block 4- toxaemia

Question 1

diphtheria

Answer 1

-respiratory transmission
-ore throat and fever
-difficulty swallowing, irregular heartbeat,coma
-characteristic = pseudomembranes in throat(greyish in the throat= combination of dead cells)

Question 2

the causative agent of Diphtheria

Answer 2

-actinobacteria= same phylum as mycobacterium
-bacteria is only found in the throat but damage occurs to the heart and kidney this is because it secretes a toxic protein that circulates in the blood
-injection of the toxin can cause the disease
-blood of an immunized animal can cure disease

Question 3

diphtheria toxin and vaccination

Answer 3

• because the disease is mainly caused by the toxin and antibody against the toxin is enough to prevent disease
  -since the toxin is a protein it can be made safe by denaturing it to make a (toxoid)= denatured protein
  -

Question 4

treating diphtheria in unvaccinated patients

Answer 4

• an antibiotic (penicillin or erythromycin) will kill the bacteria in the throat so prevents transmission and cures infection
  -antitoxin (antibody that blocks toxin is needed to protect the heart and other organs
  -both are needed

Question 5

bacterial exotoxins

Answer 5

-proteins made/secreted by bacteria that have toxic effects on other cells

Question 6

dipheria toxin

Answer 6

-an enzyme that modifies elongation Factor Tu,blocking translation
- example of a A-B toxin
-

Question 7

mechanism of dipheria toxin

Answer 7

-receptor binding
-endocytosis
-
finish in a sc

Question 8

what advantages does bacteria have by producing a toxin

Answer 8

-many toxins are virulence factors so may kill cells e.g. immune cells and release nutrients

Question 9

Clostridium tetani

Answer 9

-gram-positive, rod-shaped bacteria
-opportunistic pathogens
- causes muscle paralysis
-can infect wounds
-produces toxin gthnat targets neuron es = muscle spasms
- toxin targets cental nerves

Question 10

treatment of c.tetani(tetanus
)

Answer 10

-antitoxin antibody (stops more damage)
-antimicrobial e.g. penicillin
-breathing support while nerve endings regrow
-sometimes surgery on the wound

Question 11

c. botulium

Answer 11

spores germinate in food and bacteria produces the toxin
-if the person eats the food with the toxin without heating it up properly as heat kills the toxin then they would absorb the toxin via the intestine and targbetsz neurones
-causes flaccid paralysis (kind of like flimsy limbs)
-toxin targets periphetal nerves

Question 12

toxamia

Answer 12

• a disease where symptoms are entirely due to the toxin

Question 14

bordetella pertussis

Answer 14

• an obligate human pathogen (must infect host to survive and reproduce)
  -does not produce acid for sugars
  -produces 4 toxins

Question 15

filamentous haemagglutinin (FHA)

Answer 15

-a virulence factor
-. Processing

Starts as a 367 kDa precursor protein.
Processed into a 230 kDa mature protein.
Functional part is 60% of the precursor (N-terminal).
2. Structure
Filamentous: 2 nm wide, 50 nm long.
3. Function
Key for B. pertussis adherence to respiratory cells.
Helps bacteria attach to ciliated cells in the trachea.
4. Binding Targets
Recognizes glycolipids, proteoglycans, and integrins on host cells.

Question 16

FHA structure

Answer 16

Binding to Sulfated Sugars
Spanning residues bind to sulfated sugars on mucus-secreting epithelial cells.
RGD Tripeptide
The Arg-Gly-Asp (RGD) sequence binds to CR3 integrins on macrophages and ciliated cells.
Carbohydrate Recognition Domain (CRD)
The CRD binds to lactosyl ceramides on macrophages and ciliated cells.

Question 17

pertussis toxin

Answer 17

-it catalyses ADP-ribosylation of heterotrimeric G proteins= blocks several signalling mechanisms
-has two types of subunits
-A= enzymatic activity
-B- receptor binding part
-its important for colonization and establishment of infections

Question 18

what does pertussin toxin do?

Answer 18

• causes lymphocytosis (increased number of lymphocytes) increased release of insulin = less glucose=hypoglycemia
  -impairs neutrophil chemptaxis,phagocytosis and enhances respiratory tract
  -prevents movement of cilla
  colinisation = cells cannot kill pathogen or impaired function to kill pathogen

Question 19

tracheal cytotoxin

Answer 19

-fragment of peptioglycan
-lytic transglycoylases= cleaves peptioglycan= releases the toxin
-it causes stasis and death of cilliated epithelial cell

Question 20

are exotoxins always proteins

Answer 20

-mostly but no e.g. tracheal cytotoxin

Question 21

adenylate cyclase toxin

Answer 21

-converts Atp to cAMP and increases cAMP levels=inhibits immune effec tor cells by intoxicating macrophages and neutophils therefore cAMP = virulence factor
-secreted by bacteria and oftem remains attched
-inserts into cell membranes of eukaryotic cells
-can cause histamine sensitisation

Question 22

dermonecrotic toxin

Answer 22

-cell differecfauses modification of GTP-ases receptors e.g. polyamination or deamidation
-results in distruption of cytokinesis,cell differintation, gene expression etc…
-results in damage of tissues

Question 23

BvgAS two component system

Answer 23

• BvgS: Sensor protein (histidine kinase), detects Mg²⁺ and SO₄²⁻.
  BvgA: Response regulator, turns specific genes on/off. via phosphorlation hence why its a kinase
  Function: Helps bacteria adapt to the environment by regulating virulence genes.

Question 24

whooping cough-pertussis

Answer 24

Stage 1 - Colonization: Bacteria present; treatable with antibiotics; key virulence factors are FHA and pertussis toxin.
Stage 2 - Toxemic Phase: No bacteria, symptoms from toxins; antibiotics ineffective; key virulence factors are tracheal cytotoxin, adenylate cyclase toxin, dermonecrotic toxin.

Question 25

whooping cough- symptomatic stages

Answer 25

Stage 1: Catarrhal
Symptoms: Nonspecific, similar to a cold or viral infection.
Duration: Lasts 1-2 weeks.
Communicability: Highly contagious during this stage.
Stage 2: Paroxysmal
Symptoms: Severe, repetitive coughing with a characteristic “whoop” sound.
Duration: Lasts 1-4 weeks.
Stage 3: Convalescent
Symptoms: Reduced frequency and severity of coughing spells.
Duration: Complete recovery may take weeks to months.

Question 26

diagnosis of bordetella infections

Answer 26

-characteristic cough and clinical pictures
-cultured-based methods= Regar lowe agar containing nicotinic acid(because the bacteria can not make this)
-PCR or serology

Question 27

trasmission of whooping cough disease

Answer 27

-highly infectious with 90% efficiency
-infants a\nd young children especially those who haven’t been immunised
-major cause of childhood mortality

Question 28

prevention of whopping cough

Answer 28

-pertussis vaccines to everyone
-especially in pregnant women