Ampicillin Trihydrate

Ampicillin, a penicillin-like antibiotic, is enzymatic synthesized from 6-APA [A0800] catalyzed by penicillin acylase. Ampicillin is the first of a number of so-called broad spectrum penicillins. That amino group helps the drug penetrate the outer membrane of Gram-negative bacteria. Thus, ampicillin has activity against not only Gram-positive bacteria such as Staphylococci and Streptococci but also Gram-negative bacteria such as H. influenzae, coliforms and Proteus species. It acts as a competitive inhibitor of the enzyme transpeptidase, which is needed by bacteria to make their cell walls. Its spectrum of activity is enhanced by co-administration of sulbactam [S0868], a drug that inhibits beta lactamase an enzyme produced by bacteria to inactivate ampicillin. Ampicillin is used in molecular biology as a selective reagent most commonly to isolate bacteria coupled to a gene coding for ampicillin resistance, which is one of the most frequently used selection markers for obtaining transgenic cells.