Week 3 Flashcards
Which disease does C1-INH deficiency cause? Why?
Hereditary angioedema. C1-INH normally inhibits bradykinin formation. Without C1-INH, enzymes make bradykinin like crazy and patients get edema, vasodilation.
What species of bacteria are people who have a C5-C9 deficiency particularly susceptible to?
Neisseria species
What is the cause of membranoproliferative glomerulonephritis type II?
C3 Nephritic Factor - an autoantibody that prolongs the half-life of C3bBb –> lots of C3a and C3b generation –> immune complexes build up in glomeruli –> inflammation
Your pediatric patient has recurrent bacterial skin infections, and the umbilical stump took 3 weeks to fall off. What is your Dx?
LAD-1 (CD18 integrin defect)
What causes atypical hemolytic uremic syndrome?
Factor I, Factor H, or MCP deficiency
Which organisms are people with chronic granulomatous disease susceptible to being infected with?
Any catalase positive organisms cuz they can deal with the small bit of ROS that are made by phagocytes of people with CGD.
What test is performed to evaluate for chronic granulomatous disease? How does it work?
DHR test - flow cytometry measures amount of ROS-induced fluorescence. No fluorescence = no ROS = CGD.
What test is performed to evaluate for complement protein deficiency? How does it work?
CH50 test: put a dilution of serum in a test tube with sheep blood and measure the concentration needed to lyse 50% of the sheep RBCs.
How does Factor H work?
- It competes with Factor B (alternative pathway) to keep C3b from forming the C3 convertase.
- Factor H can displace Factor B and inhibit C3bBb after it has formed.
- Factor H recognizes oligosaccharides on human cells and gets rid of C3bBb from these cells.
What is Decay Accelerating Factor and what does it do?
DAF is membrane-bound to cells and inhibits C4b in the classical pathway from cutting C2 into C2a and C2b.
It can also inhibit C3bBb in the alternative pathway.
What is CD59 and what does it do?
Membrane-bound inhibitor of C9 polymerization in the formation of the MAC complex.
What is the difference between a type 1 and type 2 necrotizing soft tissue infection?
Type 1 is polymicrobial - grey discharge, stinky, often located in the perineal area.
Type 2 is from Strep pyogenes (or Staph, aureus or Pseudomonas less commonly) - history of blunt trauma is common.
Why should you give clindamycin in addition to penicillin G for treatment of GAS necrotizing fasciitis?
Clindamycin is a protein synthesis inhibitor so it will reduce toxin production.
Which organisms that cause necrotizing soft tissue fasciitis are associated with fresh or brackish water exposure?
Vibrio species and Aeromonas hydrophilia
What are the two most common bacterial causes of impetigo?
Staph aureus and Strep pyogenes
