It differs from penicillin G , or benzylpenicillin , only by the presence of an amino group .
Ampicillin is able to penetrate Gram - positive and some Gram - negative bacteria .
Ampicillin differs from penicillin G , or benzylpenicillin , only by the presence of an amino group .
Ampicillin is able to penetrate Gram - positive and some Gram - negative bacteria .