Case 44: Screening of contacts of a man with gonorrhoea

Question 1

What is the Gram stain for Chlamydia trachomatis?

Answer 1

Gram -ve

Question 2

Why won’t Chlamydia be seen on a Gram stain?

Answer 2

Because it doesn’t have a cell wall

Question 3

What type of a bacteria is Chlamydia trachomatis?

Answer 3

Obligate intracellular bacteria

Question 4

What are the 2 forms that Chlamydia exists in?

Answer 4

Elementary body - infectious, non-replicating, hardy

Reticulate body - intracellular, replicating form

Question 5

Why is Chlamydia trachomatis an “energy parasite”?

Answer 5

Because it cannot produce metabolites and many cannot produce net energy and require host cell ATP

Question 6

How does Chlamydiae enter the host cell?

Answer 6

EB entry into mucosal epithelium by adhesins and receptor mediated endocytosis

Question 7

How does Chlamydiae multiply in the host cell?

Answer 7

EB incorporated into endosome (endosome retains pH>6.5, doesn’t fuse with lysosome, so no destruction).

EB becomes metabolically active RB (vesicle contrains 200-1000 organisms)

RB converted to EB

Question 8

How does Chlamydiae spread from the host cell?

Answer 8

Released as elementary bodies

Question 9

Which form of Chlamydia is susceptible to therapy?

Answer 9

Reticulate bodies

Question 10

What is used to treat chlamydia?

Answer 10

Multi-dose tetracycline or erythromycin

or

Single dose azithromycin

Question 11

What does a Gram stain for N. gonorrhoea show?

Answer 11

Gram -ve diplococci

Question 12

How are N. gonorrhoea infections treated?

Answer 12

Cephalosporins and fluoroquinolones

Question 13

What does a Gram stain for treponema pallidum show?

Answer 13

Gram negative spirals