IS 6110 is the most popular target for PCR to detect Mycobacterium tuberculosis(MTB) in various clinical specimens. But the absence of IS 6110 has been reported in a few strains of MTB. To overcome these drawbacks comparative study in detecting
MTB
has
been made with primer pairs based on DNA sequences of IS 6110, IS 1081, pab gene and mpt40.
IS 6110, IS 1081,2 and pab gene amplified DNA of MTB and M. bovis, while mpt40 did only MTB DNA among various microbial DNA tested. Detection limits of IS 6110, IS 1081, pab gene, and mpt40 primer pairs were 5fg, 50fg, 500fg, 5pg of purified MTB
DNA
respectively.
The similar sensitivity was observed in detecting MTB in clinical samples. Of 107 smear negative sputum, positive rates of IS 6110 and IS 1081 primer primer pairs were 25.2%(27cases) and 21.5%(23cases) respectively. Four(4.9%) out of 82 negative
cases
with IS 6110 showed positive amplification with IS 1081 primers, suggesting that MTB of these cases may be devoid of IS 6110 or have less copy number than that of Is 1081. Therefore the combination of two different primer pairs of IS 6110 and IS
1081.
may be useful to prevent false negative due to absense or limited number of target DNA copies in chromosomal DNA of MTB. In additon, primer pair derived from mpt40 is suggestive to differentiate M. tuberculosis from M. bovis.
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