Penicillin tolerance and modification of lipoteichoic acid associated with expression of vancomycin resistance in VanB-type Enterococcus faecium D366.

Induction of vancomycin resistance in Enterococcus faecium D366, which exhibits a VanB-type resistance, as well as its constitutive expression in MT9, a derivative of D366, was associated with penicillin tolerance as shown by decreased lysis and killing of the cells. This phenomenon was linked neither to decreased expression of the different autolysins nor to their decreased lytic activity on the different cell walls. The only change observed was that almost twice the normal amount of D-alanine was attached to the lipoteichoic acid.