Ampicillin trihydrate is a semisynthetic penicillin derived from the basic penicillin nucleus, 6-aminopenicillanic acid.
It is used in the treatment of respiratory, GI, and GU tract and soft tissue infections, bacterial meningitis and enterococcal endocarditis, septicemia and gonococcal infections caused by susceptible microorganisms.
Reference: Complete ampicillin information. Internet. August 21, 2011. Available at http://www.drugs.com/ppa/ampicillin.html