ID: Mycobacterial diseases

Question 1

list the three major mycobacteria pathogens and what dz it causes

Answer 1

mycobacterium tuberculosis–TB
mycobacterium leprae– leprosy
mycobacterium avium0intacellulare=TB like dz

Question 2

hansen’s dz

Answer 2

leprosy

Question 3

Leprosy

• resevoir
• where does bacteria grow
• states MC in us?
• two forms
• MC in?
• tx

Answer 3

armadillos
-bacteria likes to grow in cooler temps than the normal body temp—>skin and superficial nerves
US states: cali, hawaii, louisiana, texas

TWO FORMS–MC in immunocomp PT

1. Tuberculoid type–causes hypopigmented macular-plaque like skin lesions, thickened superficial nerves and anesthesia of the skin lesions occur
   * ASYMMETRIC nerve involvement
2. Lepromatous type–nodlar, plaque or papular skin lesions (lepromas)
   - poorly defined borders
   - hypopigmented lesions–face, ears, wrists, elbows, buttocks and knees
   - loss of eyebrows and eyelashes
   - SYMMETRIC nerve involvement (sensation preserved)

tx:
* lepromatous: dapsone, rifampin, clofazimine x2-3 years
* tuberculoid: dapsone + rifampin 6-12MO and then dapsone for 2 years

Question 4

M. avium

• two species
• cause what
• MC in?
• tx (1st line, 2dn line, life threatenig case)
• prophylaxis

Answer 4

MAC–m. avium complex
and
M. intracellulare
***very difficult to distingish from one another in lab work

cause pulmoanry dz that is indistinguishable from TB
*ESP in AIDS with CD4 <200

TX:

• *very drug resistant and usually includes MANY (up to 6) drugs for tx
  1. Clarithromycin + Ethambutol + a Rifamycin (rifampin or rifabutin)
  2. add aminoglycoside to tx if it is a life threatening case
  3. SECOND LINE: ethambutol + rifamycin + Aminoglycoside

Prophylaxis if CD4 <50
*Clarithromycin or Azithromycin

Question 5

best initial test for TB?

-MC finding in this test?

Answer 5

CXR

MC finding= apical involvement with infiltrates and cavitation

Question 6

what is the single most sensitive test for TB

Answer 6

pleural biopsy

Question 7

what is the most specific test for TB?

Answer 7

culture– but takes 4-6 weeks for TB to grow so it is not often available to guide initial tx

Question 8

do not use what to diagnose acute cases of TB

Answer 8

PPD

Question 9

when to we do the sputum and culture tests for TB? and how many samples

Answer 9

early morning

at least three samples

Question 10

high risk populations for TB

Answer 10

1. highest risk of exposure–>healthacre workers
2. highest risk of infection–>immigrants who come from countries with TB, homelessness
3. highest risk of active TB once infected–>immunodeficiency

Question 11

% of people with latent TB who will become symptomatic

Answer 11

5%

95% will NOT become symptomatic

Question 12

stages and CM of TB

Answer 12

1. primary—outcome of initial infection
   * usually self limiting
   * primary rapid progressive TB= active initial infection WITH clinical progression–>YES CONTAGIOUS MC in kids
2. Chronic (latent) TB: most people “control” the initial infection by forming granuloma–>can become caseating,
   + PPD 2-4 weeks after infection
   NOT CONTAGIOUS
3. Secondary or reactivation:
   *reactivation of the latent TB
   *MC due to immune deficiencies–HIV, ETOH, DM, elderly, steroid use, CA
   *MC sign is upper/apex lobe with cavitary lesions on CXR
   YES CONTAGIOUS

Question 13

what does caseating granuloma mean

Answer 13

central necrosis, acidic with low 02, making it a hostileenvironment for the TB

Question 14

when does a PT usually get a + PPD after infeciton with TB

Answer 14

2-4 weeks after initial infection

Question 15

list the 3 +PPD results and who belongs in each category

Answer 15

> 5mm= HIV, recent contact with infected perosn, nodular or fibrotic changes on CXR, organ transplant

> 10mm= recent arrivals (<5yrs) from high prevalence country, IVDU, healthcare workers, comobrid conditions, kids<4,

> 15mm= persons with no known risk factors

Question 16

can PPD differentiate b/w active and latent PPD?

Answer 16

NO!!!!

*history and presentation help yu differentiate

Question 17

who gets the TB blood test

Answer 17

• ppl with the BCG vaccine

- ppl who have difficult time returnig for a second apt to lok for PPD rxn

Question 18

what is the blood test for TB called

Answer 18

interferon-gamma relese assays

Question 19

diagnosis for TB

• gold standard?
• single most accurate test?

Answer 19

CXR
sputum sample
sputum culture– GS
pleural biopsy– most accurate

Question 20

match the CXR finding to the stage of TB dz :

1. middle/lower lobe consolidation
2. apical (upper lobe) fibrocavitary dz
3. millet-seed like nodular lesions
4. residual evidence of helaed primary TB
5. calcifed primary focus and lymph node
6. healed fibrocalcific ghon complex

Answer 20

1. primary tb
2. reactivation
3. miliary
4. granuloma
5. ghon’s complex
6. ranke’s complex

Question 21

sputum sample for TB 
-how many 
-time of day 
-stain 
-

Answer 21

3 samples
–one has to be early AM
Ziehl-Neelsen stain– look for acid-fast bacilli– will appear RED on a blue background
**then this is sent out for culture

Question 22

tb TX

active

Answer 22

6 mo regimen preferred

1. 2 months of RIPE (or streptomycin if contra for ethambutol)
2. then 4 months of rifampin and isoniazid
   * ***once the culture is determined to be isoniazid sensitive—- ethambutol can be discontinued

Question 23

when can ethambutol be discontinued?

Answer 23

once the culture is determined to be isoniazid sensitive

Question 24

MC SE with: 
R
I
P 
E 
S

Answer 24

rifampin: hepatitis, rash

Isoniazid: peripheral neuroapthy (Vit B6 def), hepatitis, rash, seizures

Pyrazinamide: hepatoxoicity, rash, joint aches, photosensitivity, (CONTRA for PT with gout)

Ethambutol: optic neuritis, contra for gout

Streptomycin: ototoxicity, nephrotic

Question 25

when can TB PT come out of resp isolation

Answer 25

2 weeks after starting therapy

Question 26

tx for latent tb

Answer 26

INH and Pyridoxine x 9 mo

HIV= same drugs but for 12 MO