Bacterium
Mycobacterium leprae
Acid-fast leprosy bacillus (cannot be cultured)
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High-yield clue
Cannot be grown on artificial media, prefers cooler skin and peripheral nerves, and is studied in armadillos; disease spans tuberculoid (paucibacillary) to lepromatous (multibacillary).
Overview
An acid-fast, obligate intracellular bacillus that causes Hansen disease (leprosy). It is the classic teaching organism that cannot be grown on artificial laboratory media.
Classification
- Acid-fast bacillus
- Obligate intracellular
- Aerobic
- Slow-growing
- Non-culturable in vitro
Lab & identification clues
- Acid-fast staining
- Cannot culture on artificial media
- Armadillo / mouse footpad research models
- Prefers cooler body temperatures
Associations
- Hansen disease (leprosy)
- Tuberculoid (paucibacillary) vs lepromatous (multibacillary) spectrum
- Peripheral nerve involvement with loss of sensation
Commonly confused with
- Mycobacterium tuberculosis
- Nontuberculous mycobacteria
Frequently asked questions
What is Mycobacterium leprae?
An acid-fast, obligate intracellular bacillus that causes Hansen disease (leprosy). It is the classic teaching organism that cannot be grown on artificial laboratory media.
What are the lab clues for Mycobacterium leprae?
Lab clues for Mycobacterium leprae include Acid-fast staining, Cannot culture on artificial media, Armadillo / mouse footpad research models, and Prefers cooler body temperatures.
What is Mycobacterium leprae commonly confused with?
Mycobacterium leprae is commonly confused with Mycobacterium tuberculosis and Nontuberculous mycobacteria.
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.