Mycobacteria Flashcards
Mycobacterium leprae - area of infection
it likes cool temperatures (infect skin and superficial nerves - glove and stocking loss of sensation
Leprosy (Hansen disease) - how many forms and which
- Lepromatous
2. Tuberciloid
Leprosy (Hansen disease) - lepromatous form - clinical manifestation
presents diffusely over the skin, with leonine (lion-like) facies, and is communicable
Leprosy (Hansen disease) - Tuberciloid form - clinical manifestation
limited to few hypoesthetic. hairless skin plaques
primary tuberculosis - lesion
Ghon complex: Hilar nodes + Ghon focus (calcified TB granuloma forming a nodule) usually in lower to middle lung
secondary tuberculosis after reactivation - lesion
fibrocaseous cavitary lesion (usually upper lobes)
TB - PDD negative if
- no infection
- anergic (steroids, malnutrition, immunocompromised)
- sarcoidosis
tests to diagnose TB
- PPD
2. Interferon-γ release assays (IGRA)
Mycobacteria - bugs?
- Mycobacterium tuberculosis
- Mycobacterium avium-intracellulare
- Mycobacterium scrofulaceum
- Mycobacterium marinum
- Mycobacterium leprae
Mycobacteria - bugs and diseases
- Mycobacterium tuberculosis –> TB
- Mycobacterium avium-intracellulare –> disseminated non-TB disease in AIDS
- Mycobacterium scrofulaceum –> cervical lymphadenitis in children
- Mycobacterium marinum –> hand infection in aquarium handlers
- Mycobacterium leprae –> Leprosy (Hansen disease)
M. tuberculosis - prophylaxis and treatment
prophylaxis: isoniziad
treatment: 1. rifampin 2. Isoniazid 3. Pyrazinamide 4. Ethambutol (RIPE)
M. intracellulare-avium - prophylaxis and treatment
prophylaxis: azithromycin, rifabutin
treatment: Azithromycin or clarithromycin + ethambutol
Can add rifabutin or ciprofroloxacin
M leprae - prophylaxis and treatment
prophylaxis: N/A
treatment: Long-term treatment with dapsone and rifampin for tubrrculoid form. Add clofazimine for Lepromatous form
Antimycobacterial drugs - groups and drugs
- Mycolic acid synthesis –> isoniazid
- Arabinoglycan synthesis (Arabinosyl tranferase) –> ethambutol
- mRNA synthesis (DNA-dependent RNA polymerase) –> Rifamycins (rifabutin, rifampin)
- Intracellular (unclear mechanism) –> pyrazinamide
- streptomycin
Rifamycins - drugs and clinical use
Rifampin, rifabutin
- Mycobacterium tuberculosis treatment
- Leprosy: delay resistance to dapsone
- Meningicoccal prophylaxis
- Chemoprophylaxis in contacts of children with H. influenzae type B
- Can add in M. Avium-intracellulare (rifabutin)
- M. Avium-intracellulare prophylaxis
Rifamycins - toxicity
- Minor hepatotoxicity
- Drug interactions (increases cytochrome P-450) - esp rifampin
- orange body fluids (nonhazardous side effect)
Isonizid (INH) - clinical use
- Mycobaterium tuberculosis prophylaxis
2. Mycobaterium tuberculosis treatment
Isonizid (INH) - toxicity
- hepatotoxicity
- P-450 inhibition
- drug induced SLE
- vitamin 6 - pyridoxine (B6) deficiency (–> peripheral neuropathy, siderblastic anemia)
Pyrazinamide - clinical use / toxicity
treatment of Mycobacterium Tuberculosis
- hyperuricemia
- hepatotoxicity
Ethambutol - clinical use / toxicity
- treatment of Mycobacterium Tuberculosis
- treatment of Mycobacterium acium-intracellulare
Optic neuropathy (red green color blindness)
Streptomycin - clinical use / adverse effects
M. tuberculosis
- Tinnitus
- Vertigo
- ataxia
- nephrotoxicity
positive skin test for TB –> next
Chest xray –> if (-) –> isonizid and B6 for 9 months
mild hepatotoxicity after 1 month of TB treatment with isoniazid - next step
nothing (it is self limited)
but if enzymes more than 100 –> replace it
neuropathy due to B6 def
numbness and tingling in a “stocking-glove” distribution
isoniazid - it is easier to develop B6 deficiency if
malnourishment, pregnancy, DM
miliary TB - chest X-ray
reticulonodular pattern
TB - PPD - when is (+) at 5 or more mm
- HIV (+), recent contacts of known TB case
- Nodular of fibrotic changes on chest x-ray (previous healed TB)
- organ transplant or other immune
TB - PPD - when is (+) at 10 or more mm
- recent immigrants from TB areas (lessthan 5 years)
- IV users
- Residents + employees of high risk (prosin, hospital etc)
- Mycobact lab personel
- Higher risk for TB reactivation (DM, leukemia, ESRD, chronic malabsorption
- children under than 4, or those exposed to adults in high risk catefories
leprosy - diagnosis and treatment
diagnosis: full thickness biopsy of skin lesion
treatment: dapsone + rifampin, add clofazimine if sever
