Which of the following is the most infective form of TB
Infectivity (in decreasing order)
Cavitary lesion, endobronchial/ laryngeal tuberculosis > smear negative > culture negative > extra pulmonary
Extra Edge: Cavernous breathing is heard in a cavity. (LQ)
Extra Edge: Pathogenesis (Ref. Hari-18th ed., Pg- 1342)
2 – 4 weeks after infection two host response develop –
1). Tissue damaging response – Result of delayed type hypersensitivity reaction to bacillary antigen. It destroys non activated macrophages that contain multiplying bacilli.
2). Macrophage – activating response – It results in the activation of macrophages that are capable of killing and digesting tubercle bacilli.