Micro facts from non Micro chapters/ hard to remember Flashcards
Strep Pyogenes - virulence factors
- Streptococcal chemokine protease - degrades IL-8 from neutrophils
- C5a peptidase - (-) C5a anaphylatoxin and (-) neutrophil chemotaxis
- M protein - binds serum factor H, destroying C3 convertase and (-) C3 opsonization
S. aureus Protein A function
binds Fc portion of IgG - to avoid opsonization
Pseudomonas stops complement how?
(-) C3a, C5a
How is pilli a virulence factor of Neisseria gon?
pilli are anti-phagocytic in this case ( as well as used for adherence)
List organisms that evade immune system by antigenic variation and how?
Diff in antigenic drift vs shift
Many viruses will mutate –> antigenic drift –> epidemics
ressortment of segmented virus genome –> antigenic shift –> pandemics
Mycobacterium TB - how do they survive IC?
sulfatides inhibit phagosome-lysosome fusion,
Sulfatides - cause prod H2SO4 when they hydrolyze, live w/in cell in their own soup of sulfuric acid, (-) lysosomal fusion
Listeria - how do they survive IC?
escape from phagosome into cytoplasm before lysosomal fusion
Obligate IC microbes?
Viruses, Chlamydia, Rickettsia, Coxiella
Syncytial viruses - how do they survive IC? ex/
paramyxo, herpes virus, HIV
Avoid humoral immunity by moving cell to cell using fusion of cell mem (move from infected cell and fuse to non infected cell - avoid time spent EC)
Herpes virus, adeno virus, rubeola - how do they survive IC?
dec expression of MHC on infected cells, (-) Tc
Key IgA protease producers
enter via mucosal surfaces
H. influ
S. pneumo
N. gon/menin
Which microbes have type III secretion systems? what is it?
A toxin injection device - family Enterobacteriaceae, Pseudomonas, Chlamydia
Which bact has Invasins, fxn?
Ex/ yersinia pseudotuberculosis
Invasins - surface prot that promote binding and penetration of non-phagocytic cells.
Fxn of siderophores?
many bact produce these to allow them to chelate iron for energy
Collagenase - ex/ of bact, use
Breaks peptide bonds in collagen - Clostridium perfringens
Hyaluronidase - ex of bact, fxn?
Breaks down hyaluronic acid - S. pyogenes, C perfringens
Lecithinase - bact? fxn?
disrupts cell mem lecithin, leading to myconecrosis
ex. Clostridium perfringens
Streptokinase - bact? fxn?
dissolves fibrin clot - S. pyogenes
Streptodornase - bact? fxn?
breaks down DNA rel by dead cells and dec viscosity of pus - allowing for much more rapid spread thru tissues
- Streptococcus
bact particles that (+) neutrophils
What is active component of LPS (endotoxin)? why can it not be converted into a toxoid?
Lipid A.
Endotoxins are heat stabile, can’t be conv to toxoid
Endotoxins are from which bact
G-
MoA of Endotoxin?
Bind to CD14 on mac and dendritic cells –> (+) overproduction of cytokines
In the case of Post strep GN - what type of HS? antibodies vs what?
HS-III
Immune complexes of Ab vs S. pyogenes serotypes M12 and M14, circulate w/ antigen and block small diam blood vessels
HS-IV - why do IC organisms cause this? ex/
IC organisms (-) cell mediated immunity
ex. TB, leprosy, Chlamydia PID
What is released on death of G+ bact? fxn?
peptidoglycan teichoic acid fragments, chemotactic for neutrophils
Why does Neisseria menin lead to such a rapid onset of endotoxin shock? sx?
Neisseria has an overproduction of outer membrane fragments –>petechial hemorrhage and ecchymoses of palate and skin from time of onset of malaise and fever.