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Abstract Background and objectives: Tuberculin is the proteins existed in tuberculosis culture medium which precipitated by trichloroacetic acid (TCA) or ammonium sulfate. Tuberculin is used for diagnosis of Tuberculosis. The aim of this study is to compare the human tuberculin produced by Razi Institute and Mycobacterium tuberculosis Culture Filtrate Protein. Material and Methods: Initially By biphasic medium, Bacteria from Lowenstein–Jensen solid medium was transferred to a Dorset−Henley Liquid medium. After 6 weeks of growth, the bacteria were isolated from liquid medium containing secretory proteins by the 0, 22 micron filter and the solution containing secretory proteins was precipitated by TCA and ammonium sulfate, separately. Then, using spectrophotometer and kjeldahl protein assay, the presence of protein in solution was confirmed. At the end, the precipitated proteins are compared with the human tuberculin by Coomassie-Blue stained SDS-PAGE Results: The protein samples precipitated by TCA have more bands in the limit of higher than 20 kDa, but the protein samples by ammonium sulfate have more bands in the limit of less than 20 kDa. Human tuberculin proteins are like smear and their weight is less than 16 kDa. Conclusion: It seems that ammonium sulfate is more suitable for low molecular weight proteins than TCA for precipitation. Key words: Mycobacterium tuberculosis, SDS-PAGE, tuberculin

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Abstract Background and Objective: A high level of homogeneity observed within all bacteria in the Mycobacterium tuberculosis complex makes a property that seriously challenges traditional biochemical-based identification methods of these pathogens in the laboratory. The work presented here was conducted to characterize Mycobacterium tuberculosis complex isolates in Golestan, Northern Iran. Material and Methods: Between 2008 and 2010, 42 mycobacterial isolates were collected from clinical tuberculosis-suspected patients in Golestan province. The isolates were sub-cultured on fresh Mycobacterium-specific culture media including glycerinated and pyruvated Lowenstein-Jensen slopes. The isolates were subsequently subjected to a PCR-based identification scheme coined Huard-Warren method. This strategy consisted of three individual algorithms namely, 16SrRNA RV typing (Rv0577, Rv3877.8, Rv1970, Rv3120, Rv1510 and IS1561) and RD typing (RD1, RD 4, RD9 and RD12). Results: All isolates were proved to be M. tuberculosis. Furthermore, none of the patients were being infected with any other member of the M. tuberculosis complex or simultaneously co-infected with two mycobacteria. This fundamental observation was independently obtained by specific culture media, RV typing and also RD typing. Conclusion: Considering the fact that cattle and sheep farming play an important role in the economy of the region, absence of Mycobacterium bovis in the studied isolates can be unexpected to some extent. Huard-Warren which is a simple and cost-effective identification method can be used in both reference and regional laboratory for differential diagnosis of tuberculosis. Keywords: Mycobacterium Tuberculosis Complex, Huard-WarrenMethod, 16SrRNA, Golestan Province, RD Typing, RV Typing

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