Help..? Gram-positive bacteria question?

Question

why are gram-positive bacteria typically more resistant than gram-negative bacteria to antibiotics, that disrupt plasma membranes, such as polymyxin B?

Thanks :)

Answer 1

Polymyxins are antibiotics, with a general structure consisting of a cyclic peptide with a long hydrophobic tail. They disrupt the structure of the bacterial cell membrane by interacting with its phospholipids. They are produced by the Gram-positive bacterium Bacillus polymyxa and are selectively toxic for Gram-negative bacteria due to their specificity for the lipopolysaccharide molecule that exists within many Gram-negative outer membranes.

Answer 2

Gram-positive bacteria lack the membrane structures that such antibiotics target.