Escherichia Coli (EAggEC) and Invasive Enteric Bacteria (Bloody Diarrhea & Dysentery)

by Vincent Racaniello, PhD

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    00:01 The next strain that we would like to talk about are called enteroaggregative E. coli or EAggEC. These are strains only found in people, and I mention this because these are frequently seen in AIDS patients, so these kinds of diarrheal diseases are associated with immunosuppression.

    00:23 Enteroaggregative E. coli have fimbriae as you can see in this picture, which aggregate cells in culture and that's why they're called enteroaggregative strains. They bind to the intestinal mucosa, they cause watery diarrhea without fever, they are non-invasive, as are the other strains, they do produce a number of toxins, one of them is a hemolysin, and they produce an ST enterotoxin similar to that of the ETEC strains. The ST enterotoxins cause increase in cellular cyclic GMP, and this results in ion imbalances leading to watery diarrhea. Okay so those bacteria, the vibrio and the various strains of E. coli cause watery non-invasive diarrhea. Let's now turn to enteric bacteria that are invasive, they go beyond the surface of the epithelial cells, they invade the submucosal and they become systemic and they also cause bloody diarrhea, which is also known as dysentery. So when you have blood in your diarrhea, it's no longer watery diarrhea, it is dysentery. The intestinal pathogens that do this structurally damage the large intestine and they invade the mucosa, and that damage and invasion leads to bloody diarrhea or dysentery. So bloody diarrhea or dysentery, 30 passages a day, not as much as cholera, but 30 a day is still a lot. So it is stools with blood, mucus and pus in them, that's the definition of dysentery. These are life threatening infections, they require treatment with antibiotics, it's not sufficient to provide water rehydration, because here the bacteria are in your bloodstream and you can have all the water in the world, you're not going to get rid of those bacteria unless you take antibiotics, so they need serious treatment. Now we're going to talk about two different genres of bacteria that cause bloody diarrhea and dysentery. First the Shigella, shown on the left here and again we're back to E. coli, but these are again different strains of E. coli that cause invasive diarrhea. So you see E. coli can be very different depending on what genes it has, the first is the enterohemorrhagic or EHEC strains of E. coli and the second, the enteroinvasive strains or EIEC strains of E. coli.

    About the Lecture

    The lecture Escherichia Coli (EAggEC) and Invasive Enteric Bacteria (Bloody Diarrhea & Dysentery) by Vincent Racaniello, PhD is from the course Bacteria.

    Included Quiz Questions

    1. EAEC
    2. EHEC
    3. ETEC
    4. EPEC
    5. EIEC
    1. Increases cGMP in the enterocyte
    2. Acts like ETEC LT toxin
    3. Increases cAMP in the enterocyte
    4. Acts like cholera toxin
    5. Acts like Shiga toxin
    1. Invasion into enterocytes with damage to mucosa
    2. Bacterial pili adhesion
    3. Production of enterotoxins
    4. Biofilm formation
    5. Stimulation of angiogenesis

    Author of lecture Escherichia Coli (EAggEC) and Invasive Enteric Bacteria (Bloody Diarrhea & Dysentery)

     Vincent Racaniello, PhD

    Vincent Racaniello, PhD

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