Escherichia Coli (ETEC)

by Vincent Racaniello, PhD

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    00:00 So the first strain we'll talk about, and there are several, is called Enterotoxigenic E. coli or ETEC. There are lots of abbreviations we're going to be hitting here, we'll show you a table at the end so you can remember them all. ETEC causes traveler's diarrhea. Why does it cause that? You go to another country, within a day or two, you get diarrhea, watery diarrhea after you've eaten some local food. That's traveler's diarrhea. It's annoying, but it happens. It affects children and adults all over the world; you've probably heard of it, it's caused by ETEC strains of E. coli. These use fimbrial or pili adhesins to bind two enterocytes in the small intestine, very much like the vibrio that we've talked about and these strains, the ETEC strains, make two enterotoxins. An enterotoxin is simply a toxin produced by the bacteria that affects your enteric tract. The ETEC strains of E. coli produce an LT enterotoxin, this is very much like a cholera toxin, it gets into the cell, causes increased amounts of cyclic AMP. Now what does it do to sodium levels? Pumps it into the cell, pumps out chloride. There you go, you get your watery diarrhea, as the cell then pumps out water to try and compensate, LT enterotoxin. The other toxin is called ST. This causes cyclic GMP accumulation in cells which also results in secretion of fluid and electrolytes, contributing to the watery diarrhea. So two enterotoxins, both of their effect is to cause an imbalance in the ion makeup of the cell and the cell excretes water and you get watery diarrhea. ETEC E. coli, two enterotoxins.

    01:47 These bacteria are not invasive, they sit on the surface of your epithelial cells in your gut, they attach to the gut surface by the pili and they sit there, make toxins and you have diarrhea, they don't go in, they're not invasive. So an important distinction, these are simply bacteria, very much like the cholera, vibrio cholera, sits on the surface, they do not invade.

    About the Lecture

    The lecture Escherichia Coli (ETEC) by Vincent Racaniello, PhD is from the course Bacteria.

    Included Quiz Questions

    1. ETEC
    2. EHEC
    3. V. cholera
    4. EPEC
    5. EAggEC
    1. Activates adenylate cyclase to increase cAMP concentrations
    2. Inhibits the 60s subunit of ribosomes
    3. Increases levels of cGMP into the intestine
    4. Decreases Cl absorption, increases Na secretion
    5. Decreases secretion of fluids and electrolytes, leading to cell lysis
    1. ST toxin — increased cGMP; LT toxin — increased cAMP
    2. ST toxin — increased cAMP; LT toxin — increased cGMP
    3. ST toxin — decreased cGMP; LT toxin — increased cAMP
    4. ST toxin — increased cGMP; LT toxin — decreased cAMP
    5. ST toxin — decreased cAMP; LT toxin — decreased cGMP

    Author of lecture Escherichia Coli (ETEC)

     Vincent Racaniello, PhD

    Vincent Racaniello, PhD

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    best review for microbiology
    By Mohammed A. on 06. December 2018 for Escherichia Coli (ETEC)

    great lecture ,great professor! all the lectures are very much cover all the important concepts . just need more videos to cover the other bacteria like klebsiella,spirochetes,syphilis and the zoonotic bacteria .