I understand a vaccine, a small dose of ‘x’ is given so your body can realise it’s foreign and learn how to fight it when the real thing comes.
But surely with a penicillin dose not being a vaccine,the body now has both it AND the foreign body to deal with? How does it’kill’ the intruder and not detrimental to the immune system?
Edit; Added words for clarification.
Edit 2; Thanks all, I have an understanding now!
In: 6
Penicillin isn’t a vaccine, it’s an antibiotic.
It kills bacteria in your body, then a few hours later you pee it out.
Penicillin works on a specific class of cells called Gram-positive cells. These are cells with a specific kind of cell wall. Penicillin works to inhibit the formation of this wall, making the cells die.
It turns out that a lot of common bacteria are Gram-positive. Human cells, on the other hand, are not. This makes penicillin effective at killing an infection but not your own cells.
Vaccine is a nerfed version of a virus, which is a living thing, or at least it has DNA, specialized components, and it tries to “talk” to body’s cells and pretend to be a legitimate part of the body. Immune system works by detecting this behavior. Virus is a bit like Impostor in Among Us.
Penicillin is an antibiotic, it is not living thing, but a much simpler chemical. It does not do anything as involved as a virus, it just tries to have a chemical reaction with anything it encounters. As it happens, that reaction works with bacteria and kills them, but it does not happen with human cells. So penicillin does the job of the immune system, but faster. (while the vaccine trains the immune system).
Immune system can decide that penicillin is a threat, i.e. patient gets a penicillin allergy. But it is rare, and even if it happens its symptoms are usually way more mild than bacteria infection that penicillin kills.
What others have said about penicillin directly disrupting the cell wall of bacteria is true. They don’t rely on the immune system to destroy bacteria.
As far as interactions with the immune system, people can become allergic to penicillin as they get sensitized to repeat doses. The most common such reaction is a rash, but penicillin allergies can escalate to even more dangerous reactions, including anaphylaxis.
There are three major types of antibiotics, penicillins, macrolides and fluoroquinolones are able to target differences between bacteria cells from human cells to fight infection. https://youtu.be/04brjRdc02w
[This is penicillin](https://image.shutterstock.com/image-vector/penicillin-chemical-formula-on-white-260nw-1485167528.jpg). It’s a chemical *produced by* the penicillium microorganism. When you take penicillin you are taking this chemical, **not ingesting the penicillium (mould) itself**.
Penicillin (the drug) only has a few dozen *atoms*. That’s thousands of times smaller than microorganisms. Your immune system doesn’t attack anything this size.
As someone else already said, your body deals with foreign chemicals (like penicillin) by filtering them out of your blood at the kidneys, which is what happens.
Vaccines are prevention, antibiotics are medication to help with an active infection (usually – they can be given preemptively if the dr’s concerned you might be about to develop a bacterial infection).
A vaccine primes your immune system to fight, making sure it has the antibodies to recognize and attack a particular invader the next time it sees one.
An antibiotic makes the battlefield actively hostile for the enemy when you’re already under attack.
It’s the difference between putting out an APB or putting up sandbags and barbed wire, vs providing close air support (or using mustard gas) during an active engagement.
The penicillin is a chemical weapon that actually gets in there and kills the pathogenic bacteria. More specifically, it inhibits a reaction that bacteria use to build their cell walls, so that bacteria exposed to it eventually break open and die. It has nothing to do with the immune system itself – the immune system doesn’t recognize penicillin or try to fight it, because the immune system is designed to recognize and attack foreign organisms, and penicillin isn’t one.
Bonus: antibiotics (including penicillin) pretty much only work against bacteria (and sometimes fungi). It’s why doctors don’t want to prescribe antibiotics for a cold or the flu (because those are viral). Viruses are best fought by priming the immune system (with a vaccine) to recognize and eliminate them itself, though we have developed numerous antiviral medications that can help, in some cases, like Tamiflu.
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