About this video
The narrator explains how Salmonella enterica, usually picked up from contaminated or poorly stored food, survives stomach acid and invades the intestinal epithelium with flagella and injected compounds. Endotoxin triggers cytokines and cell death, which causes diarrhea, cramps, and vomiting, and treatment is mainly fluids with antibiotics reserved for severe cases.
You'll be able to
- explain how Salmonella reaches and invades the intestinal lining.
- connect the bacterial mechanism to the symptoms of salmonella poisoning.
- describe prevention and treatment for salmonella poisoning.
Key words
- Salmonella enterica
- The bacterium that causes salmonella poisoning, usually from contaminated or improperly stored food.
- Flagella
- Tail-like structures that let bacteria swim toward host cells.
- Endotoxin
- A molecule associated with the bacterial cell wall that triggers the release of cytokines in the host.
- Apoptosis
- Programmed cell death, which here kills the intestinal epithelial cells.
- Epithelium
- The layer of intestinal cells that digests and absorbs food.
Transcript
- [Voiceover] Salmonella poisoning is caused by a bacteria known as Salmonella enterica. It's usually contracted when people just eat plain old bad food. So I don't mean food that doesn't taste very good. I mean food that hasn't been cooked properly or hasn't been stored properly or has been contaminated with something containing the bacteria itself.
Now, when you eat this kind of food, the bacteria will enter your stomach. Remember that the stomach has a very acidic environment. As a result, most of the bacteria will die off. However, some may end up surviving and make their way into the small intestine. So why don't we look a little bit more closely at the small intestine itself.
Once again, there are many different layers of the wall of the small intestine. And we'll be focusing on this green layer known as the epithelium. The epithelium contains all of these cells that will be doing the digesting and absorbing. And it's these cells that the bacteria will invade.
So we can actually zoom in on one of the cells over here. Once again, this is our epithelial cell. And we have the bacteria over here. Now, this bacteria is pretty interesting because it actually has a whole bunch of different structures that look like tails. These tails are known as flagella.
Flagella is really just plural for flagellum. These bacteria will use this flagella to move it near the epithelial cell. At this point it then physically attaches to the epithelial cell and then injects a whole bunch of compounds into that cell. Those compounds will ultimately allow for the internalization of that bacteria.
So in other words, that bacteria will then be able to make this epithelial cell its new home. Now, remember that a lot of bacteria have this structure around them called the cell wall. And associated with that cell wall in this case is a chemical called an endotoxin.
That endotoxin will trigger the release of chemicals called cytokines. And these cytokines will ultimately lead to a process known as apoptosis, which just basically means cell death. So eventually this epithelial cell will die off. And now you have all of these cells in the epithelium just dying.
And remember that these cells are responsible for digesting and absorbing food. So now you can't do that anymore. As a result, you may experience a lot of different symptoms. Now, a like all of the forms of gastroenteritis or food poisoning, people will experience some diarrhea.
And given that this is a bacterial infection, people will experience bloody diarrhea. Vomiting and nausea is also common. And because you're constantly expelling the contents in your system, this can lead to dehydration. And finally, because you can't really absorb water as well, people may experience cramps.
Now, these are symptoms that you may see if the bacteria stays in the gut. You may actually see some other symptoms if the bacteria manages to enter the bloodstream. So for example, you may have a fever. This is typically uncommon, but it's possible for it to happen.
And if the person has a condition known as sickle cell anemia, then there's a good chance that the bacteria could cause a condition known as ostemyelitis. And this is really just infection of your bones. Now, typically, the symptoms start about one to three days after exposure.
And they'll usually last for about one week. Now, if you want to be safe, you can go to the doctor to get a real diagnosis. And like always, what they'll do is they'll take a stool sample. They'll then evaluate the contents of the stool sample and they'll see if it has the bacteria in it.
If it does, then you have Salmonella poisoning. If they decide that you have Salmonella poisoning, the doctor will most likely advise you to drink a lot of fluids. And in some cases they may even give you some antibiotics. Usually antibiotics will be given if the situation is pretty extreme or severe.
And as always, the best way to prevent getting Salmonella poisoning is by eating clean food and drinking clean water.
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