes from 8 mg/L to 2 mg/L, a finding which is in agreement with previous observations [9].
^a Regression parameters are based on the Hill equation (using a variable slope)
^b Concentration causing maximal activities (E_max values), as obtained from the Hill equation. Values are expressed as a multiple of the respective MIC for a given strain.
^c CI - Confidence Intervals (95%)
^d Significantly different (p < 0.05) from the wild type strain as calculated by F-test

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