Table 1.

E. faecium isolates investigated in this study and results of phenotypic cell membrane studies

Isolate	Time point of isolation from blood	Daptomycin MIC (μg/ml)	Mean cytochrome c bindingc ± SD	Mean polarization indexd ± SD	Mean cell wall thicknesse ± SD	% of cells with septum formation	Mean % survival in presence of LL37 ± SD
5938	Initial	192	0.378 ± 0.001	0.232 ± 0.011	33.6 ± 4.6	57.8a	75.3 ± 4.6a
8019	+4 mo	4	0.363 ± 0.009	0.232 ± 0.018	33.6 ± 4.5	46.6	50.3 ± 6.0
5994	+8 mo	32	0.413 ± 0.003	0.224 ± 0.008	37.3 ± 5.5a	50.4	108 ± 9.4b

^aSignificantly different (P < 0.05) from strain 8019.

^bSignificantly different (P < 0.05) from both strains 8019 and 5938.

^cCytochrome c binding results are expressed as units of optical density at 530 nm of unbound cytochrome c in supernatant.

^dThe polarization index is expressed as degree of fluorescence polarization (4).

^eCell wall thickness is expressed in nm.