There is line which says that the beta-lactamase resistant penicillins tend to be comparatively lipophilic molecules that do not go inside the gram -ve bacte

There is line which says that the beta-lactamase resistant penicillins tend to be comparatively lipophilic molecules that do not go inside the gram -ve bacteria. But gram -ve bacteria have bilayer of lipid which is hydrophobic(lipophilic) in nature so it will definitely allow the movement of lipophilic molecules over lipophobic molecules So how this lipophilic penicillins are not able to go through gram -ve bacteria?