Transmission

Pathogenesis

ABOUT THE BACTERIA:

Bacillus Mycobacterium tuberculosis (MTB) is a slow growing aerobic bacterium that divides every 16 to 20 hours, this when compared to other bacteria may be slow but not the slowest (as like among the fastest the strain of E.coli which can divide roughly within 20 minutes).Mycobacterium leprae divides every 20 days .

MTB is not classified as either Gram positive or Gram negative as it does not have the chemical characteristics of either. When Gram stained was performed it stained very weakly (which conclude Gram positive or not at all/ghost cells). The MTB can be identified microscopically by its staining characteristics such as if it retains certain strains after being treated with acidic solution and thus classified as an ‘ acid – fast bacillus’ or AFB. In Ziehl – Neelsen stain ,AFB are stained bright red which stands out clearly against blue background .These can also be visualized by fluroscent microscopy and by an auramine – rhodamine stain.

The M.Tuberculosis complex includes 3other mycobacterium which can cause tuberculosis.M.bovis, M.africanum and M.microti .Of these two are are very rare and M.microti does not cause human disease.

Nontuberculosis mycobacteria (NTM) are the other mycobacteria (eg.M.leprae which causes leprosy) which can cause pulmonary disease resembling TB, lymphadenitis, skin disease or diseminated disease egs.Mycobacteria avium, M.kansasii etc.