L4. Bacterial pathogenesis: virulence factors and toxins

Question 1

define pathogenicity islands

Answer 1

virulence genes (tend to be clustered together in “islands”)

Question 2

define adhesins?

Answer 2

allow bacteria to stick onto something (ex commensal bacteria that move to different location like E coli in urinary tract)

Question 3

where do N gonorrhea, e coli and campylobacter stick?

where does bordetella pertusis stick and what does it cause?

Answer 3

N gonorrhea (pili) - cervical and buccal cells

E coli and campylobacter - intestinal walls

bordetella pertusis - ciliated resp cells and whooping cough

Question 4

what are capsules also known as (2)?

Answer 4

slime layer or glycocalyx

Question 5

what is special about streptococcus mutans?

Answer 5

Can stick to tooth enamel using its dextran and levan capsule

Question 6

pseudomonas, s aureus have the ability to do wht?

Answer 6

form biofilms

Question 7

define quorum?

Answer 7

minimum number of bacteria required to make a biofilm

Question 8

what is a colony of bacteria?

Answer 8

group of bacteria that are genetically identical

Question 9

what is an autoclave used for?

Answer 9

high temperature an pressure applied within this instrument that kill even endospores!

Question 10

biofilms infection examples? (4)

Answer 10

Valve endocarditis
Periodontitis
Cystic fibrosis
Otitis media

Question 11

what are leukocidins and where are they found?

Answer 11

pore forming, degranulation of lysosomes within leukocyte

“Leukas Steps in New NEEES Helicopter”
strep pneumonia, Nesisseria, h. influenza

Question 12

What are porins and where are they found?

Answer 12

inhibit phagocytosis by activating adenylate cyclase

STAP STEPing in New Pores!!!!!
staph, strep, pneumococci

Question 13

what is protein A and where is it found?

Answer 13

prevents complement interaction w/ antibodies

Staph Aureus

Question 14

define hemolysins?

Answer 14

produced by streptococci; ability to break down red blood cells

apparently even E coli and some staph produce this

Question 15

define different types of hemolysins? (3)

Answer 15

beta, alpha and gamma

Question 16

streptokinase?

Answer 16

produced by strep, used to treat blood clots in heart!

Question 17

staphylokinase?

Answer 17

same as strep; dissolve blood clots

Question 18

facultative intracellular organisms survive inside cells how?

Answer 18

inhibit phagosome - lysosome fusion

listeria, salmonella, yersinia, fancisella, brucella, mycobacterium, legionella and nocardia

Question 19

cytotoxins?

Answer 19

kill cells

Question 20

endotoxins?

Answer 20

LPS

Question 21

what is the only gram positive bacteria that can produce endotoxins?

Answer 21

listeria

Question 22

endotoxins heat stability?

Answer 22

very stable vs exotoxins which are heat unstable (b/c proteins)

Question 23

endotoxins fever abilitity?

Answer 23

yes! (exotoxins don’t)

Question 24

endo vs exotoxin lethal dose?

Answer 24

endo - large (less toxic)

exo- small (more toxic)

Question 25

how do endotoxins cause fever?

hypotension?

fever and hypotension?

hypotension and edema?

Answer 25

fever - IL - 1

hypotension - nitric oxide

hypotension and fever - TNF

hypotension and edema - C3a

Question 26

imp how do endotoxins cause coagulation?

Answer 26

through activating tissue factors!

Question 27

what is cholera toxin mechanism?

Answer 27

increases cAMP levels to cause loss of water

Question 28

A-B toxins method of action?

Answer 28

A is for action (catalytic domain)

B is for binding (receptor bidning domain)

Question 29

A-B toxins?

Answer 29

exotoxins - gram positive

Question 30

what is the diphtheria toxin mechanism?

Answer 30

A-B toxin that interferes with protein synthesis

• transfers a group (ADP - ribose from NAD molecule) to elongation factor -> no longer functional
• tRNA will no longer do translocation of mRNA

Question 31

what is the botulism toxin mechanism?

Answer 31

one of the most poisonous substances known

• breaks down snare proteins -> prevents docking of vesicle on membrane -> inhibits release of ACh
• causes paralysis!

Question 32

what is the clostridium perfringens toxin mechanism?

Answer 32

cause food poisoning

• produce buteric acid -> smelly
• produce gas gangrene (by alpha toxin) causes tissue necrosis
• produce enterotoxin during spore formation!

Question 33

what is the anthrax toxin mechanism?

Answer 33

cutaneous, pulmonary and intestinal types

• pXO1: protective antigen (forms pore to allow other 2 to get in), edema and lethal factor
• pXO2: forms the capsule/cell membrane

Question 34

what does the edema factor do?

Answer 34

adenylate cyclase

• increase cAMP, loss of Chlorine, edema in tissue

Question 35

what does lethal factor do?

Answer 35

cleaves phosphokinases

• which stops cell growth

Question 36

what does protective antigen do?

Answer 36

forms pores in cell membrane

• to facilitate EF and LF entry

Question 37

what does tetanus toxin do?

Answer 37

toxin: tetanospasmin

- dampen down the inhibitory NT response (ex LOCKJAW)

Question 38

endotoxin vs exotoxin antigenicity?

Answer 38

exotoxin has higher antigenicity!!