Microbio 10

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Microbio 10
2012-03-19 20:40:34
Microbio 10

Microbio 10
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  1. What is sterilization?
    the killing or removal of all viable organisms (including endospore)
  2. What is inhibition?
    Effectively limiting microbial growth
  3. What is decontamination?
    The treatment of an object to make it safe to handle
  4. What is disinfetion?
    Directly targets the removal of all pathogens, not necessarily all microorganisms
  5. What are the physical methods of antimicrobial control?
    Heat, Radiation, Filter
  6. What are the chemical methods of antimicrobial control?
    • Used on external surfaces: sterilants, disinfectants, sanitizers, antiseptics
    • Used internally: antibiotics, anivirals, antifungals
  7. What is the most widely used method of controlling microbial growth?
  8. What do high temperatures do to macromolecules?
    High temperatures denature macromolecules
  9. What is the decimal reduction time?
    Amount of time required to reduce viability tenfold is called the decimal reductio time (D)
  10. What is the thermal death time?
    Thermal death time is the time needed to jill all cells at a given temperature
  11. What is thermal death time dependent on?
    Thermal death time is dependent on the population size of the microorganism tested. Need to standardize the starting number of ells to be able to compare the sensitivity of different microorganisms
  12. What is the autoclave?
    • The autoclave is a sealed device that uses stame under pressure:
    • Allows temperature of water to get above 100°C
    • At 15psi, steam reach 121°C, sterilization is achieved in 10-15 min
    • The object being sterilized wil reach this temperature. Not suitable for heat-sensitive object/liquid
    • Not the pressure that kills things, but the high temperatures
  13. What is pasteurization?
    • Pasteurization is the process of using precisely controlled heat to reduce the microbial load in heat-sensitive liquids
    • Does not kill all organisms, it is not a method of sterilization
  14. What pathogens does pasteurization reduce significantly?
    • Listeriamonocytogenes
    • Salmonella enterica
    • Campylobacter
    • E. Coli O157:H7
  15. What is flash pasteurization?
    72°C for 15 seconds
  16. What is bulk pasteurization?
    65°C for 30 mins
  17. How is UV used for antimicrobial control?
    • UV has sufficient energy to cause modifications and breaks in DNA, which inhibit replication, transcription and cause microorganism death
    • UV is useful for decontamination of surfaces
    • Cannot penetrate solid, opaque, or light-absorbing surfaces
  18. What is ionizing radiation?
    • Electromagnetic radiation that produce ions and other reative molecules
    • Generates electrons, hydroxyl radicals, and hydride radicals
    • Amount of energy required to reduce viability tenfold is analogous to D value
  19. What are some sources of radiation?
    • Cathode ray tubes (electrons)
    • X-Rays
    • radioactive nuclides
  20. What is radiation used for?
    Radiation is used for sterilization in the medical field and food industry
  21. Why is filter sterilization used?
    • Filtration avoids the use of heat on sensitive liquids and gases
    • Pores of filter are too small for organisms to pass through
    • Pores allow liquid or gas to pass through
  22. What are depth filters?
    • Fibrous sheet or mat made from an array of fiber (paper or glass)
