Toxins

Question 1

Diphtheriae

type

Answer 1

GPR
- looks like caligraphy in gram stain

Alert the lab about possible diphtheria

Major virulence is diphtheria toxin

Question 2

What does the diphtheriae toxin attack?

Answer 2

The heart
Peripheral nerves
Kidneys
- Diph organism itself does not invade beyond the upper resp tract or skin

It inhibits protein synthesis by modifying EF-2 in eukaryotic cells which is required for protein synthesis
(modified EF-2 in euk cells cannot fxn in protein synth)
- The A-subunit of DT catalyzes the transfer of the ADP ribose part of NAD onto EF-2 in the cytoplasm of all euk cells.

Question 3

What can you look for in your blood to show that you are protected against diph?

Answer 3

anti-toxin in your blood

• can test via immunoprecipitation and PCR detection of tox gene

Question 4

How is diphtheria toxin taken up in susceptible cells?

Answer 4

by receptor mediated endocytosis

• not all cells have it
• inhibiting protein synth in euk cell –> it dies

Question 5

What is required for expression of diph toxin?

Answer 5

a bacteriophage and low iron

• tox gene is on the bacteriophage –> phage conversion
• Gene for Iron (dependent repressor (DtxR) is on chromosome
  (high iron induces repression of toxin production)

Question 6

Why do you have to report cases of Diphtheria?

Answer 6

Report to CDC - only place that antitoxin can be obtained
- tx is basted on clinical dx and hx of travel to endemic areas and hx of vaccination

• AB are not used as a primary tx for diphtheria!

Question 7

When do you use Ab to treat diphtheria?

Answer 7

AB are not used as a primary tx for diphtheria! They do no treat diphtheria.

Azithromycin can be used to prevent carriage of bacteria and spread and possible contacts

Question 8

Gold std for dx pertussis?

Answer 8

Stic, swab up nose–> make them cough
Grow on Regan Lowe media for 3-4 days

*can also PCR but its 4x the cost of culture

Question 9

B pertussis adheres very tightly to what?

Answer 9

Ciliated respiratory epithelial cells

Question 10

is toxin testing done for pertussis?

Answer 10

Nope, just diphtheria

Question 11

Paroxysmal stage of whooping cough.

Whats interesting about it?

Answer 11

Culture goes way down, but WBC lymphs go way up.

- rarely do you see rise of lymphocytes with bacteria infxn. Suspect pertussis