Gram + bacterial microbiota - Yin & Yang of infectious disease

Published on September 27, 2011 Updated on January 31, 2017   55 min

Other Talks in the Series: Microbiota

0:00
Welcome to another lecture on this series on the human microbiome. I'm Pat Cleary. I'm a Professor of Microbiology at the University of Minnesota. I've spent many years working on the pathogenesis of group A Streptococcus. You'll notice in my title that I have a subtitle "Yin & Yang of Infectious Disease". This is a special interest of mine because there are many bacteria which are members of the microflora, cause no problems at the time, but have the potential to also cause very serious infections and are considered primary pathogens. Those same pathogens can also revert back to being normal flora.
0:44
As I'm sure you've learned already from some of the other lectures, our bodies are gardens of microorganisms. Some see the sun, they're on our skin. Some line the dark passages, such as our intestines. While others are just transient visitors.
1:00
During this presentation, I'll touch on several different genera of bacteria that can be either normal flora or primary pathogens. I'll spend a considerable time on Streptococcus, Streptococcus pyogenes, agalactiae, and pneumoniae. I'll touch on Staph aureus, and Clostridium difficile. I'll talk some about bifidobacterium, as a helpful member of the normal flora. And I'll mention Enterococcus as a source of antibiotic resistance.
1:36
The next three slides will give you a taste of what the microflora is on different parts of the body. Again though, I will tend to focus on Gram positive bacteria. And we'll start with the outer surface, the skin, which in fact is primarily Gram positive and can contain anywhere from 1,000 to 10,000 bacteria per centimeter. Staph aureus is common and Staphylococcus epidermidis. Corynebacteria are there, they're not pathogenic. The hair follicles are quite interesting actually, because they have their own microflora. The Gram positive bacterium, Propionibacterium acnes is one example. And as some of you know, when you reach puberty, the number of these bacteria increase because of the chemical changes in the sebaceous secretions, and pimples result, the bane of being a teenager. Blood, spinal fluid, and tissue spaces are sterile.
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Gram + bacterial microbiota - Yin & Yang of infectious disease

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