    • Use to sterilize liquid, air
    • HEPA filters
  23. What are membrane filters?
    • Function more like a sleve
    • A type of membrane filter is the nucleation track (nucleopore) filter
    • Filtration speed can be increased by syringe, pump, or vacuum
  24. What are the 3 classifications of antimicrobial agents?
    • Bacteriostatic
    • Bacteriocidal
    • Bacteriolytic
  25. What is bacteriostatic?
    Inhibit growth of microorganism
  26. What is bacteriodical?
    Kill microorganism
  27. What is bacteriolytic?
    Kill microorganism by inducing lysis
  28. What is minimum inhibitory concentration (MIC)?
    • The smallest amount of an agend needed to inhibit growth of a microorganism
    • Varies with the organism used, inoculum size, temp, pH, etc
  29. What is Minimym lethal concentration (MLC)?
    The lowest concentration of an agent that kills a test organism
  30. What is minimym bacteriodical concentration (MBC)?
    The lowest concentration of an agent that kills a test bacterium
  31. What is disc diffusion assay?
    • Antimicrobial agent added to filter paper disc
    • MIC is reached at some distance
    • Zone of inhibition- area of no growth around disc
  32. What is the zone of inhibition?
    Area of no growth around disc
  33. What are the two classifications of chemical antimicrobial agents?
    • Products used to control microorganisms in commerical and industrial applications
    • Products designed to prevent growht of human pathodens in inanimate environments and on external body surfaces
  34. What are some examples of products used to control microorganisms in commerical and industrial applications?
    • Chemicals in foods
    • Air-conditioning cooling towers
    • Textile and paper products
    • Fuel tanks
  35. What are some examples of products designed to prevent growth of human pathogens in inanimate environments and on external body surface?
    • Sterilants
    • Disinfectants
    • Sanitizers
    • Antiseptics
  36. What are sterilants?
    • Destroy all forms of microorganism, including endospore
  37. What are disinfectants/Sanitizers?
    • Applied to nonliving obects or surface (can be toxid for animals/humans)
    • Does not kill endospore
  38. What are antiseptics?
    • Applied to the surface of living tissues or skin (must not be toxic for anials/humans)
    • Does not kill endospore
  39. What are antimicrobial drugs?
    • Antibiotics, antitifungals, antivirals: applied outside or inside the body of animals/humans (must not be toxic for animals/humans)
    • Does not kill endospore
  40. How do phenol/phenolics act as antimicrobial agnets?
    Disinfectant/antiseptic- distrupt cytoplasmic membrane, protein denaturant (high concentration)
  41. How do alcohols act as an antimicrobial agent?
    Disinfectant/Antiseptic- Lipid solvent and protein denaturants
  42. How do halogens act as antimicrobial agents?
    Disinfectant/Antiseptic/Sterilant- Chlorine (S/D): oxidizing agent- Iodine (A): iodinate tyrosine residues in protein, oxidizing agent
  43. How do heavy metals act as antimicrobial agents?
    Disinfectant- modify proteins, interact ith RNA, DNA...severalo different mechanism
  44. How do quaternary ammonium act as antimicrobial agent?
    Interact with phospholipids of cytoplasmic membrane
  45. How do alkylating agents act as antimicrobial agnets?
    Disinfectant/Sterilant- Ethylene gas, formaldehyde, glutaraldehyde. Very toxic
  46. How are antimicrobial drugs classified?
    • Molecular structure
    • Mechanism of action
    • Spectrum of antimicrobial activity
  47. What are the properties of a good antimicrobial drug?
    • NO side effects, must be far more toxic for bacteria than mammalian cells
    • Broad spectrum of activity to faciitate rapid medical intervention
    • Appropriate bioavailability and pharmacokinetic (must reach the site of infection)
    • Low cost to develop and manufacture
  48. What is selective toxicity?
    The ability to inhibit or kill a pathogen without affecting the host
  49. What is salvarsan?
    One of the first antimicrobial drugs, use to treat syphilis (treponema pallidum)
  50. What are growth factor analogs?
    • Structurally similar to growth factors but do not function in the cell
    • Analogs similar to vitamins, amino acids, and other compounds
  51. What are Sulfa drugs?
    • Discovered by Gerhard Domagk in the 1930s
    • Sulfanilamide is an analogue of p-aminobenzoid acid
    • Bacteriostatic
  52. What is isoniazid?
    • A growth analog effective only against Mycobacterium
    • Interferes wwith synthesis of mycolic acid
  53. What are Nucleic acid base analogs?
    • Have been formed by the addition of bromine or fluorine
    • Stop DNA replication, translation
  54. What are quiolones?
    Antibacterial compounds that interfere with DNA gyrase
  55. What are antibiotics?
    Antibiotics are antimicrobial agents naturally produced by a variety of bacteria and fungi to inhibit or kill other microoranisms
