MicB 3301 Final Review

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MicB 3301 Final Review
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2010-05-13 19:05:42
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  1. Salmonella typhimurium and E. coli O157: H7
    • food/water borne pathogens
    • S. typhimurium used by cults to try to sway votes (bioterrorism)
  2. LD50=Lethal Dose 50
    • number of pathogens that will kill 50% of an experimental group of hosts
    • lower LD50=more virulent
  3. Viral infection steps
    • 1. host contact/entry
    • 2. replication
    • 3. spread
    • 4. cellular injury
    • 5. host immune response.
    • 6. clearance, persistance, or death of host
  4. syncytia
    large mass/fusion of cells; multinucleated. forms in response to viral infection
  5. tropism
    • specific site of infection (cell/tissue/organ)
    • receptor dependent
  6. viral attachment and spread: roles of N and H on the influenza virus
    • H=hemaglutinin=attachment
    • N=neuraminidase=spread; cleaves host lipids and glycoproteins
  7. ways viruses avoid immune recognition and host response
    • 1. block cytokine (interferon) synthesis
    • 2. breakdown complement proteins
    • 3. block production of complement proteins
    • 4. block antigen processing of MHC export
    • 5. antigenic variation (i.e changing the a.a. sequence in virion spikes)
  8. Interferons
    • antiviral cytokines: important in viral resistance during early stages of infection
    • destroy viral mRNA
    • shut down viral translation
    • stimulate CTLs and NKs
  9. bacterial adherence factors
    • capsules
    • pili
    • M protein
  10. coagulase
    • virulence factor that clots sera, forms a shield that protects pathogens from phagocytosis
    • ex) S. aureus
  11. streptokinase/fibrinolysin
    • Virulence factor that binds plasminogen and digests fibrin clots. Allows movement and spread
    • ex) Staphylococcus, Streptococcus
  12. hemolysins
    • virulence factors that lyse RBCs and make Fe available to bacteria
    • ex) staphylococcus, streptococcus, E. coli
  13. collagenase
    • virulence factor that breaks down collagen and allows bacterial spread
    • ex) Clostridium sp.
  14. IgA protease
    • virulence factor that cleaves IgA into Fc/Fab fragments
    • ex) Streptococcus pneumoniae
  15. bacteremia vs. septicemia
    • bacteremia=presence of bacteria in the bloodstream
    • septicemia=growth/division of bacteria in the bloodstream
  16. M protein (2 roles)
    • 1. adhesion of bacteria to host cell
    • 2. block adhesion of phagocytes to bacterium
  17. Bacterial evasion of host defenses (4 methods)
    • 1. Resist the complement system: cleave c5a, lengthen LPS, capsules
    • 2. avoid specific immune responses: capsules, antigenic variation, IgA proteases
    • 3. avoid phagocytosis: capsule, proteins that block adherence (M protein), leukocidines, coagulase
    • 4. survival inside phagocytic cells: phagosome escape or resistance to ROS and NO, prevent phagosome-lysosome fusion
  18. 3 intracellular pathogens
    • 1. Listeria monocytogenes
    • 2. Legionella pneumophila
    • 3. Mycobacterium tuberculosis
  19. Listeria monocytogenes
    • intracellular pathogen
    • uses host cell actin polymerization
    • doesn't enter extracellular space or illicit an immune response
  20. Legionella pneumophila
    • intracellular pathogen
    • inhibits phagosome-lysosome fusion
  21. Mycobacterium tuberculosis
    • intracellular pathogen
    • inhibits phagosome-lysosome fusion
