Microbial Virulence Flashcards
Kocks postulates
Causative relationship between microbe and disease
Attenuation
Decrease/loss of virulence of a pathogen
CD66 —> Pili
N.gonorrhoeae + Opa protein
Which gram contains filamentous proteins
Negative
What grows only in calf placenta? And why?
Brucella abortus
Erythritol
How much iron does bacteria need in a day?
0.4-40 uM
How much iron is available in the plasma?
10^-18 uM
Where is the majority of iron stored?
Haem / ferritin / haemosidern
Low levels of iron are associated with what?
Increased exotoxin production
Borrelia burgdoferi
Substitutes iron for manganse for its metal ion enzymes
Haem oxygenase
Extract iron
Sidephore
E.coli
Aerobactin acts upon transferrin
10^50
Transferrin
10^36
Hyaluronidase
Polysaccharide hyaluronic acid breakdown
Found in host cells
Strpetokinase
Break down fibrin clots
Pathogenic spread
Coagulase
Promotes clotting
S.aureus
Where are enterotoxin genes found?
Plasmids
Name 3 exotoxin categories
AB
Cytolytic
Super antigen toxins
Lecithinase
Cell lysis on Lecithin
Clostridium perfringins
Cytolytic toxin
Staphylococcal a-toxin
Integrate into phosholipid
Oligomerize into lytic hepatamers
Undergo changes to produce membrane pores
AB toxin inhibits what?
Protein synthesis
Fragment B (AB)
Binds to host cell receptor
Fragment A (AB)
Disrupts protein synthesis
How are A - B bound?
Covalent bond /disulphide bond
Diphtheria toxin
C.diphtheriale
Encoded by bacteriophage B
- Stage of Diptheria toxin
B- Binds irreversibly to host HB-EGF
Epithelial surfaces nose /throat
2.stage diptheria toxin
Cell uptakes toxin by endocytosis
3.stage of diptheria toxin
Cleavage of A / B (disulphide bond)
A + ADP-ribosylates EF-2
Stopping protein synthesis
Symptoms of diptheria toxin
Myocarditis
Neuritis
Tetanus
Clostridium tetani
Where does clostridium tetani germinate?
Enters in break of skin
Germinates in anoxic area
Where is clostridium tetani found?
Endospore forming bacteria in soil
Tetanospasmin binds to what?
Ganglioside lipids on termini of inhibitory interneurons
Tetanospasmin has prevents release of what?
GABA (neurotransmitter)
AcH constantly released
Uncontrolled contractions
Backward arching of neck caused by tetanospasmin
Opisthotonus
Name a spastic paralysis causing toxin
Tetanospasmin
Name a flaccid paralysis toxin
Botulium
Type A / B /E/F C.botulium
Cause disease in humans
Type H C.botulium
2ng causes death
Very very potent
Botulium toxin structure
150kDa
Light /heavy chain
Botulium toxin binds to what
Bioactive protein complex (BPC) binds to presynaptic termini at neuromuscular junction
How does Botulium toxin stop AcH release?
Cleaves SNARE /SNAP proteins
Prevents muscle contraction as no excitatory AcH can bind to its ligand
How is cholera transmitted? What route?
What produces the toxin?
Faecal oral route
Vivrio cholerae produces Choleragen
How many B units are in Choleragen?
How many A units?
5B
1 A unit (A1/A2)
B unit Choleragen binds to what? What does it allow?
B unit —> GM1
Allows A to penetrate cell
A subunit from Choleragen binds to what?
What does it add from NAD?
Targets GTP
Adds ADP-Ribose (ADPR) from NAD
to AC-Gs
AC-Gs-ADPR = what?
Increasing cAMP
Change in flux sodium/chloride
Cells lose water to gut lumen
20L secretion
