Antibiotic Resistance

A common belief is that you do not need to finish your course of antibiotics. Once you feel better you can stop taking them. This is not true! Not finishing your course of antibiotics puts you at risk of developing an antibiotic resistant strain of bacteria? How does that happen? Let’s take a look at bacteria, antibiotics, and bacterial evolution to see why this happens.


What are bacteria? Bacteria belong to a class of living things called Prokaryotes. The tree of life is divided into three main categories, Prokaryotes, Eukaryotes and Archaea. We belong to Eukrayotes, and another group of life forms belong to Archaea who often live in extreme conditions including high heat and without oxygen. Bacteria are all unicellular organisms that multiply quickly. Each time they create a new cell, those cells in turn can split into two more cells. This allows them to experience what is called exponential growth, meaning that the rate of their growth increases each time they reproduce.

Once bacteria manage to get inside our body they repoduce quickly. They cause damage to us in two main ways, through chemicals known as cytotoxins which damage our cells and cause tissue damage and death, and by provoking our body’s own immune response to cause inflamation which causes tissue damage.

Why do bacteria cause “diseases”? Why don’t they simply live their life quietly, living off one human. Whether or not you believe that humans came from single-celled organism, evolution in bacteria is both rapid and easily verifiable. Traits that make bacteria stronger and able to have more “kids” are favored and they win out in the long run because they produce more offspring. Sometimes your symptoms when you are sick the bacteria actually trying to spread their offspring to more people. A random mutation (a change in that bacteria’s DNA), caused a new symptom to appear when that bacteria infected a person. Once the new bacteria infected someone, it was able to spread its genes to more people and became a survived well enough to continue spreading.