  56. How much of known antibiotics are clinically useful?
  57. What are semisynthetic antibiotics?
    Antibiotics that are modified to enhance efficacy
  58. Why do gram-positive and gram-negative bacteria very in their sensitivity to antibiotics?
    The cell wall is a major factor
  59. What are beta-Lactam antibiotics?
    • One of the most important groups of antibiotics of all time
    • Include penicillins, cephalosporins, and cephamycins
    • Btericidal, bacteriolytic
  60. What are Penicillins?
    • Discovered by Alexander Flemin, isolated from Penicillium chrysogenum (mold)
    • Primarily effective against gram-positive bacteria
    • Some synthetic forms are effetive against some gram-negatie bacteria
    • Inhibit cell wall synthesis
  61. What are cephalosporins?
    • Produced by funcus Cephalosporium
    • Same mode of action as the penicillins
    • Commonly used to treat conorrhea (Neisseria gonorrhea)
  62. What are Aminoglycosides?
    • Kanamycin, neomycin, amikacin, streptomycin
    • Target 30S subunit of ribosome, cause misreading of mRNA
    • Bactericidal
  63. What is chloramphenicol?
    • Bind to 23S rRNA and block peptide elongation
    • Bacteriostatic
  64. What are macrolides?
    • Ethromycin
    • Broad-spectrum antibiotic that targets the 50S subunit of ribosome, block protein synthesis
    • Bacteriostatic
  65. What are tetracyclines?
    • Broad-spectrum inhibition of protein synthesis, bacteriostatic
    • Inhibits functioning of 30S ribosomal subunit, block protein synthesis
  66. What is Daptomycin?
    • Also produced by Streptomyces
    • Used to treat gram-positive bacterial infections
    • Forms pores in cytoplasmic membrane
  67. What is Platensimycin?
    • New structural calss of antibiotic
    • Broad-spectrum, effective agains MRSA and vacomycin-resistant enterococci
  68. What is antimicrobial drug resistance
    The acquired ability of a microorganism to resist the effects of a chemotherapeutic agent to which it is normally sensitive
  69. What is producer tolerance?
    • Lack target sites (no peptidoglycan)
    • Modify target sites
    • Lack of uptake mechanism
  70. What is resistance mechanism?
    • Destroy or modify the antibiotic (beta-lactamase)
    • Modify the target site
    • Modify uptake mechanism
    • Efflux pumps: reduce intracellular concentration
  71. How does one acquire resistance?
    • 1. Mutation of target sites
    • 2. Plasmic acquisition
  72. What predates the antibiotic era?
    Evidence indicates that R plasmids predate the antibiotic era (antibiotics come from nature)
  73. Can R plasmids be transfered between species?
    R plasmids can be transferred between bacteria of the same species or related species
  74. What is an example of a pathogen that has developed resistance to all known antimicrobial agents?
    Methicillin-resistant S. Aureus (MRSA)
  75. How can resistance be minimized?
    Resistance can be minimized by using antibiotics correctly and only when needed (reduce selection)
  76. How do antiviral drugs work?
    • Most antiviral drugs also target host structures, resutling in toxicity (viruses use host cell machinery)
    • Risk to the host may not justify the use of antiviral
  77. Are antibiotics effective on viruses?
  78. What are the most successrful and commonly used antivirals?
    Most successful and commonly used antivirals are the nucleoside analgs (eg AZT): block reverse transcriptas and production of viral DNA (RNA viruses)
  79. What are protease inhibitors?
    Inhibit the processing of large viral proteins into individual components
  80. What are fusion inhibitors?
    Prevent viruses from successfully fusing with the host cell
  81. Why do fungi pose special problems for chemotherapy?
    Fungi pose special problems for chemotherapy because they are eukaryotic: much of the cellular machinery is the same as that of animals and humans
  82. What are a few drugs that target unique metabolic processes not found in mammals?
    • Ergosterol synthesis (nystatin, fluconazole)
    • Cell wall synthesis (inhibitor of chitin synthesis)