TB bacteremia --> dissemination into various organs - Often liver MILLET SEEDS on CXR

L44 Flashcards by Logan Kolakowski

What are 3 diseases that could result if TB from the lung moves extra-pulm via bacteremia?

Meningitis
Tuberculoma = cavitary lesions
Pott’s disease of the spine

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What are tell tale signs/symptoms of TB meningitis?

Sub-acute neuro signs: headache, fever, AMS
High WBC
Low glucose

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What is miliary TB?

TB bacteremia –> dissemination into various organs

Often liver
*MILLET SEEDS on CXR**

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What is the difference between pulmonary vs extra-pulm TB cultures?

Take cultures from the tissues you’re concerned about

Pulm = chest
Extra = could be anywhere

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What is a major drawback of PPD/IGRA tests?

CANNOT distinguish between active and latent TB!!!!

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Describe the AFB sputum culture to diagnose pulmonary TB.

Rapid
Cheap
Determine drug susceptibility
CanNOT distinguish M.TB from non-tuberculine mycobacterium

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Describe NAAT to diagnose pulmonary TB.

Rapid
$$
Higher sen & spec

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How do mycobacterium stain?

Acid fast!
Red b/c of carbol fuschin
Other body cells stain blue b/c methylene blue is the counter stain

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Which culture techniques do you use for M.TB? (the 1 solid mediums vs 2 liquid mediums)

1. L-Jensen agar (slow)
OR
2. MGIT = liquid media
- Detects release CO2 by growing M.TB 
- FASTER!
3. Microscopic Observational Drug Susceptibility Assay
- Cheap &amp; fast in liquid media
- Susceptibility testing too
- **Developing world**

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In cultures, what shape characteristic tells you M.TB from other mycobacteria?

Cording!

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Which diagnostic test would you use to determine rifampin resistance for M.TB fast?

Molecular assays - GeneXpert
= PCR
Looking at rpoB gene

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What conditions must be met to take a possible TB patient out of airborne isolation?

3 negative AFB sputum cultures

Alternative diagnosis

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If you think a patient has TB, what must you also test them for?

HIV

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Is pulm or extra-pulm TB more common in HIV patients?

W/ low CD4 counts - extra-pulm

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What are the 1st line TB drugs? Include mechanism of each.

RIPE
Rifampin - X protein synthesis 
Isoniazid - X mycolic acid synth
Pyrazinamide - impact plasma mem, disrupts E metabolism
Ethambutol - X arabnoglyctan synthesis

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What are 2nd line TB drugs?

Fluoroquinolones (often substituted for ethambutol w/ TB meningitis)
Injectables - amkicain
Give if resistant to 1st line

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Describe the time course & combinations that TB drugs are given in.

2 mos = RIPE

4 mos –> on = RI

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What do you give with isoniazid to prevent neuropathy?

Vit B6

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What are the side effects of the RIPE drugs?

Rifampin - hepatitis, organ body fluids
Isoniazid - hepatitis, peripheral neuropathy (neurons & hepatocytes)
Pyrazinamide - hepatitis, GI upset
Ethambutol - optic neuritis, impaired color vision

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What animals carry M.leprae?

Amradillos!

And humans…

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Can M. leprae be cultured?

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Doesn’t take up stain - must use acid fast stain

Where does M.leprae grow on the body?

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Cooler areas - skin & extensor surfaces

What cells does M.leprae infect?

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Obligate INTRACELL

Prefers macrophages & Schwann cells

How is M.leprae transmitted?

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Nasal droplets

Which form of leprosy is more infectious: tuberculoid or lepromatous?

Lepromatous > tuberculoid | B/c multibacillary bacterial burden (aka many M.leprae) > paucibacillary

Why do you describe leprosy as a spectrum?

Tubercolid and lepromatous are the extremes - can present with some spectrum in between Borderline symptoms/skin lesions

Which type of leprosy is a Th2 response? What are the main cytokines?

Lepromatous IL 4, 5, 10 mediated Therefore no T cell response

Which type of leprosy is a Th1 response? What are the main cytokines?

Tuberculoid IL2, IFNg, TNF beta mediated Therefore T cell response specific to M.leprae antigens

Which form of leprosy is contained in granulomas with only localized inflammation and peripheral nerve damage?

Tuberculoid (Th1) | Single but progressive nerve involvement

Which form of leprosy results in a disseminated infection including diffuse bone, cartilage, and nerve damage?

Lepromatous (Th2) | Several nerves affected but slow progression

Which form of leprosy shows organisms growing in macrophages?

Lepromatous (Th2)

What are the common clinical symptoms for both types of leprosy?

Common = skin lesions + thickened peripheral nerves - Loss of eyebrows - Saddle nose deformity - Ear lobe nodules

Name the specific symptoms for tuberculoid vs lepromatous.

Tuberculoid = few, discrete lesions - 1 nerve, FAST Lepromatous = many symmetrical lesions, thickened skin, nodules - Many nerves, slow

How do diagnose leprosy?

Biopsy = gold standard | - Granulomas w/ mycobacteria

How do you treat leprosy?

Multidrug to prevent resistance Paucibacilliary (tuberculoid, Th1) - 6 mo rifampin/dapsone Multibacillary (lepromatous, Th2) - 12 mo rifampin/clofazamine/dapsone

How can you prevent disease in close contacts?

Single dose rifampin

How is non-TB mycobacterium spread?

``` Found everywhere in the environment Inhalation Ingestion Inoculation NOT person-person ```

What are the 2 categories of non-TB mycobacterium?

Rapid growers | Slow growers

What are 3 types of NTM slow growers?

Nonchromagen Photochromagen - yellow colonies in light Scotochromagen - yellow/orange colonies in dark or light

What temps do NTM prefer?

Colder (few strains)

Which clinical syndroms do NTM cause?

Pulmonary disease Skin/ST infections Lymphadenitis

What are the clinical finding of NTM pulmonary disease? Which strain of bacteria is the most likely culprit?

Mycobacterium avium complex Non-transmissible form of disease Chest CT: disseminated nodules

If you get 1 positive sputum culture for NTM - myco avium complex, what's your next step?

Confirm with serial sputum cultures | Need at least 2 + cultures for MAC

What are the big 4 drugs for NTM MAC pulmonary disease?

Rifampin Ethambutol Azithromycin Clarithromycin - need to susceptibility test this

What type of ulcer is caused by NTM?

``` Buruli ulcer - mycobacterium ulcercans Transmitted via skin trauma B/c cytotoxin Treat: - Rifampin + streptomycin or claruthromycin ```

Which strain of NTM causes "fish tank granuloma"? Treat severe vs mild?

``` M.marinum Treat SEVERE disease: - Rifampin - Clarithromycin + ethambutol Treat disease confined to skin: - Cipro, doxy, bactrim, or clathithro ```

Which skin lesions should you suspect for NTM?

Chronic, indolent skin lesions | Unresponsive to standard antimicrobials

Which NTM bug is going to cause disseminated disease? Which patient populations are at risk?

``` Myco avium complex Immunosuppressed pts (HIV) ```

Symptoms and organs involved in disseminated MAC disease.

``` Symptoms: - Fevers, night sweats - Weight loss - Abd pain, diarrhea Organs: - Biliary - Hepato-spleno-megaly - Bone marrow - Colitis ```

How do you treat disseminated MAC?

Macrolide + ethambutol + rifamycin

L44 Flashcards

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