Antibiotics

Ugh. Your nose feels stopped up. You are coughing and sneezing. You swear the top of your head is going to pop off, if you sneeze one more time. Sounds like all the symptoms of a sinus infection. You finally cannot take it anymore, so off to the doctor you go to get some medicine. For a sinus infection, most likely you would be prescribed antibiotics. So what are these wonderful medicines and how do they work?

Bacteria are tiny single celled organisms. Most bacteria do not cause illness, but some can. If an illness-causing bacteria does get past your immune system and start reproducing, it can cause an illness. We want to kill these bacteria to eliminate the disease. Essentially, antibiotics are selective poisons used to kill bacterial cells.

Certain bacteria produce chemicals that damage or disable parts of our bodies. In a sinus infection, for example, bacteria have gotten into the sinuses. The body works hard to fight off the bacteria, which cause inflammation. The inflammation in your sinuses is what makes it feel like your head could pop off. The antibiotic kills the bacteria, which reduces the inflammation, and then you feel better.

Antibiotics work by either killing the bacteria completely, called bactericidal, or by disrupting the membrane of bacterial cells, called bacteriostatic. Antibiotics can also inhibit bacterial growth by keeping bacterial cells from making proteins and acids that they need for survival and reproduction. The overall goal of the antibiotic, which can be made from naturally occurring fungi or chemical compounds, is to harm bacterial cells without harming human cells.

In order to understand how antibiotics work, we need to explore the structure of bacterial cells. Bacterial cells differ significantly from most plant and animal cells. Proteins and DNA cells are targeted using antibiotics and only select bacteria for attack.

In medicine, verifying that a person has a bacterial infection prior to prescribing antibiotics is very important. Antibiotics only work on bacteria. They do not work on viruses, because a virus is not alive. A bacterium is a living, reproducing organism. A virus is essentially just a piece of genetic material. It injects its genetic material into a living cell, and then the infected cell reproduces more infected cells. With a virus, there is nothing to kill, so antibiotics do not work on them.

If you have been prescribed a course of antibiotics, finish the entire course--even if you feel better. When you do not finish the entire course, there may still be some bacteria that have survived, but are too low in numbers to cause symptoms. These remaining bacteria are the “fittest,” having survived this long. If you stop the antibiotics early, these “fit” bacteria are able to reproduce. This can cause antibiotic resistant bacteria, which require more specialized antibiotics that are more harmful to human cells.