BIO205 CASE STUDY CH6,9 10, 11

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BIO205 CASE STUDY CH6,9 10, 11
2013-02-23 00:46:34

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  1. The bacterial biofilm that caused Betty's septicema is likely to return to the surface of the teeth. why?
    Biofilms are communities composed of numerous bacterial species that live within amatrix of tangled fibers and sticky molecules. Even when the bacteria are scraped off, afew remaining individual bacterial cells are able to recolonize and rebuild the biofilm. Thisis why teeth cleaning is recommended every six months.
  2. When septicema is suspected, blood samples are placed into nutritive media.  What growth requirements are necessary in the media to ensure that bacteria from the blood specimen will thrive?
    Protein, carbohydrates, water, and electrolytes are necessary components of the media toenable bacteria to grow and reproduce. In addition, the media must be incubated at bodytemperature, and the appropriate level of oxygen must be present.
  3. What is it about the freezing process that can help minimize the risk in microorganisms in sushi?
    At low temperatures, the chemical reactions of microbial metabolism take place very slowly,if at all. This means that microbes cannot grow and reproduce to cause food spoilage.
  4. How can soaking raw fish in very salty water inhibit the growth of bacteria?
    High salt concentrations create osmotic pressure, which causes cells to lose water. Becauseenzymes and substrates must be in solution to interact, cell metabolism is inhibited. Bacterialgrowth stops.
  5. What is the mechanism of action for beta-lactams?
    The beta-lactam drugs interrupt bacterial growth by preventing cell wall production.
  6. how do bacteria become resistant to beta-lactams?
    Bacteria become resistant by producing enzymes that interfere with the action of the drugs,breaking down the central structure (beta-lactam ring), or by preventing entry of the druginto the cell.
  7. what conditions, caused or complicated by sean's diabetes, created a unique environment for C. perfringens to grow?
    The decreased peripheral circulation resulted in decreased oxygen to the tissues, creatingan environment anaerobes require. In addition, the nerve damage decreased Sean’s abilityto feel the presence of infection, resulting in tissue damage that further decreased oxygensaturation. Accumulation of dead tissue inhibits both Sean's immune system and theantibiotics from fighting the infection.
  8. What characteristics of clostridia contributed to the foul smell that permeated the room when the nurse debrided the wound?
    Clostridium perfringens, like other anaerobes in the classification Firmicutes, is able toreduce sulfur, producing H2S, or hydrogen sulfide. This chemical creates a nearlydiagnostic “rotten egg” smell associated with Clostridium perfringens infections.