Mycobacterium leprae
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Bacteria - Gram Indeterminate
- Mycobacterium tuberculosis: Overview
- Mycobacterium tuberculosis: Disease (TB)
- Mycobacterium avium
- Mycobacterium scrofulaceum
- Mycobacterium leprae
- Gardnerella vaginalis (Bacterial Vaginosis)
- Mycoplasma pneumoniae
Mycobacterium leprae
- Characteristics
- Acid fast rod
- All mycobacterium are acid fast rods
- Reservoir in the US is the armadillo
- Otherwise far more common in developing world
- Acid fast rod
- Causes Leprosy - 2 forms:
- Typically affects skin and superficial nerves
- Grows best in temperatures below core body temperature
- Typically found in extremities (skin, superficial nerves, eyes, etc.)
- Tuberculoid (less severe)
- Strong Th1 cell response and activation of macrophages kill bacteria, causing low bacterial load
- Well-demarcated hypopigmented, hairless skin plaques with decreased sensation
- Caused by local inflammation secondary to immune system activation
- Lepromin skin test: raised nodule (like PPD)
- M. leprae antigen injected intradermally
- Demonstrates cellular response
- Lepromatous (more severe, disseminated)
- Largely Th2 cell response fails to kill bacteria, causing high bacterial load
- Diffuse, poorly-demarcated skin lesions
- Leonine facies (lion-like)
- Caused by coalescence (merger) of skin lesions
- Loss of nose and digits of extremities can occur
- Lepromin skin test: non-reactive
- M. leprae antigen injected intradermally
- Demonstrates lack of cellular response
- Typically affects skin and superficial nerves
- Diagnosed via skin biopsy or tissue PCR
- Treatment
- Dapsone and Rifampin for tuberculoid form
- Dapsone, rifampin, plus Clofazimine for lepromatous form