Antibiotics

Lina is not feeling well. She has a fever, sore throat, and tender lymph nodes in her neck. She went to see the doctor, who ran some tests and found that there are bacteria in Lina’s throat. The bacteria are causing an infection, which is making her ill. The doctor determined that Lina’s infection is severe and unlikely to clear up on its own.

She prescribed some medication to treat the bacterial infection — an antibiotic. How will the antibiotic cure Lina of her bacterial infection? First, let’s take a closer look at the bacteria that are causing Lina’s infection. All bacterial cells are surrounded by a cell wall. This wall grows together with the bacterial cell, and can be repaired if need be.

When the cell wall needs repairing, parts of it are assembled inside the cell. Then, those assembled parts are transported to and incorporated into the growing wall. The antibiotic that Lina’s doctor prescribed — penicillin — prevents that from happening. How? When penicillin is present, the bacterial cell wall can’t grow — because penicillin prevents it!

With no way of patching up the holes in the cell wall, the cell eventually has nothing holding its contents in, and dies. Antibiotics such as penicillin that kill bacterial cells are called bactericidal antibiotics. So penicillin destroys bacterial cells — does it attack Lina’s own cells too? No! Animal cells, including those of humans, don’t have a cell wall, so there is nothing for penicillin to attack.

Not all antibiotics work in the same way though. There is another group of antibiotics that doesn’t kill the cell. Instead, these antibiotics work by entering the bacterial cell. From there, they prevent the cell from producing the kind of molecules it needs to survive. They can also stop the cell from dividing and making more bacterial cells.

These antibiotics are called bacteriostatic antibiotics. Different types of antibiotics work on different types of bacterial cells. There are antibiotics that affect many different species of bacteria — we call these broad-spectrum antibiotics. Then, there are those that only work on a few select species of bacteria — narrow-spectrum antibiotics. The fact that not all antibiotics are equally effective against all bacteria, is one of the reasons why it was important for Lina’s doctor to run tests and see what exactly was causing Lina’s illness.

Another reason is that if Lina’s illness was not caused by bacteria, but by a virus, antibiotics wouldn’t work! Viruses don’t have a cell wall that antibiotics could attack, and they don’t multiply like bacteria either — so antibiotics are entirely ineffective against viruses. Finally, using antibiotics when it’s not necessary, or using the wrong type of antibiotic, can lead to the development of bacteria that aren’t affected by antibiotics — antibiotic resistance. The more bacteria are resistant to antibiotics, the more difficult it becomes to treat and cure bacterial infections. Researchers are continuously looking for new antibiotics and ways of treating diseases caused by bacteria.

There is also something you can do, Lina, to help prevent antibiotic resistance. You must take the antibiotics exactly as prescribed, at the right time of day and for as long as the doctor said, even if you start feeling better after a couple of days! By doing that, even the most persistent bacteria will clear up, and there will be no survivors that could stop antibiotics from working.