Written by the Fiveable Content Team • Last updated August 2025
Written by the Fiveable Content Team • Last updated August 2025
Definition
Mycobacterium tuberculosis is a pathogenic bacterial species in the Mycobacteriaceae family, responsible for causing tuberculosis (TB). It primarily affects the lungs but can also infect other parts of the body.
M. tuberculosis is an acid-fast bacterium identified using Ziehl-Neelsen staining due to its waxy cell wall.
It grows slowly with a generation time of approximately 15-20 hours, making it challenging to culture in laboratories.
The bacterium is aerobic and thrives in oxygen-rich environments like the lungs.
Transmission occurs through airborne droplets when an infected person coughs or sneezes.
Multidrug-resistant tuberculosis (MDR-TB) arises when M. tuberculosis becomes resistant to first-line antimicrobial drugs such as isoniazid and rifampicin.