#808 Do antibiotics kill all of the bacteria in the body?

Do antibiotics kill all of the bacteria in the body? Yes, they do.

Antibiotics kill bacteria in the body. They do not work on viruses. We use bacteria when we have an infection and they can be very effective. An infection is caused when we have a wound and bacteria get inside. This is very common because it is very difficult to keep a wound completely sterile and there are bacteria everywhere, including in the air. Once bacteria get into a wound, they start to multiply. They multiply by dividing themselves in half, each half becoming a new bacterium. A single bacteria can become 50,000 in the space of eight hours. Some bacteria produce toxins. Once the number of bacteria has built up high enough for the body to notice, it triggers an immune response. Blood flow to the area increases, causing swelling, and white blood cells are sent in to kill the bacteria. Antibodies are attached to the bacteria so they can be targeted, and the immune system is able to deactivate some of the toxins.

Our body can fight off a lot of bacterial infections and keep us safe. However, there are some infections that our bodies can’t fight off. These bacteria are able to avoid the immune system or they release exceptionally harmful toxins. The botulism toxin is the most dangerous toxin a bacteria can release, and only animals like vultures and hyenas can survive it. There is also a response to bacteria called sepsis that can kill people. Sometimes, bacteria enter the body and set up a colony. The immune system arrives to fight them off but, for reasons that are not completely understood, the immune system thinks that bacteria are all over the body and starts to attack everywhere at the same time. This leads to swelling over the whole body and ultimately organ failure through lack of oxygen. This can be potentially fatal.

Antibiotics were discovered in the 1920s and before their widespread use, about 30% of all deaths were caused by bacterial infections. During the American Civil War, more people died of infection than were killed in battles. 660,000 people died and about 440,000 of those were from infections. It was situations in wars like this that led Florence Nightingale to fight for better sanitation in war hospitals. She didn’t know what bacteria were, but she knew that wounded soldiers in clean environments lived longer than wounded soldiers in dirty environments.

So, how do bacteria work? There are different kinds of bacteria and there are different kinds of antibiotics. Some antibiotics target a specific bacterium and some are broad spectrum. Generally antibiotics stop or kill bacteria in three ways. Firstly, they attack the cell wall of the cytoplasmic membrane. If this is ruptured, the contents of the bacteria spill out and it dies. Secondly, they can stop the bacteria from reproducing. Thirdly, they can stop the bacteria from producing proteins, thereby making them ineffective. Once you start taking antibiotics they begin to kill bacteria straight away, but it might take a few days to get rid of all of them. People are told to complete a course of antibiotics because if you stop partway through, there might be some bacteria left, which will multiply again, reigniting the infection.

There are two problems with antibiotics. The first is that antibiotic resistance is increasing. We are using more antibiotics year by year and more bacteria have a gene that resists them. Ironically, by using antibiotics, we are helping the bacteria to become stronger because we kill off the ones that don’t have the resistance gene and leave the ones that do. We give huge amounts of antibiotics to industrial farmed animals as well.

The second problem is that the antibiotics kill the bacteria that cause the infection, but also the bacteria that we need to survive. The bacteria in the infection are “bad” bacteria, but we have 39 trillion bacteria that live inside us. Without these bacteria, we would not survive. We inherit them from our mothers when we are breastfed, and they increase and are added to through our lives. The ones that live in our guts help us to break down food, they control the storage of fat, they help activate the genes that absorb nutrients, they break down toxins, they help build blood vessels, they help replenish the lining of the intestine, they remove dead cells, they stop other bacteria from invading us, and many other things. Without them, we die. And antibiotics kill huge numbers of them. When you take antibiotics, you might find you get stomach aches, constipation, and other side effects. A lot of these are caused because we kill the bacteria we need. However, it is not the end of the world. We obviously have to choose wisely when we do and do not take antibiotics, but, once we have taken them, we can replenish the bacteria. We can eat yoghurt, kefir, and other fermented foods with bacteria in them. We should also eat foods with a lot of fiber because this can give the bacteria somewhere to grow on and can act in their place until they are restored. And this is what I learned today.

Photo by Pietro Jeng: https://www.pexels.com/photo/depth-photography-of-blue-and-white-medication-pill-360622/

Sources

https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/infections-bacterial-and-viral

https://www.healthline.com/health/how-do-antibiotics-work

https://learn.genetics.utah.edu/content/microbiome/antibiotics

https://www.bbc.com/future/article/20230825-do-antibiotics-really-wipe-out-your-gut-bacteria

https://pubmed.ncbi.nlm.nih.gov/8513069/