Causative organism

Tuberculosis is caused by mycobaterial infection, with classical tuberculosis associated with Mycobacterium tuberculosis. Other forms of mycobacteria exist and cause a range of related infections in a variety of clinical circumstances (Table 3.43.1). Mycobacteria are slender bacilli that are characteristically stained with the Ziehl–Neelsen stain based on their ability to retain a dye after acid and alcohol washes (acid- and alcohol-fast bacilli; AAFB). The bacteria cannot be cultured using conventional media and instead require special media such as the Lowenstein–Jensen medium, together with a prolonged incubation time of up to 6 weeks.

Table 3.43.1 MYCOBACTERIAL INFECTIONS

Pathological features