AFB

Acid-fast bacilli

Bacteria that retain certain dyes, such as carbol fuchsin, even after being washed with acid-alcohol, a trait due to their waxy, mycolic acid-rich cell walls. This property is used in the Ziehl-Neelsen or Kinyoun staining techniques to identify Mycobacterium species.

1. Mycobacterium tuberculosis (M. tuberculosis): The primary cause of tuberculosis (TB), it infects the lungs but can also affect other organs, leading to systemic complications.
2. Mycobacterium leprae (M. leprae): Responsible for leprosy (Hansen’s disease), it primarily affects the skin, peripheral nerves, and mucous membranes.
3. Mycobacterium avium complex (MAC): A group of related bacteria (including M. avium and M. intracellulare) that cause opportunistic infections, particularly in immunocompromised individuals, such as those with HIV/AIDS.

These Mycobacterium species are problematic due to their ability to cause chronic, often debilitating infections and their complex treatment regimens, requiring prolonged multidrug therapy.