MCB Exam4 A

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bkheath
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79910
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MCB Exam4 A
Updated:
2011-04-16 01:55:49
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Controlling microbial growth
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Controlling microbial growth I
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  1. Chemical method of control which dislodges bacteria from hands; reduce surface tension of solvents to make them more effective at dissolving solutes
    Surfactants
  2. Chemical method of control which is colorless, tasteless, harmless to humans, and antimicrobial & used in medical settings
    Quats = quaternary ammonia compound
  3. How are heavy metals antimicrobial?
    Metal ions alter 3-D shape of protein so no longer functions
  4. What is used on babies to prevent blindness caused by N. gonorrhoeae?
    1% silver nitrate
  5. What metal inhibits algal growth by interfering w/chlorophyll, so it's used in fish & water storage tanks?
    Copper
  6. 3 basic principles of antimicrobial therapy
    • 1. Selective toxicity
    • 2. Reach site of infection at inhibitory concentrations
    • 3. Penetrate & bind to target
  7. Exploiting differences in structure & metabolism of pathogens and host cells
    Selective toxicity
  8. 5 modes of action of antimicrobials- what is inhibited or damaged in microbial cell
    • 1. Synthesis of cell wall
    • 2. Synthesis of proteins
    • 3. Synthesis of nucleic acids
    • 4. Damage cell membrane
    • 5. Structural Analogues
  9. Example of disruption of cytoplasmic membrane
    Amphotericin B (polyene) attaches to ergosterol in fungal membranes which makes the cell wall leaky
  10. Drug which disrupts cytoplasmic membranes of Gram-negatives; toxic to human kidneys so given as last resort
    Polymyxin
  11. Drug which binds to particular enzyme involved in a bacterial metoblic pathway
    Trimethoprim
  12. 2 drugs which target viral metabolism
    Amantadine & rimantadine
  13. Example of a structural analog- Growth factor analog structurally related to PABA which inhibits microbial growth by inhibiting folate synthesis
    Sulfanilamide
  14. Why are drugs that inhibit bacterial nucleic acid synthesis toxic to human cells also?
    Only slight differences b/w prok & euk DNA
  15. _____ and _____ (2 drugs) act against prok DNA gyrase
    Quinolones, fluoroquinolones
  16. Drug binds to and inhibits action of RNA polymerase during transcription
    Rifampin
  17. General term for drugs that prevent attachment by peptide in viruses
    attachment antagonists
  18. What are the 2 general HIV drugs used
    • Reverse Transcriptase Inhibitors: prevents RT enzyme from turning RNA into DNA; ex: AZT
    • Protease Inhibitors: protease cuts DNA, so this is inhibited
  19. Lowest concentration of a substance that inhibits growth of a test organism
    Minimum inhibitory concentration (MIC)
  20. Test which uses antibiotic-impregnated wafers to test whether particular bacteria are susceptible to specific antibiotics
    Kirby-Bauer
  21. 3 main categories of side effects
    • Toxicity
    • Allergies
    • Disruption of normal microbiota
  22. Organs that are especially susceptible to toxicity
    • Liver: maintains amt of chemicals in body & removes them
    • Kidneys: excrete these chemicals
    • Also, nerves
  23. Resistance by bacteria is acquired 2 ways:
    • New mutations of genes
    • Exchange of R-plamids
  24. Multiple resistance is caused by:
    exchange of R-plasmids
  25. Bacteria that are resistant to many drugs
    Superbugs
  26. When bacteria is resistant to one drug, as well as all other drugs that are in the same family
    Cross resistance
  27. Spread of resistant bacteria throughout the community, outside of hospital setting
    Community transfer
  28. 2 diseases that are most problematic b/c of microbial resistance
    • Staph infection
    • TB
  29. When 2 drugs work in combination & complement each other
    Synergism
  30. Ways to reduce resistant microbes (2)
    • Maintain intake of drug long enough for microbe to be killed off completely, not just until symptoms go away
    • Limit use of antimicrobials
  31. Cellular mechanisms of antibacterial resistance (3)
    • Altered target: target site or enzyme become altered
    • Altered uptake: can increase impermeability of cell wall by losing porins, or by pumping drugs out of cell (efflux)
    • Drug inactivation: producing enzymes which inactivate antibacterial
  32. 2 major types of antifungals
    • azoles
    • polyenes
  33. Antifungal which inhibits cell mem synthesis by blocking biosynthesis of ergosterol
    Azoles
  34. Antifungal which affects function of cell membrane by binding to sterols in it, which causes leakage of cellular compenents & cell death
    Polyenes (Amphotericin B)
  35. Who produces antibiotics in nature (antagonism)
    (3)
    • Streptomyces: bacteria
    • Bacillus: bacteria
    • Penicillium: fungi

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