Bacterial Disease

  1. Pathogen
    Bacteria capable of harming a "normal" host
  2. Virulence
    Degree of pathology caused by the organism (quantitative)
  3. Why can't Transient microbiota remain in the body for extended periods of time?
    • Competition from resident microbes
    • Immune elimination
    • Chemical changes that discourage growth
  4. How can bacteria provide nutritive benefits to a host?
    • Synthesis of vitamins (own needs)
    • steroid metabolism (bile acids)
    • organic acid production (acetic acid)
    • glycosidase reaction (sugar fermentation)
  5. where is the vast majority of normal flora?
    Gastrointestinal tract
  6. Quorum Sensing
    • Coordinated chemical sensing between cells
    • autoinducers = signalling molecules
  7. Why are biofilms antimicrobial resistant?
    • EPS mesh barrer
    • Nutrient barrier (slow growth= antibiotic resistance)
    • Persistor cells (repopulation
  8. Why might it be harder for an antibiotic to treat a gram-negative bacterial infection?
    Gm-'ve outer membrane can be selectively permeable.
  9. lactoferrin
    iron-binding protein that acts as an immediate antimicrobial defence
  10. lactoperoxidase
    enzyme that generates singlet oxygen to kill bacteria. antimicrobial.
  11. fibrinogen
    forms a fibrin clot around the "wall" of a damaged host cell for infection localization
  12. List possible antibiotic resistance mechanisms of bacteria.
    • mutations in target¬†
    • efflux pump removal
    • degrading enzymes
    • decreased cell-wall permeability
  13. Passive immunization
    iinjecting of pre-formed antibodies raised agains a specific bacteria into an infected person. (not common)
  14. Koch Postulate #1 ; problem with this?
    • Suspected pathogenic organism should be present in all cases of the disease and absent from healthy animals.
    • ; Individuals can carry pathogens, but not get disease
  15. Koch postulate #2; problem?
    • Suspected pathogen should be grown in pure culture
    • ; some pathogens cannot be grown in pure culture (viruses)
  16. Koch's postulare #3? ; problem?
    • Cells of the pure culture of the suspected pathogen should cause the same disease in a healthy animal.
    • ; Pathogens can cause disease in one species but not another
  17. Koch's postulate #4? ; problem?
    • Pathogen must be re-isolate from the diseased animal and show to be identical to the original suspected pathogen
    • ; Pathogen may not grow in pure culture (virus)
  18. endemic
    low continual frequency of disease
  19. pandemic
    worldwide epidemic (sporadic outbreaks between continual low level)
  20. Two component system
    • Virulence genes are regulated by a sensor and a regulator.¬†
    • autophosphorylation, phosphate transfer for transcription activation
  21. What does the host response to N. Gonorrhoeae consist of?
    • anti-microbial peptide production
    • antibody production
    • shedding/ destruction of colonized host cells
  22. How does N. Gonnorrhoeae bacteria evade the hosts adaptive immune response?
    • Antigenic variation
    • Phase variation
  23. PicC protein is important as..
    • an adhesin
    • proper assembly of pilus (adhesion, DNA uptake)
  24. Opa
    • N. Gonorrhoeae adhesin protein
    • important for neutrophils to phagocytose
  25. How can pilE loci of the pilC be expressed while pilS loci are silent?
    pilE contains the portion that codes for the conserved N-terminus of the protein
  26. phase variation
    the process of turning on or off the expression of a particular gene product (Opa proteins in N. Gon)
  27. Antigenic variation occurs prominently in the _-terminal region of pilin.
    C-terminal (N-terminal region of pilin is highly conserved)
  28. how does the S. Pneumoniae polysaccharide capsule prevent phagocytosis?
    • Prevents deposit of antibody or peptidoglycan on bacterial surface
    • prevents the formation of C3b complex (complement pathway opsonization)
  29. Exotoxins
    • proteins secreted by Gm+ & Gm- bacteria
    • may cause damage far from bacterial colony site
    • heat sensitive
    • immunogenic
  30. Enterotoxin
    • type of exotoxin
    • affects cells lining the GI tract, causing massive fluid secretion
  31. Why cant a vaccine be used to treat endotoxin shock? (fluid leak, inflammation, coagulation)
    • edotoxins are non-protein molecules¬†
    • and are not very immunogenic
  32. SPI I encodes TTSS that is associated with...
    • Cell invasion
    • Gastroenteritis
    • Pro-inflammatory cytokine release
    • macrophage apoptosis
    • invasion of epithelial cells
  33. SPI-2 ecodes a TTSS associated with
    • intracellular survival
    • replication (mice)
    • macrophage cytotoxicity (mice)
    • systemic disease (mice)
  34. How does SPI-2 avoid phagosome-lysosome fusion?
    Injects proteins and modifies membrane of vacuole it is inside.
  35. What are the TOP 4 diseases of bioterrorist threats
    • Anthrax
    • Smallpox
    • Plague
    • Botulism
  36. Anthrax
    • Gm+
    • Spores
    • edema toxin
  37. Plague
  38. Botulinum
    • Gm+
    • Spores
    • Paralysis
Card Set
Bacterial Disease
micb 202 bac cards