So I know if you take antibiotics, and you stop once you feel better, can cause the infections to come back even worse and you might possibly develop a antibiotic resistance but what’s the difference between that and finishing your medication? For example, my antibiotics I take 2 a day for 7 days. How does finishing my medication not cause a resistance?
In: Biology
Think of your infection as a medieval army. The army is made up of a bunch of different people with different ethnicities, nationalities, and genetics, but most of them have swords.
However, you have a special weapon: a cannon. A cannon can wreak havoc on an army that’s not prepared. So most of the enemy is dead very fast because they don’t know cannon warfare. But some segments of that army are trained in cannon warfare, so they aren’t as weak to your cannon tactics.
However, if you blast the small cannon-trained segment that remains, day after day after day with the same cannons, they’ll still dwindle in numbers.
Even those who know cannon techniques will still die every day, and after a while (your prescription period), there’s not enough of them to stand up to your cannons even though they know how cannons work.
That’s how antibiotics work. There’s always some that are resistant, but you want to take out the army so much that even if they’re resistant to your cannons, they can’t possibly win a battle with 1,000 of their own vs. 1,000,000 of your own immune cells.
Taking your antibiotics for 1-2 weeks makes sure that there’s very few left that know cannon warfare, and your immune system can just sweep them away.
If you stop early, its fairly likely some of the bacteria will survive the treatment. Those that do are going to be those already resistant to the antibiotics you were prescribed. Basically, taking antibiotics creates a strong evolutionary pressure towards antibiotic resistance as those traits are required for the bacteria to survive.
If you take all of your medication, its very likely all of the bacteria will be killed off between the antibiotics and your immune system, thus leaving nothing to evolve a resistance. The treatment regime is generally tuned to ensure an extremely low survival rate for the disease.
Imagine you are super man and the sun heals you. You are weak and injured fighting a foe. You healed a little in the sun but went to fight before you were ready. The foe as time progressed got smarter and stronger and now takes more energy or help to defeat him.
If you finish the course all bacteria will be dead either by antibiotics or your immune system finishing them off.
If you don’t finish the course, some bacteria may survive and multiply again more than the immune system can handle. But now the bacteria are the ones descended from those that survived antibiotics treatment better than general bacteria population. Basically you made an artificial selection of bacteria resistant to that antibiotic and let them multiply afterward.
It’s not going to happen every time someone drops antibiotics early, but it may happen.
The longer bacteria are exposed to antibiotics the more chance they have to evolve resistance.
According to Harvard Health blog
“There is no evidence that longer courses prevent the development of antibiotic resistance. In fact, just the opposite may be true.”
It is common wisdom that finishing course of antibiotics is vitally important, but this would depend entirely on the specific interactions of bacteria, with drug, dosage and length and the complexity would be beyond the expertise of prescribing doctors.
When you first start taking antibiotics, usually the first round of it wipes out the majority of the bacteria that are damaging your tissue. Because most are gone, you feel relief. However not all of them are gone immediately, a few stragglers that may be a little more resistant are still alive, not enough for you to notice, but still present.
A prescribed course of antibiotics is designed to intentionally be overkill to ensure every last bacteria is obliterated. If you stop early and a few of those survive, the infection can rebound as those survivors multiply. Whats worse, since those survivors lived longer because they had traits that made them more resistant, as they copy themselves and multiply, all of the bacteria in the renewed infection will now have these traits, with a few possibly having developed an even stronger resistance through random mutations, and now instead of most of the infection being eliminated on the first round, most of them might survive that first round and the whole infection will now take longer to get rid of, or the antibiotic may stop being effective entirely.
Its in a way artificial selection. By stopping early, you have effectively cleared the way for only the toughest and most resilient bacteria to repopulate and potentially become even stronger.
People also discourage using antibiotics when you don’t have an illness that needs them because this resistance can be developed in bacteria that are normally harmless or easily defeated in or on your body, and in some cases two different species of bacteria can actually exchange genetic information, so a resistance can sometimes spread between multiple species of bacteria.
The resistance isn’t in you, it is in the bacteria. As others have said the bacteria mutate.
Antibiotic resistance is not an individual phenomenon. It’s a societal phenomenon. The same bacteria cannot be resistant to antibiotics in your body, while responding to them in mine. You might use antibiotics correctly, but if everyone around you abuses them, you are as susceptible to these resistant bacteria as everyone else.
When you take antibiotics the weaker bacteria get killed first, while the stronger survive. The stronger ones get to proliferate as they don’t have to compete for resources with the weaker ones. That’s why there is a risk of infections rebounding even stronger. To avoid that the doctor might have asked you to take a full course of antibiotics, so that the stronger ones are also killed.
However in many cases, your immune system is perfectly capable of handling the bacteria, it’s just overwhelmed with the quantity of them. In those infections, a high powered single or couple dosage of antibiotics is recommended. In fact you might not want to be on antibiotics for a longer period, because unless the antibiotic is extremely specific, it also wreaks havoc on all the beneficial bacteria elsewhere in your body.
Antibiotic resistance though is far more complex. It happens when people as a whole overuse antibiotics, spread the stronger surviving bacteria among one another, and the bacteria under constant pressure of antibiotics evolve over multiple generations to develop a resistance to the antibiotics. Then it’s a constant race between developing new antibiotics and the ever evolving bacteria.
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