Natural Penicillins
Agents: penicillin G, penicillin V
All of us have heard of the discovery of penicillin by Sir Alexander Fleming in 1929. Once penicillin was isolated years later, it had a major impact on society, particularly in the treatment of wound infections. The importance of this became apparent during World War II, when the Allies had access to penicillin and the Axis did not. Unfortunately, staphylococci quickly became resistant to penicillin, initiating the search for new beta-lactams and leading to the confusing array of these drugs available today. The development of resistance has narrowed the spectrum of effectiveness of natural penicillins considerably over the past 60 years, such that staphylococci are almost universally resistant to them. Occasionally we still see an isolate of Staphylococcus aureus that is susceptible to penicillin.
Spectrum
Good: Treponema pallidum, most streptococci Moderate: Streptococcus pneumoniae, enterococci Poor: almost everything else
Adverse Effects
Similar to adverse effects for other beta-lactams.