Bacteriology II

Question 1

What are the general characteristics of atypical bacteria? (6)

Answer 1

1. Difficult to culture
2. Unusual cell wall/absence of cell wall
3. Specific/unusual cellular staining properties
4. Usually small size
5. Most replicate intracellularly
6. Slow growth

Question 2

What are common clinical examples of atypical bacteria?

Answer 2

1. Mycobacterium tuberculosis
2. Chlamydia
3. Mycoplasma

Question 3

The growth speed of mycobacteria is generally [higher/lower] than that of other bacteria

Answer 3

(Much) lower

Question 4

What makes mycobacteria difficult to stain?

Answer 4

Specialized cell wall with a waxy lipid layer

Question 5

What is the advantage of the specialized cell wall to mycobacteria?

Answer 5

They are resistant to killing by phagocytes

Question 6

What is a common comorbidity found in TB patients?

Answer 6

HIV

Question 7

How many cases of TB are cleared by the innate immune system?

Answer 7

~70%

Question 8

What happens when TB infections are not cleared by the innate immune system?

Answer 8

Formation of a Ghon complex -> granulomatous inflammation encasing the infection site

Question 9

Where does the majority of TB-associated granulomas occur?

Answer 9

Lungs

Question 10

How many % of TB infections become latent?

Answer 10

~10%

Question 11

How many of the granulomatous laesions TB will break down? What happens if they do?

Answer 11

1-3% of granulomas (=0,3-1% of all TB infections) will break down, resulting in dissemination of TB through the body

Question 12

How many % of TB cases immediately disseminate?

Answer 12

~3%

Question 13

What causes reactivation of latent TB?

Answer 13

Impairment of the cellular immune system due to various stressors (stress, malnutrition, malignancy, HIV, old age, immunosuppression, diabetes, etc.)

Question 14

What are two important virulence factors of Mycobacterium tuberculosis?

Answer 14

1. Nuog-gene
2. hip1-gene

Question 15

What does the nuog gene of TB do? (2)

Answer 15

1. Delays migration of DCs to the lungs
2. Inhibits apoptosis of infected neutrophils

Question 16

What does the hip1 gene of TB do? (3)

Answer 16

1. Inhibits inflammasome-dependent macrophage proinflammatory responses
2. Impairs CD40-mediated costimulatory responses of DCs
3. Restricts Th17 polarization during infection

Question 17

What is the treatment of tuberculosis? How long does this treatment have to be given?

Answer 17

Antibiotics, usually 2 months intensive + 4 months continuation

Question 18

Which compounds are the current first line treatment for TB? (2)

Answer 18

1. Rifampicin
2. Isonazid

Question 19

What are the 3 main factors contributing to TB drug resistance?

Answer 19

1. Not completing the complete treatment regimen
2. Pharmacokinetic population variablity (=dosage too low)
3. Granuloma variation (size, composition, etc.)

Question 20

What is the TB vaccine? What is it based on?

Answer 20

BCG, derived from live Mycobacterium bovis

Question 21

What is the disadvantage of the BCG vaccination?

Answer 21

May hide infection when testing for TB

Question 22

Which chlamydia species form a danger to humans?

Answer 22

1. C. trachomatis
2. C. pneumoniae
3. C. pstittaci

Question 23

What is C. psittaci associated with?

Answer 23

Birds, mainly parrots

Question 24

What are the general characteristics of Chlamydia bacteria? (4)

Answer 24

1. Obligate intracellular parasitic bacteria
2. Gram-
3. Cannot synthesize ATP -> requires host ATP
4. Unique biphasic life cycle

Question 25

What are the two phases in the biphasic life cycle of chlamydia?

Answer 25

1. Elementary bodies -> resistant to harsh environmental conditions 2. Reticulate bodies -> non-infectious, intracellularly replicating form

Question 26

Which two biological variants of Chlamydia trachomatis can be distinguished? Which cell types do they infect?

Answer 26

1. Trachoma -> eye and urogenital epithelial cells 2. Lymphogranuloma venereum -> macrophages

Question 27

Which of the two biological variants of Chlamydia trachomatis can lead to invasive tissue infections?

Answer 27

Lymphogranuloma venereum

Question 28

What is a major complication of chronic/recurrent C. trachomatis eye infections?

Answer 28

Blindness (leading preventable cause of blindness worldwide)

Question 29

Where are eye infections with C. trachomatis often found?

Answer 29

Children in rural areas of Africa

Question 30

How are eye infections of C. trachomatis spread? (2)

Answer 30

1. Discharge from the eyes 2. Flies

Question 31

Where are lymphogranuloma venereum infections often found?

Answer 31

Genital area

Question 32

What is the disadvantage of lymphogranuloma venereum infections?

Answer 32

They are often asymptomatic -> high transmission

Question 33

What are complications of lymphogranuloma venereum? (3)

Answer 33

1. Ectopic pregnancy 2. Pelvic inflammatory disease (PID) 3. Sterility

Question 34

Which bacterium is frequently found in co-infection with lymphogranuloma venereum?

Answer 34

N. gonorrhoea