L44 Flashcards
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
What are tell tale signs/symptoms of TB meningitis?
Sub-acute neuro signs: headache, fever, AMS
High WBC
Low glucose
What is miliary TB?
TB bacteremia –> dissemination into various organs
- Often liver
- *MILLET SEEDS on CXR**
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
What is a major drawback of PPD/IGRA tests?
CANNOT distinguish between active and latent TB!!!!
Describe the AFB sputum culture to diagnose pulmonary TB.
Rapid
Cheap
Determine drug susceptibility
CanNOT distinguish M.TB from non-tuberculine mycobacterium
Describe NAAT to diagnose pulmonary TB.
Rapid
$$
Higher sen & spec
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
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 & fast in liquid media - Susceptibility testing too - **Developing world**
In cultures, what shape characteristic tells you M.TB from other mycobacteria?
Cording!
Which diagnostic test would you use to determine rifampin resistance for M.TB fast?
Molecular assays - GeneXpert
= PCR
Looking at rpoB gene
What conditions must be met to take a possible TB patient out of airborne isolation?
3 negative AFB sputum cultures
Alternative diagnosis
If you think a patient has TB, what must you also test them for?
HIV
Is pulm or extra-pulm TB more common in HIV patients?
W/ low CD4 counts - extra-pulm
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
What are 2nd line TB drugs?
Fluoroquinolones (often substituted for ethambutol w/ TB meningitis)
Injectables - amkicain
Give if resistant to 1st line
Describe the time course & combinations that TB drugs are given in.
2 mos = RIPE
4 mos –> on = RI
What do you give with isoniazid to prevent neuropathy?
Vit B6
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
What animals carry M.leprae?
Amradillos!
And humans…
Can M. leprae be cultured?
No
Doesn’t take up stain - must use acid fast stain
Where does M.leprae grow on the body?
Cooler areas - skin & extensor surfaces
What cells does M.leprae infect?
Obligate INTRACELL
Prefers macrophages & Schwann cells
How is M.leprae transmitted?
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
