Mycobacterium Flashcards
What bacteria are apart of Mycobacterium?
- Tuberculosis
- Leprae
What kind of stain do you use for mycobacterium species?
Acid fast stain
It takes very long to develop a mycobacterium disease because why?
because the generation time (doubling time) is about 20 hours.
What bacteria are apart of the M. avium complex (MAC complex)
- M. avium subspecies avium
- M. avium subspecies silvaticum
- M. avium subspecies paratuberculosis
M. avium complex (MAC) causes what sort of complications?
Opportunistic infections in AIDS
What bacteria are apart of the M. Tuberculosis complex?
- M. tuberculosis
- M. africanum
- M. bovis
- M. microti
- M. caprae
Which mycobacterium causes buruli ulcer?
M. ulcerans
Which mycobacterium causes swimmers ulcer or fishtank granulomas?
M. Marinum
what is the cell wall of M. tuberculosis made of?
mycolic acid
Characteristic of M. tuberculosis?
- obligate aerobic bacilli
- Acid fast bacteria
- very fastidious (only grows when specific nutrients are present)
- Very slow (~20hr doubling)
- resistant to common antibiotics
What are the 4 obligate Aerobes?
“Nagging Pests Must Breath”
- Nocardia
- Pseudomonas
- Mycobacterium
- Bacillus
What stain do you use for M. tuberculosis?
Ziehl-Neelsen Stain
How do M. tuberculosis appear when stained with Ziehl-Neelsen Stain?
Bright red bacilli (rods)
What sort of colonies of M. tuberculosis are formed on Lowenstein Jensen medium?
Rough, Buff, and Tough colonies
What kind of media do you use for M. tuberculosis?
Lowenstein-Jenson Media (Midlebrook medium)
1 of 4 deaths in M. tuberculosis is related to what?
HIV-related
What is the route of transmission for M. tuberculosis?
Person to person transmission by infectious aerosols
These kind of people are more prone to have M. tuberculosis…?
- Medically underserved
- Poor
- Homeless
- Prison inmates
- Alcoholics
What are the VF of M. tuberculosis?
- LAM
- Cord factor glycoprotein
- Mycolic acid
What is the role of Lipoarabinomannan (LAM)?
- Inhibits macrophage activation
- Prevents phagosome fusion with lysosome
What is the role of Mycolic acid?
- Makes M. tb resistant to complement
- IMPORTANT in granuloma formation
What is the role of Cord factor?
- Interferes with phagosome maturation
- Induces release of TNF-alpha
What is the role of 19kDa Lipoprotein?
- Induces apoptosis in late stage of infection
What is the role of PDIM (pthiocerol dimycocerasate)?
- Interferes with MHC-II loading in vacuole
- May prevent pH from lowering
Pathogenesis of primary infection with M. Tb
- organism engulfed by Alveolar macs
- non resistant macrophages attracted
- macrophages transport bacteria to hilar LN
- CMI stimulated
What is involved in Ghon complex?
Lung lesion + Enlarged LNs
In M. Tb, the CMI leads to formation of what?
Tubercles/Granulomas
Progression of M. Tb leads to what?
cavitation or bursting of contaminated MTB
Large granuloma histological findings?
- Necrotic center
- caseous with fibrin, liquid, calcification
- Breaks open to release bacteria
where to MTBs reside?
in macrophages
Clinical findings of a chronic disease?
- Calcification
- Fibrosis, scarring
- persist for life
- Show up as radio-opaque nodules
Reactivation of dormant M. Tb is usually where?
Apex of the Lung
Tubercles are found in many tissues including?
- Bones: Potts disease
- Kidney: Cement or Putty kidney
- Meningitis
- Liver
- Gut
Miliary TB is also called?
Disseminated TB
Disseminated TB is characterized by what?
- wide spread into the human body via blood stream in the macrophages.
- They resemble millet seeds
What is the diagnosis steps for M. Tb?
- Tuberculin Skin test (positive)
- Chest x-ray and clinical exam (abnormal)
- Sputum culture (positive)
- Active TB treatment
how many consecutive sputum samples do you have to take in order to consider positive MTB?
3 consecutive sputum cultures. (treat with 2% NaOH)
If chest x-rays are normal for MTB and sputum culture is negative for MTB what does this mean?
Latent Tuberculosis
What kind of hypersensitivity type is the Mantoux Tuberculin test?
Type IV, CMI response
Mantoux test in Exposed/HIV+ individual?
5-9mm positive if person is in category 1
Mantoux test in High risk/HIV- individual?
10-14 mm positive if person in category 2
Mantoux test in Low Risk/HIV- individual?
Greater then or equal to 15mm positive if person in category 3
M. Tb x-ray shows what?
Cavity like lesion in upper lobe of lung
what are the sputum culture biochemical tests for M. TB for Niacin, Nitrate reductase and Catalase?
- Niacin is (+)
- Nitrate reductase is (-)
- Catalse is (-)
What are the pros and cons for using Sputum Immunofluorescence for diagnosing M. Tb?
pros: don’t have to wait for culture
- too few bacilli in sample
What stain do you use for M. TB sputum immunofluorescence?
Rhodamine-Auramine Stain
- high sensitivity
- low specificity
What is the Quantiferon TB test?
Patients blood sample is mixed with Tb antigens in vitro.
What does the Quantiferon diagnostic TB test quantitate?
it quantitates INF-Y production by pre-sensitized cells.
What is the treatment for M. TB for 2 months?
- Isoniazid
- Rifampin
- Pyrazinamide
- Ethambutol
What is the treatment for M. TB for 4-6 months?
- Isoniazid
- Rifampin
What do you use as treatment of M. TB if bacteria is Multi-drug resistant (MDR)?
- Pyrazinamide
- Ethambutol
What do you use as treatment of M. TB if bacteria is Extensively drug resistant (XDR)?
Fluoroquinolones (Ciprofloxacin)
what is the Bacillus calmette Guerin (BCG) vaccine prepared from?
Live attenuated M. bovis strain
What are the symptoms of Mycobacterium tuberculosis infection?
- Bad cough lasting 3 weeks or longer
- Cough up blood
- weakness
- weight loss
M. Leprae is similar to M. TB, except for the following?
- Cannot grow in cell free culture
- Prefer lower temps
- Affects human and animals (armadillos)
- Targets nerves of the extremities
M. Leprae’s 2 disease manifestations are due to what?
due to Th1 or Th2 response
what are “leonine facies” of Lepromatous leprosy?
- Loss of eye brows
- Nasal collapse
- Lumpy earlobe
What is the reservoir for Mycobacterium Leprae in USA?
Armadillos
Leprosy is also known as?
Hansen’s Disease
What are Hansen’s disease 2 forms?
- Lepromatous
- Tuberculoid
What is Lepromatous leprosy characterized by?
Low cell mediated immunity with a humoral Th2 response
What is Tuberculoid leprosy characterized by?
High cell mediated mediated immunity with a largely Th1 type immune response
Which Mycobacterium complex has a very strong associated with AIDS patients?
M. avium complex (MAC)
