We are immersed in a vast sea of tiny organisms, microbes, most of which are either helpful or neutral. There are a few bad actors that can harm people and are responsible for plagues of the past, such as the black death, cholera and influenza epidemics.
This whole picture changed in the late 30s with the advent of Sulfonamides, and especially Penicillin, the “magic bullet”. I was practicing medicine early in the days when antibiotics eliminated almost all infections.
In fact, at one time infections were thought to be a problem of the past. Unfortunately, overusage, chronic multiple infections, surgically implanted devices, immune suppression for cancer and autoimmune diseases have allowed bacteria, fungi and viruses to evolve resistance mechanisms.
At the present time there are a number of bacteria, such as staphylococci, actino bacteria, enterococci, and candida that are essentially untreatable. Even if they are somewhat treatable, second and third level antibiotics are so toxic that they can cause problems with the kidney, liver, or heart.
In later postings, I plan to consider specific organisms and the situations in which they operate. I will also eventually talk about efforts to create new antibiotics by harvesting genetic material from unusual places, even our oceans.