Microbiology: Tuberculosis, Leprosy, Etc

Front 1

Langhan's cells

Back 1

Langhans giant cells are large cells found in granulomatous conditions.

They are formed by the fusion of epithelioid cells (macrophages), and contain nuclei arranged in a horseshoe-shaped pattern in the cell periphery.

Their presence could indicate tuberculosis or other mycobacterial infection.

Front 2

Crohn's disease, or chronic granulomatous enteritis causative pathogen?

Back 2

M. avium paratuberculosis

Front 3

Lady Windermere syndrome

Back 3

Elderly non-smoking women who suppress their cough
modular bronchiectasis
MAC, M abscessus

Front 4

Middle aged male smokers?

Back 4

apical cavitary disease
MAC, M. kansasii

Front 5

Lepromatous leprosy: for DX lepromin?

Back 5

No. These pts are anergic to lepromin

Front 6

DX of TB

Back 6

PPD
gamma interferon

Front 7

IF PPD positive and larger than 20 mm, but after a BCG, what is the next DX step?

Back 7

gamma interferon test is not affected by BCG

Front 8

Describe TB pathogenesis and immunity from the beginning
Macrophages, T cells, etc

Back 8

Infects macrophages, prevents fusion of the phagosome with the lysosome, macrophages secrete IL 12 and TNF alfa. Now T1 differentiate and release gamma interferon which activates the macrophages to upgrade the lysosomal fusion and start killing.
TNF alfa stimulates production of nitric oxideand reactive nitrogen intermediates.

Front 9

Instead of O antigen LPS, mycobacteria have what?

Back 9

LAM (lipoarabinomannan)

Front 10

Describe major biochemical/morphological aspects of Mycobacteria

Back 10

weakly G+, non motile, aerobic, intracellular, if anaerobic then latent, strong reducers of nitrates, catalase positive, slow-growing, most, rods, with sometimes beaded appearance, do not form spores

Front 11

Myc. t. generation time and visible on colonies

Back 11

generation time 12 to 24 h
visible colonies in 2-4 weeks

Front 12

Is TB sensitive to UV and heat?

Back 12

YES

Front 13

At what temperature does TB grow?

Back 13

37 C and no growth at room temperature

Front 14

What percentage of the infected have a negative PPD test?

Back 14

15%

Front 15

HOw does TB enter cells?

Back 15

Fc receptors
compliment
or LAM terminal mannose interaction with mannose receptors on macrophages

Front 16

What components inhibit oxidative killing? (TB)

Back 16

LAM, glycolipids and sulfatides

Front 17

How does TB produce immunosuppression

Back 17

It produces TGF beta which suppresses immune response

Front 18

Describe outcomes after TB exposure

Back 18

After exposure:
30% become PPD positive
70% kill it immediately

of the 30% that became PPD +, 10% develop the disease, 90% stay PPD +,
Of the 90% that are PPD +, 5% develop disease, if with HIV every year +10% risk

Front 19

What this dose of infective particules of TB needed for infection

Back 19

1-3 bacilli in a 5 micrometer diameter particle

Front 20

Simon foci

Back 20

calcified milliary lesions (1-3 mm)

Front 21

TB: primary lesion location

Back 21

apex of lungs in adults
mid to lower lung in children

Front 22

reactivation is commonly located where in the lu ng

Back 22

apex

Front 23

Most symptoms of TB are due to the overproduction of what chemical?

Back 23

TNF

Front 24

Describe the course of TB meningitis

Back 24

intermittent or persistent fevers for 2-3 weeks
HA
progressive subtle mental status changes
low glucose, high protein in CSF
Fever- low grade or absent

Front 25

Sites of POtt's disease

Back 25

lumbar or thoracic vertebra>knee/hip>ankle>elbow>wrist>shoulder

Front 26

Mantoux: what makes it positive and in what cases

Back 26

read after 24-48 hours
do not scratch
positivity is with induration
with just erythema, it's not positive
+if more than 5mm for pts in contact with recently diagnosed, HIV pts, pts on prednisone 15mg/day for more than a month, pts with organ transplant
+if more than 10mm for pts with conditions that increase tb risk, recent converters from 10 to more than 10, recent immigrants, kids <4 exposed to adults at high risk to tb

Front 27

List what samples we can obtain to look for tb

Back 27

sputum samples for 3 consecutive days
bone marrow biopsy
sputum induction for suspected subpleural tb
for kids and adults unable to produce sputum, early morning gastric aspirate

Front 28

Should we obtain HIV serology in TB patients?

Back 28

YES

Front 29

TX for infection with no clinical disease (TB)

Back 29

Isoniazid for 6 to 12 months

Front 30

TX for clinical TB

Back 30

isoniazid, rifampin, ethambutol, pyrazinamide daily for 2 months followed by inh plus rifampin for 4 months

Front 31

TB tx for pregnant women

Back 31

vit B6, isoniazid, ethambutol, rifampin

Front 32

What is TB relapse rate?

Back 32

0-4%

Front 33

How effective is BCG in children

Back 33

60-80%

Front 34

What vitamin enhances immunity to TB

Back 34

Vitamin D