ABSTRACT
st and ardized genotyping systems in molecular epidemiology of tuberculosis in the world. This sudy was done to determine the Mycobacterium tuberculosis genotyping by MIRU-VNTR method. Methods: This descriptive study was done on sputum, gastric lavage clinical specimens of 53 tuberculosis suspected patients. Fifty-three isolates were identified by 16S rRNAandRv-typing followed by RD typing. They were then subjected to a 12-locus [ETRA, ETRB, ETRC, ETRD, ETRE and ETRF, MIRU-10, MIRU-26, MIRU-39, MIRU-30 plus QUB-11b] MIRU-VNTR typing system. Results: In MIRU-VNTR typing, forty-four types were identified with 13 isolates classified in 4 clustered and the remaining 40 isolates representing 40 orphan patterns. In comparative analysis of MIRU-VNTR loci, MIRU-26 with 7 alleles displayed the highest diversity level [Simpson's diversity index = 0.767. Out of the 53 isolates, only one was identified as Mycobacterium bovis. All the remaining isolates were characterized as Mycobacterium tuberculosis. None of the samples was affected to Mycobacterium complex strain. No evidence of either double or co-infection of the patients with more than one species/strain was detected. Conclusion: While the genomic diversity observed by MIRU-VNTR typing sounds extensive, the population genomic structure on the whole however, seems to be homogenous. Recent transmission between studied patients does not appear to be a frequent event as only 13 isolates representing 4 MIRU-VNTR types, were assumingly epidemic
ABSTRACT
Tuberculosis [TB] is a disease caused by a bacterium called Mycobacterium tuberculosis. M. tuberculosis has different molecular weight secreted antigens. Low molecular weightproteinssecreted into the culture medium by M. tuberculosisare thought to play an important role in the development new TB diagnostic tests and new vaccines against tuberculosis. In this report, we describe isolation and purification of low-molecular-weight proteinssecreted by M. tuberculosis. Initially by biphasic medium, bacteria from Lowenstein-Jensen solid medium transferred to a Dorset-Henley liquid medium and After 6 weeks of growth, the bacteria with a 0.22 micron filters of liquid medium containing secreted proteins were isolated and the secreted proteins was precipitated by ammonium sulfate. Protein concentrations were determined by using the lowry protein assay. Then low molecular weight proteins were purified by Sephadex-G75 gel chromatography and we studied purification of low molecular weight proteins by Coomassie-Blue stained SDS-PAGE. The results showed that low molecular weight secreted proteins purified from M. tuberculosis strain DT. Also, low molecular weight proteins made up approximately 65.3% of total proteins. This study demonstrated that without break down of bacteria bodies can be purified low molecular weight secreted proteins from M. tuberculosisliquid medium by Sephadex-G75 gel chromatography
ABSTRACT
The tuberculin skin test is the most commonly used test for diagnosing tuberculosis [TB] infection. The basis of tuberculin testing is the induction of a delayed hypersensitivity reaction to the intradermal injection of tuberculin. Unfortunately, this test is incapable of distinguishing Mycobacterium tuberculosis infection from Bacille Calmette-Guerin [BCG] vaccination or infection with non-tuberculous mycobacteria. The aim of this study is to evaluate the relative potency of human tuberculin skin test] produced by Razi Vaccine and Serum Research Institute [in the guinea pigs sensitized with M. tuberculosis, M. bovis BCG and M. avium. For skin test, different groups of guinea pigs were sensitized with M. tuberculosis, M. avium and M. bovis BCG. Guinea pigs were injected intradermally with 0.1 ml of 0.4, 2 and 10 micro g/ml of tuberculin. Skin reactions [diameters of erythema, in millimeters] were independently measured 24 h after injection and results were calculated. The results showed that the specificity index of human tuberculin test for guinea pigs sensitized with M. bovis BCG in compare of guinea pigs sensitized with M. tuberculosis was equal and for guinea pigs sensitized with M. avium was not equal. This study demonstrated that human tuberculin test produced by Razi Institute for diagnosis of latent infection to M. tuberculosis has lower specificity for M. bovis in comparison with M. avium