326Mintro-zoonoses - Microbiology Overview Microbes are...

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Microbiology Overview Microbes are categorized as: Bacteria (singular bacterium )- include spirochetes (Treponema), Rickettsia, Chlamydia, Mycoplasma Shigella, Pseudomonas, Streptococcus, Staphylococcus Fungi- yeasts ( Candida, Cryptococcus ) and molds ( Histoplasma, Aspergillus ) Viruses- polio, herpes, hepatitis, HIV, influenza, West Nile; Corona (SARS) Protozoa- Giardia, Toxoplasma, Cryptosporidium, Plasmodium Helminths- tapeworms, hookworms (eggs are microscopic) Prions- pr oteinaceous in fectious particles- aberrant self-replicating proteins
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Introduction to Host Parasite Relationships A. Symbiosis is two or more organisms living together, in close association. Ectosymbiosis- organisms remain outside each other. Endosymbiosis- one organism is present inside the other 1. Commensalism- “eating at the same table”. One benefits and the other is not harmed. E.g. Escherichia coli in bowel- benefits from host nutrients and environment 2. Mutualism- each organism receives some reciprocal benefit. Metabolic dependence on each other a. Protozoan-termite: flagellated protozoa digest the cellulose in wood chips, termites utilize the products and allow for growth of the protozoa b. Lichens: association of fungus (ascomycete) and either green algae or cyanobacteria. These symbiotes actually have scientific names. The alga/cyanobacterium (via photosynthesis) provides the fungus with O 2 and carbon. The fungus provides the alga from excessive light, and provides water, minerals and a stratum (base) c. Marine invertebrates such as jellyfish, sea anemones, corals harbor algae d. Tube worms in deep ocean rift vents are colonized by chemosynthetic bacteria which produce nutrients; worms provide shelter e. Ruminants and rumen microbiota- similar to the termite situation, but the endosymbionts are mainly bacteria which digest the cellulose. Ruminants provide food and protection for the microbiota
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Pathogenicity Infection ---------> damage to host-------------->infectious (Colonization) disease Etiologic(al) agent: microbe responsible for the Infectious disease; microbes can be bacteria, fungi, viruses, protozoa Pathogenicity is the microbe's ability to cause infectious disease Microbe's pathogenic <---------------------> host defenses Potential (pathogenicity) 1. Transport to host 1. Physical barriers 2. Colonization 2. Chemical barriers 3. Evasion of host defenses 3. Nonspecific immunity 4. Multiplication (Phagocytes) 5. Penetration 4. Specific immunity (Invasion)* (Antibodies, cell mediated) 6. Toxigenicity* *and/or
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326Mintro-zoonoses - Microbiology Overview Microbes are...

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