Indications 1.respiratory tract infection 2.urinary tract infection .3.bone and joint infection 4.skin infection 5.soft tissue infection sdose:adult: 250 - 500mg every 6 hours for 7 - 10 days.mechanism of action of ampicillinampicillin is a bactericidal drug. it is a beta lactum antibiotic. it binds to the penicillin binding protein in the cell wall of bacteria and inhibits the enzyme transpeptidase which is responsible for the transpeptidation reaction in peptidoglycan synthesis. it also activates the endogenous enzyme which degrades the peptidoglycan.these results in inhibition of protein synthesis and there by cell wall synthesis. ampicillin is active against both gram positive and gram negative organism.