To get accurate results from their studies of a single type of bacterium, microbiologists frequently work with pure cultures. However, if their job is not done under sterile conditions, other bacteria or even certain minute fungus residing in the environment may contaminate the tubes and plates. Most microbiologists start over and discard that culture if it occurs. But Sir Alexander was different from other microbiologists.
Fleming was returning from a vacation with his family early on September 3, 1928. Fleming was working with Staphylococcus aureus, a relatively prevalent pathogen, just before he left on vacation. Fleming left some glass Petri plates with these bacteria growing on the tops of solid media on his workbench. Typically, a lab worker would disinfect these plates before reusing them in other tests. Even if his experiments were left on the bench for weeks, Fleming always gave them one more review before throwing them away. He would draw samples at random from the stack of plates to check whether anything interesting had occurred during the previous several weeks.
Sir Alexander Fleming usually had contaminations on his plates since his
laboratory was relatively primitive; these contaminations were commonly brought
on by yeasts and molds from the environment. However, one plate showed out
different from the others, and when he observed it, he immediately said,
"That is funny. The plate was contaminated with a small fungus that produced
a large colony on the plate's side in addition to a thick culture of bacteria
when it was injected. It was strange that the fungal colony's closeness
inhibited the bacteria from growing there.
We now refer to this as a zone of inhibition, which is the region
around an antibiotic source where bacterial colonies do not grow. There was a
clearly visible area surrounding the fungus that was completely free of
bacteria. Fleming thus found that a fungus (Penicillium notatum) was producing
a substance that killed the potentially harmful bacterium Staphylococcus
aureus. Fleming had just found an antibiotic, which he initially referred to as
"mold juice."
Neither Sir Alexander Fleming nor his colleagues believed that this
finding could have any lasting value at the time; the importance was only
appreciated more than ten years later. Fleming had only just become aware of
the biological fight between different microbes fighting for available space in
nutrient-rich environments. Fleming did not discover penicillin; instead, he
noted that a colony of a minute fungus produced penicillin in an effort to
outcompete bacteria for nutrients on a plate that was about to be discarded.
Since then, microbiologists have successfully sought for new antibiotics in
nature to test whether any other microbes are capable of producing them.
In his receiving speech for the Nobel Prize in 1945, Sir Alexander Fleming also mentioned that bacteria may develop antibiotic resistance. Bacteria are able to adapt to any barrier inhibiting their growth very quickly, thus this is just a result of evolution. Random DNA mutations may be the cause of the change mutations in bacteria, and the process is extremely fast could practically see it happen in real time!
Most microbes that produce antibiotics also include genes that make them resistant to such drugs. In order to gain new capabilities, bacteria are very good at collecting DNA from other organisms. The term for this is horizontal gene transfer. A given antibiotic loses its clinical efficacy if pathogenic bacteria develop the genes essential to resist it. Antibiotics should only be utilized when required, at the proper dose, and for the full duration of the recommended course of treatment in order to ensure that all the bacteria causing the infection are eradicated. If we do not take these precautions, we may be contributing to the rise of antibiotic resistance, which is a serious issue. In fact, the most harmful bacterial infections are evolving antibiotic resistance.