Flashcards in 44. Leprosy & Non-TB mycobacteria Deck (13)
M. leprae epi?
250,000 new cases/year
M. leprae transmission?
- via nasal droplets
- humans = principal reservoir
- type of leprosy (lepromatous > tuberculoid)
- bacterial burden (multibacillar > Paucibacillar)
- close contact
- genetics (NOD2 mutation, HLA)
M. leprae microbiology?
- slow multiplier and obligate intracellular org
- can’t be grown on artificial media
- grows best in cooler areas of body
- infects macrophages and schwann cells
M. leprae pathogenesis?
- pagocytosed by macrophages via complement receptors
- type of cell-mediated response dictates clinical presentation: mycobacterial presentation of different stress proteins could inf immune response or specific HLA-DR alleles
- Th1 = tuberculoid (low infectivity, single area)
- Th2 = lepromatous (high infectivity, disseminated, hypergammaglobulinemia)
M. leprae disease?
Anesthetic skin lesion(s) + thickened peripheral nerve(s)
- few hypopigmented, discrete lesions
- single but progressive nerve involvement
Lepromatous (Th2, immune complex deposition)
- many symmetrical skin lesions, diffuse margins, thickened skin, nodules
- several nerves but slow progression
- loss of eyebrows, saddle nose deformity, ear lobe nodules
M. leprae dx?
- physical exam: skin and nerves
- slit-skin smear (AFB smear)
- biopsy: gold standard
M. leprae tx?
- paucibacillary disease (PB) blister pack
- multibacillary disease (MB) blister pack
- rifampin single dose may prevent disease in close contacts
- BCG 26% efficacy
- Rapid growers: visible colonies in 1 week
- Slow growers: 2-4 weeks
- photochromagen (yellow-orange colonies when exposed to light)
- scotochromagen (yellow-orange colonies in dark or light)
- normochromagens (no pigment)
MAC pulm disease RF, dx, tx?
- RF for MAC pulm disease? COPD, CF, lung disease, immunocompromised – solitary nodule, cavitary disease, nodular bronchiectasis, hypersensitivity pneumonitis
- MAC Pulm: sxs & radiographic & exlusion of other causes; 2 positive sputum cx or single BAL positive for MAC
MAC Pulm: nodulat/bronchiectatic: rifampin, ethambutol, azithromycin/ clarithromycin 3x q week
Fibrocavitary or severe ^^: ^^ qd
MAC disseminated disesae, dx, tx?
- Disseminated MAC: fevers, wt loss, night sweats, abd pain, diarrhea
- elevated LDH
- AFB blood cx,
Bone marrow aspirate
Disseminated: macrolide + etham + rifamycin
M. ulcerans Buruli ulcer disease, dx, tx?
Buruli ulcer produces potent cytotoxin (mycolactone)
- Buruli ulcer: painless papule to ulcer
- rifampin + streptomycin
- or + clarithromycin
M. marinum disease, dx, tx?
- marinum painless/painful papules or nodules w/indolent course
- rifamp + clarithro +