    • can escape phagosome to cytoplasm
  22. Biofilms
    • microbial communities attached to a surface and covered by a polysaccharide matrix
    • protected from immune response and antibiotics
    • produce virulence factors under QS control
  23. otitis media
    • infection of the inner ear
    • Streptococcus pneumoniae
    • recurring infections due to biofilm protection from antibiotic treatment
  24. cystic fibrosis
    Pseudomonas biofilms in the lungs
  25. Endocarditis
    Staphylococcus or Enterococcus biofilms on heart valves
  26. Types of exotoxins (4)
    • 1. Membrane disrupting
    • 2. AB exotoxins
    • 3. superantigens
    • 4. specific host site exotoxins
  27. pore forming exotoxins
    • membrane disrupting exotoxin that forms pores which cause host swelling and lysis
    • ex) hemolysins release Fe
    • ex) leukocidins kill macrophages
  28. phospholipases
    • membrane disrupting exotoxin
    • cleaves host lipid bilayer between head and tail, leading to instability
  29. superantigens
    • exotoxins that interact with and lock MHCII receptors to TCR, which overstimulates Tcell response even in the absence of peptide
    • increases cytokines and inflammation
    • ex) Staphylococcus and toxic shock syndrome toxin
  30. AB exotoxins
    • transmembrane, 2 subunits
    • A= toxic effect
    • B= binds to target cell

    • ex) Shiga toxin
    • ex) E. coli O157: H7
  31. Diptheria toxin
    • AB exotoxin that does not form a pore via the B subunit
    • instead, it enters the host via receptor mediated endocytosis
    • at ph <5, the vesicle and A and B subunits diffuse to cytoplasm
    • A affects ADP ribosyl transferase, B goes back to membrane
  32. specific host site exotoxins
    • often AB
    • enterotoxins
    • neurotoxins
  33. enterotoxins
    • specific host site exotoxins that stimulate host adenylate cyclase which increases cAMP which causes ion imbalance and H20 loss.
    • ex) cholera toxin of Vibrio cholerae
  34. neurotoxins
    • specific host site exotoxins that block the release of Ach from the neuromuscular junctions, causing flaccid paralysis because the muscle can't contract
    • ex) botulinum toxin of Clostridium botulinum (used in Botox)
  35. toxoid
    • inactivated toxin that still illicits the immune response
    • part of vaccines
  36. DTaP
    vaccine for Diptheria, Tetanus, and Pertussis
  37. Endotoxin
    • LPS from gram (-) bacteria
    • more general effects: fever, shock, inflammation
    • causes: release of endogenous pyrogens, TNF
    • ex) meningitis, petechia--due to gram (-) shock
  38. Type III Secretion Systems (TTSS)
    • for gram (-) pathogens
    • inject effectors via injectisome
  39. injectisome parts
    needle, pore, basal body
  40. pathogenicity islands
    • large, often chromosomal DNA regions of the pathogen that encode many virulence genes (often in operons)
    • encodes: injectisome for TTSS
    • G and C content often differs from the rest of the pathogen genome...evidence for HGT
  41. Targets for TTSS
    • host cell cytoskeleton- actin
    • host cell signalling- NFkB
  42. EPEC
    • Enteropathogenic E. coli: cause of infantile diarrhea
    • ex) Type III secretion System
    • binds host cells using bundle forming pili, assembles injectisome and delivers effectors
    • *one effector is Tir-Translocated intimin receptor
    • Tir is presented on the host cell surface to bind EPEC intimin and serve as a docking station
  43. Paul Ehrlich
    • magic bullets
    • selective toxicity (to germ rather than host)
