Penicillin
Penicillin acts both by killing bacteria and by inhibiting their growth. It does not kill organisms in the resting stage but only those growing and reproducing. Penicillin is effective against a wide range of disease-bearing microorganisms, including pneumococci, streptococci , gonococci, meningococci, the clostridium that cause tetanus , and the syphilis spirochete. The drug has been successfully used to treat such deadly diseases as endocarditis , septicemia , gas gangrene , gonorrhea , and scarlet fever . SEMISYNTHETIC PENICILLIN Despite the effectiveness of penicillin in curing a wide range of diseases, infections caused by certain strains of staphylococci cannot be cured by the antibiotic because the organism produces an enzyme, penicillinase, capable of destroying the antibiotic. In addition, enterococci and other bacteria known to cause respiratory and urinary tract infections were found intrinsically resistant to the action of penicillin. Appropriate chemical treatment of a