DETECTION BY PCR OF MYCOBACTERIUM-TUBERCU LOSIS LACKING IS-6110

We have evaluated the frequency of M. tuberculosis strains which lack IS 6110 among 102 sputa isolated from Moroccan patients. A pair of pri mers was designed to amplify a 201bp DNA fragment of IS 6110. The ampl ified DNA was detected by ethidium bromide stained agarose gel electro phoresis and confirmed by southern blot hybridization with a P-32-labe lled probe (PMTO2), To detect the presence of amplification inhibitors , an internal control DNA was added in each negative PCR result. Among 102 samples, 6 sputa were negative by PCR-IS 6110 but culture positiv e. The test of detection of M. tuberculosis for 2/6 sputa by PCR Ampli cor amplifying 584 pb of rRNA 16s sequence was positive, RFLP analysis of these 2 strains revealed no bands hybridizing IS 6110 but PCR-Mt 3 08 was positive. These results confirmed that these M. tuberculosis st rains are lacking IS 6110.