  44. Who cultured >10,000 strains of soil bacteria and isolated Streptomyces?
    Selman Waksman
  45. Alexander Fleming (1928)
    • accidentally discovered penicillin
    • Staphylococcus and Penicillium on same plate
  46. Who purified penicillum, proved its efficacy against infected animals, and shared the nobel prize with Fleming?
    • Florey
    • Chain
    • Heatley
    • (1939)
  47. cidal vs. static
    • cidal: kills pathogen
    • static: inhibits growth
  48. Antimicrobial Targets (5)
    • 1. Cell wall synthesis
    • 2. Plasma membrane
    • 3. Nucleic acid synthesis
    • 4. Protein synthesis
    • 5. metabolic enzymes
  49. Antimicrobials that target cell wall synthesis
    • betalactams (penicillin)
    • Vancomycin
    • Bacitracin
  50. Antimicrobials that target the Plasma Membrane
    • Polymyxins
    • Imidazole
    • Nystatin
  51. Antimicrobials that target nucleic acid synthesis
    • Quinolones
    • Rifampin
  52. Antimicrobials that target Protein Synthesis
    • Aminoglycosides (streptomycin, kanamycin)
    • Tetracycline
    • Macrolides (erythromycin, azithromycin)
  53. Antimicrobials that target metabolic enzymes
    • Sulfonamide
    • Triclosan
  54. Penicillins (beta lactams)
    • target PBPs (penicillin binding proteins) for transpeptidation
    • transpeptidation: energy used to cross-link NAG and NAM residues with the terminal D-Ala
    • penicillinase attack the beta lactam ring
  55. Vancomycin
    • CELL WALL SYNTHESIS INHIBITOR
    • glycopeptide antibiotic
    • binds terminal D-Ala and prevents peptidoglycan synthesis
  56. Bacitracin
    • CELL WALL SYNTHESIS INHIBITOR
    • inhibits carrier for peptidoglycan subunits
  57. Polymyxins
    • PLASMA MEMBRANE INHIBITOR
    • disrupt lipid bilayer
    • cidal against narrow spectrum gram-
  58. Imidazole
    • PLASMA MEMBRANE INHIBITOR
    • blocks synthesis of membrane sterols
    • treats athletes foot
  59. Nystatin
    • PLASMA MEMBRANE INHIBITOR
    • binds membrane sterols
    • treats Candida infections
  60. Quinolones (definition and two types)
    • NUCLEIC ACID SYNTHESIS INHIBITOR
    • inhibits DNA gyrase
    • **synthetic antimicrobials
    • ex)Nalidixic acid
    • ex)Ciprofloxacin
  61. Rifampin
    • NUCLEIC ACID SYNTHESIS INHIBITOR
    • inhibits RNA polymerase (and therefore transcription)
  62. Aminoglycosides (definition and two types)
    • PROTEIN SYNTHESIS INHIBITORS
    • prevent 30S and 50S binding
    • ex) Streptomycin
    • ex) Kanamycin
  63. Tetracycline
    • PROTEIN SYNTHESIS INHIBITOR
    • binds 30S, distorts A site, prevents amino-acyl tRNA binding
  64. Macrolides (definition and two types)
    • PROTEIN SYNTHESIS INHIBITORS
    • bind 50S rRNA, block elongation
    • ex) Erythromycin
    • ex) Azithromycin
  65. Sulfonamide
    • METABOLIC ENZYME INHIBITOR
    • metabolic analogs that inhibit folic acid synthesis
    • also inhibit purine and pyrimidine synthesis
  66. Triclosan
    • METABOLIC ENZYME INHIBITOR
    • present in plastics, toothbrushes, etc.
    • binds enoyl reductase (an enzyme for fatty acid synthesis)
  67. Acyclovir
    • ANTIVIRAL
    • inhibits DNA polymerase of herpes virus
  68. Tamiflu
    • ANTIVIRAL
    • inhibits neuraminidase to prevent spread of influenza virus
  69. HAART
    highly active antiretroviral therapy
  70. Azidothymidine (AZT)
    • HAART antiviral for HIV
    • targets reverse transcriptase
    • nucleoside analog, causes DNA chain termination
  71. Ritonavir
    • HAART anti-HIV drug
    • protease inhibitor (prevents viral assembly)
  72. Mechanisms of drug resistance
    • 1. prevent access to or alter the drug target
    • 2. create an enzyme to degrade antibiotic (ex. penicillinase)
    • 3. Alter antibiotic (ex. phosphorylation)
