Скачать или смотреть Vibrio Cholerae (Cholera) - Pathophysiology - Symptoms - Diagnosis - Treatment

Cholera is an intestinal infection caused by Vibrio cholerae. Vibrio cholerae organisms are comma-shaped, gram-negative bacteria which looks like little red or pink comma-shapes on a gram stain. And Vibrio Cholera is actively motile through a flagellum which it uses for movement through the gastrointestinal tract.

So how is cholera transmitted and what are the some of the risk factors ?
Cholera is caused by ingestion of contaminated water containing cells of Vibrio cholerae, it can also be contracted from contaminated food, especially improperly cooked shellfish.

Although Vibrio cholerae survive well in their aquatic environment, it is sensitive to stomach acids. So persons with impaired stomach acid secretion or who are taking antacids are at higher risk of infection. And another risk factor is blood group O patients. So individuals with a positive or negative O blood groups are more likely to infected with cholera.
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So how does vibrio cholera cause infection ?

We first ingest the bacteria it enters into the stomach it survives the gastric acidic environment and enters into the small intestine.And once it gets into the small intestine it starts to multiply in the intestinal mucosa.Then it starts to produce cholera toxin. This toxin binds to the plasma membrane of intestinal epithelial cells and releases an enzymatically active subunit that causes a rise in cyclic adenosine monophosphate or cAMP production. Resulting high intracellular cAMP level blocks the absorption of sodium and chloride by the microvilli and promotes the secretion of chloride, bicarbonate, potassium and water by the intestinal epithelial cells. The result is watery diarrhea containing masses of intestinal mucus and epithelial cells—called “rice water stools” from their appearance.

And this watery diarrhea causes dehydration and electrolyte loss.

While the incubation time for Vibrio cholerae can take hours, to 2-3 days; severe dehydration and depletion of electrolytes can happen within 4 to 12 hours of the first bout of diarrhea.
These imbalances can lead to symptoms like disorientation, dry mouth, swollen tongue, sunken eyes and cold clammy skin.
Other, even more severe, fatal complications can come from depleted electrolytes and water in the blood.
Like low levels of bicarbonate can cause metabolic acidosis with deep and labored breathing called Kussmaul breathing.
Or low levels of potassium can cause muscle dysfunction including leg cramps, weakness and abnormal heart rhythms.
And low chloride and sodium can cause headaches, poor balance, disorientation, seizures and coma.
Finally, severe dehydration can cause hypovolemic shock with a significant decrease in blood pressure.

So how we diagnose cholera ?
You can do stool cultures for vibrio cholera. And in some places where there are not good access to labs like some developing countries they have stool dipsticks to quickly check if someone has cholera or not.

The most important part of treatment consists of water and electrolyte replacement to correct the severe dehydration and salt depletion. Many antimicrobial agents are effective against Vibrio cholerae, but these play a secondary role in patient management. Oral tetracycline and doxycycline tend to reduce stool output in cholera and shorten the period of excretion of vibrios.