Aim and Background. The aim of this study was to investigate the frequency, location and type of rpoB mutations in Mycobacterium tuberculosis isolated from patients in Tehran City.

Materials and Methods. 65 sputums were collected from suspected tuberculosis patients, 35 Rif-r isolates were identified as Mycobacterium tuberculosis. PCR Amplification and DNA sequencing methods were performed. 411 bp fragments of rpoB gene were sequenced and mutations in 81 bp regions were analyzed.

Results. 38 mutations were identified in 14 RIF-r MBT (70%). Missense mutations produced 38 types of amino acid substitutions. In 6 RIF-r MBT isolates (30%) no mutations were found in the core region of the rpoB gene. Most frequent mutations detected from Tehranian strains were in codons 531 and 515. Two alleles in codon 531 and one allele in all codons 526, 515, 510, 566, 490 and 476 were found. In the 6 isolates were identified 2 mutation in different codons and 8 strains harboured single mutations in codons .

Conclusion. In this study, has been investigated the significance of mutations in the rpoB gene, its correlation with genotype and phenotype agents and high level of resistance to rifampicin in 14 isolates of M. tuberculosis collected from patients with active pulmonary tuberculosis from different geographic regions of Tehran.

Aim and Background. spoilgotyping is a method based on 36bp DR(Direct Repeat) chromosomal loci polymorphism which is connected to one or two 35- 41 spacersequences. There have been 94 differet intra DR spacer sequences identified and only 43 of them are used as usual. Mycobacterium tuberculosis complex strains can be identified in order to lacking or having these sequences.

Materials and methods. spoilgotyping test was done on 149 TB smear positive patients.Primary separation of mycobacterium strains was done through petrof 4% method and by Lowenstein Jensen(LJ) media. Biochemical tests such as Niacin test / Catalase activity / Nitrate reduction were done due to strains identifying. Drug sensitivity to INH(2Mg/ml) / RIF(40Mg/ml) / STM(10Mg/ml) and ETBI(2Mg/ml) was accomplished proportional and strains were distributed to three groups: sensitive, MDR, non MDR. DNA was extracted by CTAB method on positive clonies. Sequences were amplified by PCR and after denaturating amplified sequences, hybridation with Streptavidine peroxidase enzyme through line reverse blot method was accomplished. Luminoscense was added and the membrane was put onto the X-ray film. Then we did radiology step.

Results: Serotypes were divided into 9 groups (Beijine/CAS23/Haarlem/U/T2/T1/EAI3/EAI2/CAS2). The majority group was Haarlem (27%) and minority one was T2 (0.4%). There were also identified 2 strains belonging to Mycobacterium bovis.

Conclusion: Used method in this study is easy/precipitate and has high sensitivity. In every time using this method there could be 43 samples distinguished.