|EFFECT OF CARBON DIOXIDE ON THE PRIMARY ISOLATION
|MM Chauhan, TR Sreenivas & K Chaudhuri: Indian
J TB 1991, 38, 81-85.
The stimulatory effect of carbon dioxide (CO2)
on the growth of tubercle bacilli was reported by a few authors.
A study was done to see the effect of CO2 on primary isolation of
mycobacteria on Lowenstein Jensen medium in terms of (1) positivity
rate (2) improvement in the rate of growth in cultures and (3) contamination
One thousand and five clinical specimens were inoculated,
after processing by modified Petroff's method, onto LJ medium and
incubated with or without addition of 10% of carbon dioxide. Of
the total positive cultures, 30.8% grew only under 10% carbon dioxide
and in 58.3% growth was first seen in that atmosphere. The results
of this study show that (1) 10% carbon dioxide increases the
yield of mycobacteria in primary culture (2) it stimulates the
temporal growth rate resulting in reduction of lag period
by one week (3) the increase in yield is largely from smear negative
specimens and (4) there is no significant increase in the contamination
rate to offset the stimulating effect on mycobacterial growth.
|KEY WORDS: M.TUBERCULOSIS, CARBONDIOXIDE, GROWTH