Infection and Disease Host Microbe Relationships o Mutualism o Commensalism o Parasitism Mutualism When both species directly benefit o Ex Animals provide home for intestinal microbes and microbes give off Vitamin K to animal Commensalism When one species benefits and the other is neither benefitted nor harmed o Ex Dental plaque benefits from living and reproducing in our mouths but we do not benefit from dental plaque Parasitism When one species benefits while the other is harmed o Ex Parasite worms eating away at flesh and blood of animals Normal Indigenous Microflora o Mutualistic or commensal microbes living on the surface of human body o Body systems closest to the outside of the body have more microbes than the internal body systems o The deeper you go into the body the less microbes you find or may even be sterile 1 Resident Microflora Always present on body surfaces from child 2 Transient Microflora Only present under certain conditions that birth to end of life span can last a few months to a year Look at table 13 3 in textbook Flora and examples of each Compare habitats and see how they are different 1 Skin 2 Gastrointestinal Tract oral cavity 3 Large Intestine Rectum Harmless Microbes Become Harmful Pathogens When o Numbers increase more than normal o Microbe enter sterile areas of the body Ex When microflora enter the sterile bladder and form UTI urinary tract infection Canidida Albicanst form of yeast that can cause Vaginitis or Thrush Disease of oral cavity in infants causing white layer of yeast to grow in mouth Clostridium Difficile C Diff Causes overgrowth to occur in the GI tract Antibiotics alter environment of colon o Immunocompromised Failure of immune system Disease can come from your own microflora or sources external to the body Modes of Transmission o Contact o Vehicle o Vector Contact Transmission Physical Contact o Spread from ill human to human contact o Examples STDs or venereal disease Ex gonorrhea genital herpes AIDS HPV Direct fecal oral intestinal infections passed along Ex Day care centers Vertical Transmission Passed from woman to unborn child or child during birth Indirect Contact Transmission Colds coughs sneezes Fomites non living objects No direct contact Ex toys children share
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