Mycobacteium Tuberculosis

Question 1

Mycobacterium

Answer 1

Filamentous
Aerobic
Non-sporulating
Bacilli
“Beaded gram positive rods”
High mycolic acid content in the cell wall (resistance to detergent, antibiotics)
Acid fast
Slower growth

Question 2

Mycobacterium tuberculosis complex (MTb)

Answer 2

Comprised of M tuberculosis and seven closely related species (M bovis, M africanum, M microti, M pinnipedii, M canetti, M mungi, M caprae
Transmission is person to person

Question 3

M bovis

Answer 3

Transmitted to human from infected cows or contaminated milk
Pyrazinimide resistant
M bovis bacillus Calmette-Guerin (BCG) is a strain used as a vaccine for TB

Question 4

Tuberculosis

Answer 4

Caused by mycobacterium tuberculosis
Human to human spread
Bacilli are transmitted an infectious aerosols produced by coughing talking or singing
Risk of infection depends on bacterial load, exposure time, and environmental factors

Question 5

MTb pathogenesis

Answer 5

Watch is an alveoli and is engulfed by macrophages
Prevents fusion of phago lysosome
Attracts monocytes and lymphocytes
Developes granule a (dependent on CD4 T cell and TNF)
Causes caseous necrosis
Infected macrophages carried to lymph nodes

Question 6

MTb is a type _ hypersensitivity reaction that can be measured using

Answer 6

IV
TST/PPD or IGRA

Question 7

Risk factors for Tb infection

Answer 7

Exposure to TB case
from TB endemic area
homeless
incarcerated
work in healthcare

Question 8

Tb with symptoms=

Answer 8

Active TB disease

Question 9

TB infection without symptoms=

Answer 9

Latent TB

Question 10

TB risk for deactivation

Answer 10

Recently infected
Children <5
Immunosuppressed (HIV, TNF inhibitor, leukemia, diabetes, end stage renal disease)
Malnourished
smokers
alcoholics

Question 11

Symptoms of TB

Answer 11

Pulmonary disease
Prolonged cough, hemoptysis, chest pain, weight loss, loss of appetite, night sweats, fever, fatigue, upper lung lesions, pleural infection
Extrapulmonary disease (meningitis, tuberculoma, lymph node enlargement
Bone infection (spine)
Genitourinary
Peritoneal
Disseminated

Question 12

Diagnosis of symptomatic TB infection

Answer 12

AFB smear
AFB culture
molecular assay

Question 13

Diagnosis of asymptomatic TB infection

Answer 13

Immune Assay-PPD/TST test, interferon gamma release assays

Question 14

_ staining of TB can be performed

Answer 14

Acid fast using Ziehl-Nielsen
Requires high bacterial burden
Cannot distinguish between Mycobacterium species

Question 15

_ is the gold standard for TB diagnosis

Answer 15

Culture
MGIT or solid media (requires weeks)

Question 16

Molecular detection of TB

Answer 16

Rapid
Specific
Fastest way to rule out infectious TB

Question 17

Latent TB diagnosis

Answer 17

tuberculin hypersensitivity (requires effect of CD4 TH1 cells, IL-12, INF gamma, TNF)
Tuberculin skin testing and IGRA

Question 18

IGRA

Answer 18

better specificity for detecting TB (fewer false positives
Does not rule out active TB

Question 19

Treatment of latent TB

Answer 19

Prevent development of active disease
Rifampin + INH

Question 20

Treatment of active TB

Answer 20

4 drug therapy (RIPE)
Rifampin, Isoniazid, Pyrainamide, Ethambutol

Question 21

Drug resistance TB

Answer 21

Resistant to 1 in 4 first line antibiotics

Question 22

MDR TB

Answer 22

Resistant to 2 of 4 first line antibiotics

Question 23

XDR TB

Answer 23

Resistant to at least 1 of 3 second line antibiotics

Question 24

Multi drug resistant TB

Answer 24

Risk associated with exposure to MDR-TB, residence in high risk area, failure to respond to therapy
Treat with multiple agents
High toxicity and high mortality

Question 25

Prevent TB by

Answer 25

Treating those infected
Testing these who meet exposure definition