Which antibiotic was not effective against e. coli? neomycin, penicillin, erythromycin, ampicillin

The antibiotic called ampicillin was not effective against E.coli.

D

Explanation:

E.coli is normal microbial flora which is present in the gut of the mammals.

It is gram negative bacteria and very few strains of this bacteria causes harm.

Antibiotics are the chemical drugs which are used to treat the microbial infection either by killing the causative organism or by its growth inhibition.

Antibiotics such as neomycin, penicillin and erythromycin are usually used to treat E.coli infection.

Antibiotic such as Ampicillin is not used as the bacterium E.coli is highly resistant to it.