Written by: Timothy Sonniah

The use, overuse, and abuse of antibiotics are accredited with creating antibiotic-resistant strains of bacteria. How does this relate to natural selection?

When antibiotics are used for too long or abused by patients, the body responds by coming up with bacteria resistant to these antibiotics; this is directly related to natural selection as bacteria are quite many in the ecosystem. The process of mutation in bacteria, which in most cases is random, leads to alteration of the genetic composition of the bacteria depending on changes in the environment.

Similarly, after long term exposure to antibiotics, the bacteria’s genetic makeup gradually changes; it mutates and acquires coping mechanisms against the antibiotics present in the body; that is, the bacteria develop resistance to antibiotics. For instance, there is a type of bacteria that produces a “pump,” which is biochemical after long term exposure to antibiotics.

The purpose of the pup is to detect any medicines in the system and flush them as soon as possible; this is a resistance mechanism that the bacterial develops to survive in the ecosystem, which is the host’s body. Other bacteria have developed a tool whereby they secret particular enzymes; these enzymes are responsible for inactivating antibiotics in the body and thus rendering them harmless.

Whenever someone introduces an antibiotic in the system, it destroys the vulnerable bacteria. However, the other types of bacteria that are not susceptible to antibiotics pass the resistant trait to the future generation. Zaffiri, Gardner, & Toledo-Pereyra (2012) define resistance as a scenario whereby a particular type of medicine meant to serve as a curative for a disease is no longer active due to the change in the DNA makeup of the bacteria.

Human actions are significant causes of the resistance to antibiotics by bacteria. For instance, in healthcare setups, doctors and other health professionals tend to prescribe antibiotics to treat significant problems for minor issues. Thus when used for a long time, the patients’ bodies develop resistance to them and thus rendering them ineffective. In other sectors such as farming, farmers provide antibiotics to animals intending to alter or improve certain traits in the future offsprings; this is tampering or contributing to natural selection.


Zaffiri, L., Gardner, J., & Toledo-Pereyra, L. H. (2012). History of antibiotics. From salvarsan to cephalosporins. Journal of Investigative Surgery, 25(2), 67-77