Diseases of Respiratory System - Mycobacterial Diseases (20)

Question 1

Mycobacteria

Answer 1

Slender bacillus

Question 2

How is mycobacteria different to all other bacterial genera?

Answer 2

Unusual waxy cell wall (high lipid content) and slow growing (different media requirements)

Question 3

Mycobacteria and stains

Answer 3

Gram +ve outer cell wall (ghost cells - stain badly), retain certain stains without decolorisation by acid/alcohol (‘acid fast bacilli’ AFBs - Ziehl Neelsen and Phenol auramine)

Question 4

Why can’t macrophages digest mycobacteria?

Answer 4

Intra-cellular

Question 5

Slow growth of mycobacteria means that

Answer 5

You can have latent phase of infection/chronic - dormant

Question 6

Treatment of mycobacteria

Answer 6

Different antimicrobial agents, much longer, combination to prevent resistance

Question 7

Mycobacteria. TB examples

Answer 7

M. TB and M.Bovis > TB

Question 8

Mycobacterium. leprae

Answer 8

Causes leprosy

Question 9

‘Atypical Mycobacteria’

Answer 9

M. avian complex (HIV associated), M.kansasii (presents similar to TB), M.marinum (Fish tank granuloma)

Question 10

Epidemiology M.TB

Answer 10

1/3rd population infected, 2 million deaths per year, commonest infectious cause adult deaths, co-infection with HIV (sub-saharan africa)