    • 4. efflux pumps
    • 5. resistance genes from HGT
  73. Which superbug replaces the terminal D-Ala of peptidoglycan with another amino acid?
    Vancomycin resistant Enterococcus
  74. MRSA
    has a mecA gene which encodes mutant PBP, creates low affinity for penicillins
  75. Varicella-Zoster virus
    • Herpes family
    • dsDNA, icosahedral, enveloped
    • causes Chickenpox and Shingles
  76. types of vaccines (3)
    • attenuated (live): specific genes inactivated, activates humoral and cellular immune responses, may revert
    • inactivated (killed): chemicals or irradiation, activates humoral response, requires a booster
    • VLP (Virus Like Particle): noninfectious, naked, capsid (no genome) of a virus ex) Gardisil
  77. MMR
    • Measles, Mumps, Rubella
    • all caused by RNA viruses
    • MMR vaccine=attenuated
  78. Antigenic SHIFT vs. DRIFT
    SHIFT: major antigenic changes, often the result of different strains resorting via a reservoir (ex. Swine flu)

    DRIFT: minor antigenic changes, due to mutations in N (or H) of influenza virus (ex. seasonal changes and increases in flu outbreaks)
  79. 3 conditions for (influenza) pandemic
    • 1. new antigenic influenza subtype
    • 2. infects humans, and causes serious illness
    • 3. spreads easily
  80. Arboviruses
    • =arthropod-borne viruses
    • insects=vectors
    • ex) Yellow Fever-mosquito
    • ex) West Nile Fever-mosquito and birds
    • RNA flavoviruses
  81. Zoonotic viruses cause ________
    ex)
    • hemorrhagic fevers
    • ex) fruit bats and the Ebola virus (filamentous morphology)
    • viral proteins cause blood clotting, interferon blocks, and hemorrhaging
  82. A disease of animals that can be transmitted to humans is a _______ disease.
    zoonotic
  83. direct contact diseases (4)
    • HIV/AIDS
    • Common Cold
    • Mononucleosis
    • Hepatitis
  84. HIV
    • enveloped, icosahedral, RNA retrovirus
    • enzymes and proteins: gp120, protease, reverse transcriptase, integrase
    • life cycle: in a CD4+ Th cell, genome integrates (provirus), uses host machinery to assemble capsid
    • pathogenesis: depletion of T cells and APCs (dendritic cells)
  85. CDC definition of AIDS
    • Acquired Immune Deficiency Syndrome
    • HIV infected individual with <200 CD4+ T cells per uL of blood
  86. Rhinovirus
    • Major cause of the common cold
    • ssRNA+, naked, icosahedral
    • >100 different serotypes
  87. ICAM-1
    • cell-surface receptor for Rhinoviruses
    • Intracellular Adhesion Molecule-1
  88. EBV=Epstein-Barr Virus
    • type of herpesvirus; cause of Mononucleosis
    • infects epithelial cells and then B cells
    • icosahedral, enveloped, dsDNA
  89. What virus causes Mononucleosis?
    Epstein Barr Virus
  90. Hepatitis
    • 11 viral causes (2=herpesviruses, 9=hepatotropic viruses)
    • inflammation of the liver
  91. Hepatotropic Viruses
    • multiple modes of transmission
    • cause Jaundice, hepatitis
    • treatment: vaccines, recombinant interferon therapy
  92. Rotavirus
    • (1 of 2) viral gastroenteritis
    • NSP4=viral enterotoxin that promotes fluid secretion
  93. Norovirus
    • (1 of 2) viral gastroenteritis
    • naked, RNA
    • outbreaks on cruise ships, at oscar parties
  94. Poliovirus
    • causes polio (infantile paralysis)
    • naked, icosahedral, +ssRNA
    • stable in food and water
    • targets motor nerve cells in spinal cord, creates paralysis
    • treatement: attenuated and inactivated vaccines available
  95. Mycobacterium tuberculosis (TB)
    treatment?
    • cause of TB (intracellular pathogen)
    • waxy coat/cell wall that allows identification by acid fast staining
    • treatment: iconiazid and rifampin
  96. Streptococcal diseases/pathogens?
    Treatment?
