ELI5, if Stomach acid kills bactaria we ingest, how do we still get food poisoning like samonella?

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ELI5, if Stomach acid kills bactaria we ingest, how do we still get food poisoning like samonella?

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It can actually alter its own ph to adapt and live in the high acid environment of the stomach.

Your question is factually incorrect, stomach acid does not kill all bacteria.

There are other issues as well. Sometimes we get ill because toxins have already been released in contaminated food, killing the bacteria does not remove the toxins.

There is actually two different types of foodborne disease, infection, and intoxication or poisoning.

On the case of infection, the bacteria has evolved over time to be able to survive the harsh environment of the stomach and make it to the intestines, where it can colonize and grow. E. Coli O157:H7 is a bacteria that makes you sick in this manner.

For intoxication, the bacteria have actually grown in the food and created a poison before you ever eat the food. The toxin produced is extremely hard to remove or degrade to where it is no longer harmful. One of the major concerns in canned food, clostridium botulinum, causes illness like this. Your stomach will kill the bacteria itself, but it won’t have any effect on the toxin or spores if they have already been produced.

First, many bacteria are resistant to stomach acid.

Second, some food poisoning is not caused by the bacteria themselves, but by toxins they produce. So even if the cooking process/ stomach acid kills the bacteria, the remaining toxins can make you sick.

In the case of different types of salmonellas which are sensitive to gastric acid, you just need a a ton of them… a large enough load for some of them to survive the journey, and if enough make it boom infection (maybe).
They then use whatever characteristics they have to their advantage. Perhaps one bacteria is motile and can get to places easily. Perhaps the have a special viral antigen that ends up blocking or interfering with regular antibodies.
There are a lot of cases in biology where all you really need for any one thing to do something is to put a lot of it somewhere haha.