Genetics and toxins Flashcards
1
Q
exotoxin coded where
A
plasmids and bacteriophages
2
Q
endotoxin coded where
A
bacterial chromosome
3
Q
antigenicity of exo and endo toxins
A
exotoxins very antigenic
endotoxins not antigenic
4
Q
heat stability of exo and endo toxins
A
exotoxins: stable up to 60 degrees Celsius except for staph enterotoxin
endotoxin: stable for 1 hr in 100 degrees
5
Q
examples of exotoxins
A
tetanus
botulism
diphtheria
6
Q
examples of endotoxin
A
meningococcemia
GN sepsis
7
Q
what are some things exotoxin can do (6)
A
- inhibit protein synthesis
- increase fluid secretion
- inhibit phagocytic activity
- inhibit release of NT
- lyse cell MB
- superantigens causing shock
8
Q
what organisms’ exotoxins inhibit protein synthesis? (4)
A
- Corynebacterium diphtheriae
- Pseudomonas aeruginosa
- Shigella spp
- EHEC 0157:H7
9
Q
Diphtheria toxin
- who secretes it
- action
- clinical manifestation
A
- corynebacterium diphtheriae.
- inactivates elongation factor (EF2) to inhibit protein synthesis
- pharyngitis w/pseudomembranes in th roat and severe LAD (bull neck)
10
Q
exotoxin A
- who secretes it
- action
- clinical manifestation
A
- pseudomonas
- inactivates elongation factor (EF2) to inhibit protein synthesis
- host cell death
11
Q
shiga toxin (ST)
- who secretes it
- action
- clinical manifestation
A
- Shigella spp
- inactivates 60S subunit by removing adenine from rRNA
- GI mucosal damage –> dysentry … potential HUS 2/2 cytokines
12
Q
shiga-like toxin (SLT)
- who secretes it
- action
- clinical manifestation
A
- EHEC
- inactivates 60S subunit by removing adenine from rRNA
- enhances cytokine release –> HUS … cannot invade host cells
13
Q
what organisms have exotoxins that can increase fluid secretion (3)
A
- ETEC
- vibrio cholera
- bacillus anthracis
14
Q
heat-labile toxin (LT)
- who secretes it
- action
- clinical manifestation
A
- ETEC
- increase cAMP –> increase Cl and H2O secretion in GI
- watery diarrhea
15
Q
heat-stable toxin (ST)
- who secretes it
- action
- clinical manifestation
A
- ETEC
- increase cGMP –> decrease resorption of NaCl and water in gut
- watery diarrhea
16
Q
cholera toxin
- who secretes it
- action
- clinical manifestation
A
- vibrio cholerae
- increases cAMP by permanent activation of Gs –> increase Cl and water excretion in GI
- voluminous “rice-water” diarrhea
17
Q
edema factor
- who secretes it
- action
- clinical manifestation
A
- bacillus anthracis
- mimics AC –> increases cAMP
- edmatous borders of black eschar in cutaneous anthrax
18
Q
what organism has exotoxin that inhibits phagocytic ability (1)
A
- bordetella pertussis
19
Q
pertussis toxin
- who secretes it
- action
- clinical manifestation
A
- bordetella pertussis
- increase cAMP by disabiling Gi –> impairs phagocytosis
- Whooping cough
20
Q
what organisms have exotoxins that inhibit release of NT (2)
A
- clostridium tetani
2. clostridium botulinum
21
Q
tetanospasmin
- who secretes it
- action
- clinical manifestation
A
- clostridium tetani
- protease that cleaves SNAREs that release GABA
- spasticity and lockjaw 2/2 inability relax
22
Q
botulinum toxin
- who secretes it
- action
- clinical manifestation
A
- clostridium botulinum
- protease that cleaves SNAREs that release Ach
- flaccid paralysis
23
Q
what organisms have exotoxins that lyse cell MBs? (2)
A
- clostridium perfringens
2. strep pyogenes
24
Q
alpha toxin
- who secretes it
- action
- clinical manifestation
A
- clostridium perfringens
- phospholipase (lecithinase) that degrades tissue and cell MB
- PL degradation –> myonecrosis (gas gangrene) and hemolysis (“double zone” of hemolysis on blood agar)
25
streptolysin O
- who secretes it
- action
- clinical manifestation
- strep pyogenes
- protein that degrades cell MB
- lyses RBCs --> beta-hemolysis
ASO titers used to dx rheumatic fever
26
what organisms have exotoxins that cause shock (2)
1. staph aureus
| 2. strep pyogenes
27
toxic shock syndrome toxin (TSST-1)
- who secretes it
- action
- clinical manifestation
- staph aureus
- recruits MHC-II and TCR to cause overwhelming release of IFN-gamma and IL-2 --> shock
- fever, rash, shock
28
exotoxin A
- who secretes it
- action
- clinical manifestation
- strep pyogenes
- recruits MHC-II and TCR to cause overwhelming release of IGN-gamma and IL-2 --> shock
- fever, rash, shock
29
some consequences of endotoxin (9)
ENDOTOXIN
```
Edema
Nitric oxide
DIC / Death
On outer MB
TNF-alpha
O-antigen
Xtremely heat stable
IL-1
Neutrophil chemotaxis
```
30
what three things does lipid A of endotoxin activate?
1. activates macrophages
2. activates copmlement
3. activates TF
31
consequences of LPS activating macrophages? (3)
1. IL-1 --> fever
2. TNF --> fever and hypotension
3. NO --> hypotension
32
consequences of LPS activating TF? (1)
1. coagulation cascade --> DIC
33
consequences of LPS activating complement? (2)
1. C3a --> hypotension and edema
| 2. C5a --> neutrophil chemotaxis
34
what is bacterial transformation?
taking up naked DNA from environment after cell lysis
35
which organisms are better known for ability for transformation (3)
SHiN
strep pneumo
h flu
neisseira
36
conjugation partners
F+ : has plasmid for genes of pilus and conjugation
| F- the receiver
37
what's trasnferred in conjugation
just plasmid DNA, not actual bacterial chromosomal genes
38
what's transposition
where transposon (DNA segment) can jump from one location to another (b/w plasmid and genome etc)
39
what are the two types of transductions?
1. generalized
| 2. specialized
40
what's generalized transduction
"packaging event"
lytic phage infects bacterium, cleaves bacterial DNA and parts of bacterial DNA packaged in viral capsid
phage will then infect next cell and transfer genes
41
what's specialized transudction
"excision event"
lysogenic phage infects bacterium
viral DNA goes into bacterial DNA and excises out the flanking bacterial genes
42
genes for which toxins are coded on lysogenic phages? (5)
1. ShigA-like toxin
2. Botulinum toxin
3. Cholera toxin
4. Diphtheria toxin
5. Erythrogenic toxin of strep pyogenes
