Beta lactam antibiotics are normally bactericidal and require that cells be actively growing in order to exert their toxicity. Natural penicillins, such as Penicillin G or Penicillin V, are produced by fermentation of Penicillium chrysogenum. They are effective against streptococcus, gonococcus and staphylococcus, except where resistance has developed. They are considered narrow spectrum since they are not effective against Gram-negative rods. Semisynthetic penicillins first appeared in 1959.
Clavulanic acid is a chemical sometimes added to a semisynthetic penicillin preparation.
Thus, amoxycillin plus clavulanate is clavamox or augmentin. The clavulanate is not an antimicrobial agent. It inhibits beta lactamase enzymes and has given extended life to penicillinase-sensitive beta lactams. Although nontoxic, penicillins occasionally cause death when administered to persons who are allergic to them. In the U.S. there are 300 - 500 deaths annually due to penicillin allergy.