Penicillin was one of the first commercially available antibiotics and is a still widely used class of antimicrobrial. The spectrum of action of these drugs is as follows:
1. Very little coverage for Staphylococcus
2. Very little coverage for gram negative bacteria
3. Good Streptococcus coverage
4. Good coverage for syphilis, Lyme disease, and Neiserria meningitidis
5. Can be used in anaerobic infections occurring in the thorax and more cephalad