ID: Mycobacterial diseases Flashcards
list the three major mycobacteria pathogens and what dz it causes
mycobacterium tuberculosis–TB
mycobacterium leprae– leprosy
mycobacterium avium0intacellulare=TB like dz
hansen’s dz
leprosy
Leprosy
- resevoir
- where does bacteria grow
- states MC in us?
- two forms
- MC in?
- tx
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
- Tuberculoid type–causes hypopigmented macular-plaque like skin lesions, thickened superficial nerves and anesthesia of the skin lesions occur
* ASYMMETRIC nerve involvement - 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
M. avium
- two species
- cause what
- MC in?
- tx (1st line, 2dn line, life threatenig case)
- prophylaxis
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
best initial test for TB?
-MC finding in this test?
CXR
MC finding= apical involvement with infiltrates and cavitation
what is the single most sensitive test for TB
pleural biopsy
what is the most specific test for TB?
culture– but takes 4-6 weeks for TB to grow so it is not often available to guide initial tx
do not use what to diagnose acute cases of TB
PPD
when to we do the sputum and culture tests for TB? and how many samples
early morning
at least three samples
high risk populations for TB
- highest risk of exposure–>healthacre workers
- highest risk of infection–>immigrants who come from countries with TB, homelessness
- highest risk of active TB once infected–>immunodeficiency
% of people with latent TB who will become symptomatic
5%
95% will NOT become symptomatic
stages and CM of TB
- primary—outcome of initial infection
* usually self limiting
* primary rapid progressive TB= active initial infection WITH clinical progression–>YES CONTAGIOUS MC in kids - Chronic (latent) TB: most people “control” the initial infection by forming granuloma–>can become caseating,
+ PPD 2-4 weeks after infection
NOT CONTAGIOUS - 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
what does caseating granuloma mean
central necrosis, acidic with low 02, making it a hostileenvironment for the TB
when does a PT usually get a + PPD after infeciton with TB
2-4 weeks after initial infection
list the 3 +PPD results and who belongs in each category
> 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
can PPD differentiate b/w active and latent PPD?
NO!!!!
*history and presentation help yu differentiate
who gets the TB blood test
- ppl with the BCG vaccine
- ppl who have difficult time returnig for a second apt to lok for PPD rxn
what is the blood test for TB called
interferon-gamma relese assays
diagnosis for TB
- gold standard?
- single most accurate test?
CXR
sputum sample
sputum culture– GS
pleural biopsy– most accurate
match the CXR finding to the stage of TB dz :
- middle/lower lobe consolidation
- apical (upper lobe) fibrocavitary dz
- millet-seed like nodular lesions
- residual evidence of helaed primary TB
- calcifed primary focus and lymph node
- healed fibrocalcific ghon complex
- primary tb
- reactivation
- miliary
- granuloma
- ghon’s complex
- ranke’s complex
sputum sample for TB -how many -time of day -stain -
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
tb TX
active
6 mo regimen preferred
- 2 months of RIPE (or streptomycin if contra for ethambutol)
- then 4 months of rifampin and isoniazid
* ***once the culture is determined to be isoniazid sensitive—- ethambutol can be discontinued
when can ethambutol be discontinued?
once the culture is determined to be isoniazid sensitive
MC SE with: R I P E S
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
when can TB PT come out of resp isolation
2 weeks after starting therapy
tx for latent tb
INH and Pyridoxine x 9 mo
HIV= same drugs but for 12 MO
