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Infection Basics

by Vincent Racaniello, PhD
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    00:01 change your microbiome. And the consequences of the microbiome for human health are going to be learned in the next 10 years and we’re really going to find out fabulous ways that we can improve our health by manipulating it.

    00:12 Okay, onto infection basics. Let's talk about some principles by which bacteria can enter the host. We can divide bacterial infections into two broad groups depending on how they're acquired. Some are acquired exogenously, from some external source, like bacteria in the environment or bacteria in the food, the water, the air, the objects we touch, insect bites, or any animals, dog bites for example. And so those are exogenously acquired from elsewhere, and that contrasts with endogenously acquired infections, where our microbiome suddenly turns on us and this could be because we've altered the microbiome by treatments with antibiotics, and Clostridial infections of the intestine are a great example of that, where we alter the composition of this family of microbes and then suddenly clostridia overgrow and cause us problems. Sometimes injuries introduce skin bacteria into us, and this is commonly occurring with Staphylococci, normal inhabitants of the skin, when an injury introduces them below the skin, this can cause a problem. So we get bacteria that cause infections and illness from external sources and from within ourselves.

    01:35 Let's talk a bit about how bacteria gain entry to the host, the exogenous sources of infection.

    01:43 Here is a human body, which provides a very large spectrum of places for bacteria to enter, a very common place is a mucous membrane. We have mucous membranes all throughout our body, our eyes, our mouth and nose, the entire alimentary tract, which is essentially a very long tube starting from our mouth going through our intestines and out the anus, that is all lined with mucous membranes because it has to absorb food and excrete waste, and because it's a mucous membrane, it is vulnerable, it is not sealed against entry. Things like breathing, eating, having sex, all can introduce pathogens into us. Cholera, whooping cough and gonorrhea are example of bacterial infections that are acquired across mucosal membranes. Now we are happened to be covered by a wonderful protective organ called the skin. Skin is the biggest organ in your body, it weights the most, and it has the most square area and it is a great barrier. The outer layer of your skin is dead, so viruses cannot multiply in them, they have to get inside by penetration, but there are ways that the skin can be breached, allowing bacteria to invade the underlying cells and tissues. How can this happen? Insect bites of course, they routinely deliver things below the skin, any kind of scratch or injury, which we are all prone to having, will also breach that wonderful protective barrier. Once you're in a mucosal membrane, there are ways to get across that,


    About the Lecture

    The lecture Infection Basics by Vincent Racaniello, PhD is from the course Bacteria.


    Included Quiz Questions

    1. It is a part of the normal skin microbiome.
    2. It is a common exogenous pathogen.
    3. It alters the microbiome, making us more susceptible to infection.
    4. It is introduced via insect bites.
    5. The microbiome cannot protect against it.
    1. Mucus membranes
    2. Insect bites
    3. Open wounds
    4. Skin breakdown
    5. Tissue penetration

    Author of lecture Infection Basics

     Vincent Racaniello, PhD

    Vincent Racaniello, PhD


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