Lecture 10: Mycobacteria

Question 1

For how many years has TB been a major human disease?

Answer 1

5,000 years

Question 2

Eradication of TB seemed possible until the emergence of which disease?

Answer 2

AIDS

Question 3

Which strains of TB are worst for public health?

Answer 3

MDR

XDR

Question 4

What effect does the slow-growing nature of mycobacteria have on medicine?

Answer 4

delays in vitro culture results

defeats some antibiotics

Question 5

What feature makes mycobacterium gram stain poorly?

Answer 5

Mycolic acid cell wall surface

Question 6

How are mycobacteria stained?

Answer 6

Acid fast procedure

Question 7

If an organism is G+, will it be acid fast +/-?

Answer 7

Acid Fast -

Question 8

Is TB acid fast +/-? G+/-?

Answer 8

Acid fast +

G-

Question 9

How is TB transmitted to lungs?

Answer 9

inhalation

Question 10

How is TB transmitted to lymph nodes, kidney, bones, and CNS?

Answer 10

hematogenous spread (through blood)

Question 11

How is TB transmitted to GI?

Answer 11

swallowing infected sputum

Question 12

An immunocompetent host raises a strong _________ and can hold TB infection latent for _______

Answer 12

CMI (cell-mediated immunity) response

Decades

Question 13

In a host with a latent TB infection, what will reactivate the infection?

Answer 13

Immunosenescence/

immunosuppression

Question 14

What percent of cases represent classic pulmonary TB?

Answer 14

75%

Question 15

What are the symptoms of classic pulmonary TB?

Answer 15

cough
weight loss (consumption)
fever
night sweats
hemoptysis (expectorating blood)
chest pain

Question 16

What tests are done to detect TB?

Answer 16

check sputum

chest X ray

Question 17

How does TB use a Trojan horse mechanism to infect?

Answer 17

intracellular infection of naive macrophages through hematogenous spread

Question 18

How does the immune system respond to the Trojan horse attack by TB?

Answer 18

activated macrophages kill it
CD8 cells kill infected macrophages
Establish caseating granulomas - contain infection

Question 19

How do reactivations of TB manifest? Give examples

Answer 19

Extrapulmonary

Question 20

Scrofula in neck, genitourinary, CNS (meningitis), skeletal (long bone or spine), and GI (very rare) are locations for what?

Answer 20

Extrapulmonary reactivation of TB

Question 21

What characterizes pediatric TB? What lethal primary infections must be watched for?

Answer 21

recently acquired –> need to trace source

watch for miliary TB and meningitis

Question 22

Which tests are performed to determine TB exposure? How long do cultures take?

Answer 22

TST and/or IGRA

~2 weeks

Question 23

How long does antibiotic resistance testing take for TB?

Answer 23

3 weeks

Question 24

Wha treatment protocol is started for TB patients?

Answer 24

-Directly Observed Therapy
4-plus-drug course (featuring isoiazid)
isolate patient for first 2 weeks

Question 25

What is the name of the TB vaccine used abroad? Why isn't it used in the US?

Answer 25

``` BCG vaccine (live attenuated M. bovis) not cost-effective here can create weak-moderate false + TST ```

Question 26

What are the most helpful factors for reducing the incidence of TB in a population?

Answer 26

good diet | housing

Question 27

Is latent TB contagious?

Answer 27

No

Question 28

What are atypical mycobacteria?

Answer 28

Environmentally-acquired infections which cause neither TB nor leprosy

Question 29

Atypical mycobacterial infections in immunocompetent adults are usually _______

Answer 29

cutaneous (skin)

Question 30

Atypical mycobacterial infections in children are ususally _________

Answer 30

scrofula

Question 31

Atypical mycobacterial infections in immunocompromised hosts have _______ symptoms which mimic _______

Answer 31

systemic | TB

Question 32

Which two organisms usually cause micobacterial infections in immunocompromised hosts?

Answer 32

M. kanasaii or MAI/C

Question 33

Atypical micobacterial infections may be _________ once established, and require _________

Answer 33

difficult to treat | multiple antibiotics

Question 34

M. leprae is difficult to study for these 3 reasons

Answer 34

no in vitro culture system extremely long incubation period doesn't transmit easily

Question 35

What percent of people are believed to be susceptible to M. leprae?

Answer 35

5-10%

Question 36

Leprosy is also called ______

Answer 36

Hansen's disease

Question 37

Leprosy presents on a range from _______ to ________

Answer 37

Tubuerculoid to Lepromatous

Question 38

What characterizes tuberculoid leprosy?

Answer 38

paucibacillary vigorous CMI (infection + damaged nerves) PPD+

Question 39

What characterizes Lepromatous leprosy?

Answer 39

multibacillary weak CMI extensive cutaneous symptoms PPD-

Question 40

Lepromin PPD tests _____ and position on the ______

Answer 40

anti-leprosy response and position on the tuberculoid-lepromatous spectrum

Question 41

Lepromin PPD not NOT test _______

Answer 41

exposure

Question 42

How is leprosy treated?

Answer 42

2 years of dapsone + rifampin