44. Leprosy & Non-TB mycobacteria

Question 1

M. leprae epi?

Answer 1

250,000 new cases/year

Armadillos

Question 2

M. leprae transmission?

Answer 2

• via nasal droplets
• humans = principal reservoir
  RFs:
• type of leprosy (lepromatous > tuberculoid)
• bacterial burden (multibacillar > Paucibacillar)
• close contact
• age
• immunosuppression
• genetics (NOD2 mutation, HLA)

Question 3

M. leprae microbiology?

Answer 3

• 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

Question 4

M. leprae pathogenesis?

Answer 4

• 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)

Question 5

M. leprae disease?

Answer 5

Hansen’s disease
Anesthetic skin lesion(s) + thickened peripheral nerve(s)
Tuberculoid: (Th1)
- 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

Question 6

M. leprae dx?

Answer 6

• physical exam: skin and nerves
• slit-skin smear (AFB smear)
• biopsy: gold standard

Question 7

M. leprae tx?

Answer 7

Multi-drug:

• paucibacillary disease (PB) blister pack
• multibacillary disease (MB) blister pack
• dapsone
• rifampicin
• clofazimine

Prevention:

• rifampin single dose may prevent disease in close contacts
• BCG 26% efficacy

Question 8

NTBMtb microbiology?

Answer 8

• 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)

Question 9

MAC pulm disease RF, dx, tx?

Answer 9

• 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

Question 10

MAC disseminated disesae, dx, tx?

Answer 10

• Disseminated MAC: fevers, wt loss, night sweats, abd pain, diarrhea

Disseminated MAC
- elevated LDH
cytopenias
- AFB blood cx, 
Bone marrow aspirate

Disseminated: macrolide + etham + rifamycin

Question 11

M. ulcerans Buruli ulcer disease, dx, tx?

Answer 11

Buruli ulcer produces potent cytotoxin (mycolactone)

• Buruli ulcer: painless papule to ulcer

Buruli ulcer:

• rifampin + streptomycin
• or + clarithromycin

Question 12

M. marinum disease, dx, tx?

Answer 12

• marinum painless/painful papules or nodules w/indolent course

Marinum:
- rifamp + clarithro +
Ethambutol (severe)

Question 13

rapid grower NTBMtb disease, dx, tx?

Answer 13

• rapid growers skin if indolent skin lesion not
  responsive to standard Abx
• Cipro or doxy or Bactrim or clarithro
  (cutaneous disease)