Study of respiratory symptoms among sputum positive

Tuberculous Mycobacteria
The most common agent ofpulmonary tuberculosis is the acid fast
bacillus M.TB. It's a species of the genus mycobacterium, family
mycobacteriacae, order actinomycetales (Jeraff, 1986). There are five
closely related mycobacteria grouped in the M. tuberculosis complex: M.
tuberculosis, M. bovis, M. africanum, M. microti and M. canetti
(Vansoolingen et aI., 1997 and 1998).
Morphology and growth requirements:
Mycobacterial tuberculosis (M.TB) is a slender, straight or slightly
curved rod, 0.5 I-l in length and 0.34 ).l in breadth. The bacilli are non
motile, gram positive, aerobic, and do not form spores or capsules (ATS,
1987). The growth requirements of mycobacteria on artificial media
include potassium, magnesium, phosphorus, and sulfur. Ammonium salts
or egg ingredients provide a nitrogen source, and glucose or glycerol
supply a carbon source. The optional pH range for growth is 6.5 to 7.0.
Although mycobacteria are strict aerobes, a CO2 concentration between 5 %
and 10 % is necessary for their primary recovery on solid media. The
incubation conditions should include high humidity and atemperature of
35 to 37°C (Zheng and Roberts, 1999).
Cell wall structure:
The cell envelope essentially distinguishes species of the
. I mycobacterium genus from other prokarytes. Mycobacteria in general give
.W
a weakly positive response to the gram stain,are phylogenetically more
closely related to gram positive bacteria (Draper, 1982), and lackthe
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