Module 19 Flashcards
Define Pathogenicity
property to cause disease
-portal of entry
-how many enter
-adherance
-invasion and damage to host
-portal of exit
What are the three main portals of entry?
Mucous membranes
Intact Skin
Parenteral
Explain/define/list characteristics of each route and know examples of microorganisms that use these routes (examples of diseases).
Mucous membranes
-respiratory tract, most frequent, easiest entry point (dust, drops of moisture)
–cold, pneumonia, TB, measles
-GI tract, acid and bile resistant, contaminated food and water
–dysentery, Hep A, cholera
-Conjunctiva
–conjunctivitis, trachoma
Intact skin
-through hair follicles and sweat glands
–ringworm, athlete’s foot
Parenteral route
-beneath skin in punctures/injections, bites, cuts, surgery
–gangrene, dengue fever, staph
What does LD50 and ID50 stand for?
Lethal Dose for 50% of hosts
ID-number needed to cause disease in 50%
Why is adherence an important mechanism of pathogenicity? What molecules do microbes use for adherence?
Use adhesions or ligands important to attach to host cell receptors
What are the seven ways that bacteria resist or avoid the immune system?
Capsules-impairs phagocytosis, adherence, nutrient reserve.
Proteases to digest antibodies-secreted from metabolism of bacteria to outside of cell
M protein-structural protein, functions in attachment and prevents phagocytosis by WBC
Mycolic Acid-Waxy lipid found in cell wall of Mycobacterium sp., resistant to phagocytotic digestion.
Coagulase-causes blood clotting, prevents access to bacteria from WBC by forming a barrier
Kinases-dissolve clots that body forms to isolate infection, produced by gram+ cocci
What are the functions of capsules?
Capsules-impairs phagocytosis, adherence, nutrient reserve.
What is the function of the M protein?
M protein-structural protein, functions in attachment and prevents phagocytosis by WBC
What is mycolic acid and what is its function?
Mycolic Acid-Waxy lipid found in cell wall of Mycobacterium sp., resistant to phagocytotic digestion.
What is the difference between coagulase and kinase?
Coagulase causes blood clotting while kinases dissolve clots
What is an exoenzyme?
Coagulase-excreted outside of the cell
What is Hyaluronidase and Collagenase? DNAse?
Break down connective tissue which helps bacteria spread from initial infection site
Break down DNA to help bacteria spread
What are invasins?
Proteins which rearrange cytoskeleton to enter a cell
Produce actin baskets or cause membrane ruffling
What were the main substances we talked about which cause host damage?
Toxin
What is the major endotoxin? What portion of this molecule?
LPS-Lipid A Portion
