ch 17.txt

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rincrocci
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ch 17.txt
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  1. Chapter 17
    • 35. Describe the types of symbiotic relationships seen between humans and bacteria. Give specific examples for each type of relationship.
    • 1. Commensalism: One BENEFITS, Other UNAFFECTED. Ie: bacteria living on the skin of humans are not harmful or advantageous to human, but bacteria benefit by getting food and other benefits from skin.
    • 2. Mutualism: Both BENEFIT. Ie: in Large Intestines: some bac synth Vit B&K, which benefit humans, while at the same time the bac has warmth and Energy source in the body.
    • 3. Parasitism: One BENEFITS @ the expense of the other. Ie: E. coli in urinary tract – microorganism that if ingested can use body nutrients while harming the body (causes UTI).
  2. 36. Define Pathogenicity, Virulence, opportunist pathogen, infectious disease
    • Pathogenicity: Ability for a microbe to cause a DISEASE in the host
    • Virulence: The Degree of this pathogenicity (highly virulent-more likely to cause disease)
    • Opportunistic Pathogen: Microbe able to cause disease ONLY when host immune system is compromised.
    • Infectious Disease: Contageous diseases. Infectious dose is the minimum # of pathogens required to cause Disease SYMPTOMS. (LOWER THE ID #, the Better able to TRANSMIT disease).
  3. 37. Factors affecting pathogenicity
    • 1. Has to be able to enter host
    • 2. Has to be able to overcome host defenses
    • 3. Has to bring about poor physiological changes resulting in poor health
    • 4. Has to exit host tissue and spread with large # to other hosts
  4. 38. Describe the levels of microbes and the patient’s symptoms and response for the different phases of an infectious disease.
    • Acute Infection: If an organism disappears after illness
    • Chronic Infection: Illness persists over long period of time
    • Latent infection: Illness may reoccur(although you may not present symptoms of illness) when immune system is weak.
  5. 39. What are Koch’s postulates and how are they used to study infectious diseases?
    • 1. The same Pathogen must be present in EVERY case of the disease
    • 2. Pathogen must be isolated from DISEASED host and grown in PURE culture.
    • 3. This pathogen must cause the same disease symptoms when pure culture is infected into a healthy host.
    • 4. This pathogen must again be isolated from the new host and shown to be IDENTICAL to the original pathogen.
  6. 40. Examples of normal flora in different parts of body
    • Nose: S. aureus
    • Mouth & Throat: Streptococcus
    • Skin: P. acnes & Staphylococcus epidermidis
    • Vagina & Urethra: Streptococcus
    • Large Intestines: E. coli
  7. 41. Different strategies of a successful pathogen
    • ADHESINS: Allow pathogen to adhere to a cell SURFACE
    • CAPSULES: Help to AVOID phagocytosis (hide from immune system)
    • ANTIGENIC variation: Surface Changes that do NOT allow antibody binding (DOESN’T recognize the pathogen)
  8. 42. Describe three mechanisms that bacteria can use to survive within a phagocytic cell.
    • 1. Secrete same enzyme as host secretes C3B. If that doesn’t work, step 2. ESCAPE from Phagosome: bac able to escape from phagosome before it fuses with lysosome. Som form pores to escape into cytoplasm.
    • 2. Preventing Phagosome-lysosome fusion: to prevent exposure to degradative enzymes and other toxic components of lysosomes.
    • 3. Surviving within phagolysosome: has capsule can delay fusion of phagosome with lysosome, allowing additional time to equip itself for growth inside this fusion.
  9. 43. Acute, chronic and latent infections
    • Acute Infection: If an organism disappears after illness
    • Chronic Infection: Illness persists over long period of time
    • Latent infection: Illness may reoccur(although you may not present symptoms of illness) when immune system is weak.
  10. 44. What is a carrier?
    A host that has the pathogen, but no symptoms of the disease. The disease is then passed on and infects the people with the disease once it has been transmitted.
  11. 45.Exotoxin VS Endotoxins (compare and contrast)
    • ENDOTOXIN: Part of Gram – bac. Part of the OUTER membrane of Gram – bac cell wall. Can’t form a toxoid. Heat StableLipopolysaccharide triggers innate immune responseLeads to FEVER, bp drop. Small amounts can help clear infection but systemic distribution is DEADLY
    • EXOTOXIN: Gram + & - bac. Synthesized in the cytoplasm of bac, may or may not be secreted. Forms toxoid. Inactivated by HEAT
    • Proteins - very POTENT, some of the most potent in the world.
    • IE: Cytotoxins (kill or damage host cells), Neurotoxins, Enterotoxins (affect digestive tract)
    • BOTH PRODUCE: Fever, chills, weakness and Blood clots, sometimes death

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