MICRO: FINAL TEST

• Pathogenicity


  Ability to cause disease
• virulence


  degree of pathogenicity
• What are portals of entry?

  mucous membranes, skin, wounds, parenteral route
• what is parenteral route?

  deposition directly into tissues when barriers are penetrated
• most pathogens have a preferred ______


  portal of entry
• what is ID50?


  Infectious Dose for 50% of a sample population (or tissue or cell)
• what does ID50 measure?

  virulence of a microbe
• What is LD50?

  lethal dose for 50% of a sample population (or tissue or cell)
• what does LD50 measure?

  potency of a toxin
• What does a low ID50 tell us about the preferred route of entry?

  The lowest ID50 number can tell us that this is their preferred portal of entry
• why might ingestion not be a preferred route of entry?

  acidity of our stomach will kill them
• why might respiration not be an ideal portal of entry?

  we have hairs and mucous membranes that trap bacteria and prevent them from infecting our body
• what does a low LD50 number indicate?

  High toxicity (need less to infect a person)
• What does a high LD50 number indicate?

  Low toxicity
• adherence


  attachment to host
• adhesins (ligands)


  on the pathogen bind to receptors on the host cell
• what are the different types of adhesins?

  glycocalyx (capsule, biofilm) fimbriae, pili
• How does a capsule help a bacteria evade our immune system?

  usually our immune system binds to antigens on bacteria but capsule covers up the antigen so that our white blood cells with antibodies do not detect antigen
• what are proteases?


  Enzymes secreted by bacteria to break down protein such as antibodies
• what are the bacteria’s that have a capsule?

  -Yersinia pestis

  -Streptococcus pneumoniae

  -klebsiella pneumonia

  -Haemophilus influenza

  -pseudomonas aeruginosa

  -neisseria meningitidis

  -cryptococcus neoformans
• M protein belongs to ____

  Streptococcus pyogenes
• What is an M protein?

  Virulence factor that resists phagocytosis
• Opa Protein belongs to ______

  Neisseria gonorrhoeae
• what does Opa protein do?

  allows attachment to host cells
• What is an example of a bacteria with mycolic acid?

  Mycobacterium tuberculosis
• What do coagulases do?

  coagulate fibrinogen to evade immune system
• What do kinases do?

  digest fibrin clots
• what does Hyaluronidase do?

  digests polysaccharides that hold cells together
• What do Collagenases do?

  Break down collagen
• What does IgA proteases do?

  destroy IgA antibodies
• what are antigenic variations?


  when pathogens alter their surface antigens that allows them to escape immune system and vaccines
• what are invasins?


  surface proteins produced by bacteria that rearrange actin filaments in cytoskeleton causing membrane ruffling which helps them evade mucous by being held by microvilli and they cannot be swept away
• which bacteria can use actin to move from one cell to the next?

  Shigella and listeria
• What is required for most pathogenic bacteria?

  Iron
• what makes shigella so virulent?

  uses actin to move from one cell to the next without having to cross mucous membranes again
• What are some examples of mucous membranes?

  Respiratory, gastrointestinal, urogenital, and conjunctiva
• what is a extracellular structure with components involved in attachment to host

  adhesin
• what is a carb-binding protein on surface of microbes; attachment to host?

  glycocalyx
• what is an appendage on bacteria used for attachment to host cells?

  fimbriae
• what is an enzyme that protects bacteria from phagocytes and antibodies by clotting blood?

  coaglase