It’s been shown that there are 10 times as many bacteria on you as there are human cells in your body, this is called your microbiome. Your microbiome plays an important role in aiding digestion, training your immune system and preventing the growth of harmful bacteria. For the most part this bacteria does no harm to you, however every so often you get infected with pathogens that require the use of antibiotics. This video helps explain good vs. bad bacteria.
Antibiotics, like penicillin, kill bacteria by targeting the unique traits that make them bacteria, like their cell wall or specific enzymes. This means the drugs don’t affect human cells and can often be used with minimal side effects.
Antibiotics, in general, are very good at killing off bacteria and this is why they have been successful in limiting the impact of infectious diseases since their introduction around the 1940’s. The trouble is that bacteria are very good at adapting to their environment and sharing that adaptation with other bacteria. As such bacteria can evolve resistance to an antibiotic if it is over used or used improperly. How do they do this? If a handful of bacteria have an enzyme that can break down your antibiotic, these bacteria will survive and begin to reproduce. After a short time, all the bacteria will now be resistant to your antibiotic. Now, to treat that infection, you need stronger antibiotics and this gives the bacteria the chance to evolve resistance to another drug.
This arms race between bacteria and antibiotics is something researchers and doctors struggle with. Luckily new antibiotics are starting being discovered. You can help limit the rise of resistance by only using antibiotics when necessary and always using them correctly. That means getting rid of your antibiotic hand soap and cleaners.