    • Streptococcus pyrogenes and Streptococcus pneumoniae
    • infections of the skin, throat, lungs
    • Treatment: penicillins, macrolides (erythromycin)
  97. flesh eating bacteria
    • necrotizing fasciitis
    • Invasive Streptococcus pyrogenes infection
  98. Whooping cough
    • Bordetella pertussis (Gram -)
    • virulence factors: pili, siderophores, Ptx
    • Ptx: targets adenylate cyclase (increases secretions, mucus)
    • treatment: Augmentin
  99. Augmentin
    • Rx for Whooping Cough/Bordetella pertussis
    • Amoxicillin component inhibits cell wall synthesis
    • Clavalanate component impedes beta lactamases
  100. Meningitis microbes (3)
    • Haemophilus influenzae
    • Streptococcus pneumoniae
    • Neisseria meningitidis**
  101. Neisseria meningitidis
    • one cause of meningitis
    • gram (-): LPS->TLR4->TNF->PMNs from blood vessels
    • virulence factors: endotoxin, pili, capsule
  102. The Plague
    • Yersinia pestis
    • 2 types: Bubonic and Pneumonic
    • Bubonic: fleas spread, lymph nodes to rest of body forming bubos
    • Pneumonic: humans, flu-like initially but 100% fatal if untreated
    • Uses a Type III secretion system
  103. Lyme Disease (organism, stages, treatment)
    • Borrelia burgdorferi
    • stages: 1-localized, 2-disseminated, 3-late
    • treatment: Tetracyclines, Penicillins
  104. Anthrax (organism, toxin type, treatment)
    • Bacillus anthracis
    • Toxin: AB but three parts
    • cutaneous vs. respiratory
    • Treatment: Quinolone (ciprofloxacin)
  105. Anthrax toxin (Bacillus anthracis)
    • AB but three parts:
    • PA=protective antigen (B)
    • EF=edema factor (A)
    • LF=lethal factor (A)
    • encoded on plasmid and enter cell when the three toxins associate
  106. receptor interference
    Concept that viruses are selfish and prevent superinfection by removing entry receptors from the cell surface once they have infected it
  107. Cholera
    • Vibrio cholerae gram (-)
    • cholera toxin increases adenylate cyclase, causes ion imbalance and H20 hypersecretion
  108. Botulism
    • Clostridium botulinum
    • botulinum toxin: prevents Ach release from neuromuscular junctions, causes flaccid paralysis and cardiac failure
  109. Food and water-borne pathogens (2)
    • Salmonella typhimurium: causes acid stress response in stomach, activates a specific set of genes in the human GI system
    • E. coli 0157:H7: carried by cattle, produces shiga-like AB toxin, that cleaves rRNA. Encoded on a temperate phage (which makes treatment difficult)
  110. Major fermentations (3)
    • Lactic (cheese and yogurt)
    • Propionic
    • Ethanolic (alcohol)
  111. Lactic acid fermentation pathway
    balances with glycolysis (NAD+-->NADH reduction, ADP-->ATP)

    2 pyruvate-->2 lactate. NADH-->NAD+ oxidation, no ATP required
  112. yogurt bacteria
    • Lactobacillus and/or Streptococcus (Starter Culture)
    • "Lactic Acid Bacteria" gram (+)
  113. Bio-based plastic
    • "polylactide"
    • E. coli and Lactobacillus
  114. Cheese Production
    milk--1-->curd--2-->cheese

    • 1=Lactococcus starter culture and renin
    • 2=ripening by microbial action (microbe varies for each type of cheese)
  115. Microbe for swiss cheese (step 2)
    Propionibacterium
  116. Microbe for bleu cheese (step 2)
    Penicillium roqueforti
  117. Pro-Biotics (brand names, microbes, benefits)
    • Brand names: Serovera, Activia, Bifantis
    • Microbes: Lactobacillus, Bifidobacterium
    • Benefits: compete with unwanted organisms, produce antimicrobial compounds, etc.
  118. Steps/microbes for wine production (2)
    • Sacchromyces ferments the must (from grapes/juice)
    • Leuconostoc sp. undergo malolactic fermentation (malic acid to lactic acid)
  119. Secondary metabolite
    • compound that accumulates during period of nutrient limitation following active growth (aka stationary phase)
    • ex) Penicillin G and other ANTIBIOTICS
  120. Bioremediation
    Using microbes to degrade pollutants
  121. alkane hydroxylase
    enzyme (from microbes) to use to clean up oil spills--some microbes can use that carbon as a source of energy

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