Flashcards in 19 Mycobacterial diseases Deck (21)
How are mycobacteria different to all other bacteria? (4)
Waxy cell wall- high lipid content.
Poor gram staining (ghost cells).
Acid fast bacilli (Ziehl Neelsen, Phenol Auramine).
Name three atypical mycobacteria:
Why are they atypical?
Lack of person-person transmission.
What is primary tuberculosis? (4)
Usually in periphery of mid zone lung.
Inhaled bacilli phagocytosed by macrophages. Gohn focus in hilar lymph nodes.
Intracellular multiplication and dissemination.
Describe tubercle formation (the body's response to primary TB):
Cell mediated granuloma formation.
Central area of epitheliod and giant cells (capable of TB killing).
Central area of caseous necrosis, fibrosis and calcification.
Surrounding lymphocytic infiltration.
May remain viable for 20 years.
When does reactivation Tuberculosis occur? (8)
Western: 50yo men.
Silicosis, chronic renal failure, gastrectomy.
Anti TNFα blockade (infliximab).
How does TB reactivate and where does it do it?
Tubercles coalesce and cavitate.
Lung apices (oxygen tension).
Chronic productive cough, haemoptysis, weight loss, fever, night sweats.
What are the symptoms of TB meningitis? (6)
Focal neurological deficit
May lack constitutional quartet.
What is the constitutional quartet associated with TB?
How is TB diagnosed using microbiology? (4)
3 early morning sputum specimens.
Direct microscopy for AFBs.
Lowenstein-Jensen culture (3-4wks).
Whys is PCR used less than culture for TB diagnosis? (3)
Less sensitive than culture.
Not 100% specific.
What is the Xpert MTB/RIF test?
Direct to sputum, 2hr result.
Highly specific and sensitive.
What is the treatment for standard pulmonary TB?
First 2months: isoniazid, rifampicin, pyrazinamide, ethambutol. Next 4 months: isoniazid, rifampicin.
12 months + initial corticosteroids
Which drugs are MDR and XDR resistant to?
MDR: isoniazid + rifampicin.
XDR: fluoroquinolone + isonazid + rifampicin.
Which are the new drugs with shorter treatment times for TB? (3)
What tests are available for TB? (3)
Interferon gamma release assays.
TB specific antigens: ESAT6 and CFP10.
What is the BCG vaccine and who is it given to? (2)
Attenuated M bovis stain.
Neon or exposure risk.
What does Mycobacterium avium cause? (3)
Disseminated disease in HIV +ve.
Cervical lymphadenitis in children.
Macrolide: clarithromycin/ azithromycin.
What does Mycobacterium leprae cause? (w types)
Tuberculoid - macules/plaques, ulnear/common peroneal nerve.
Lepromatous - subcutaneous tissue accumulation, leonine facies.
How is Mycobacterium leprae treated? (3)
What is miliary TB?
How does it occur?
Extra-pulmonary + disseminated.
Erosion of necrotic tubercle into blood vessel.
Very young/old, immunocompromised.