Does penicillin inhibit e. coli bacterial growth?

Most do.: Although there are e. Coli that are resistant to all penicillin-type antimicrobials, these exist mostly in hospitals. Without the antimicrobial pressure in the health care setting, most e. Coli are quite sensitive to most penicillins even ampicillin. Even though penicillin itself is not very useful for e. Coli, really high doses in the "old days" worked.