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Abstract Background and objectives: With almost nine million new cases each year, tuberculosis is still one of the most Life-threatening diseases in the World. Distribution of drug resistant strains of M.tuberculosis has a lot of importance. This research was carried out to determine the frequency of drug resistance of M. tuberculosis in strains isolated in Golestan province. Material and Methods: In this cross -sectional study, 104 isolate of M.tuberculosis which isolated from patients referred to Gorgan tuberculosis Health Center, in 2008 were studied. DNA was extracted by Boiling Method. By using PCR method, we determine the M.tubeculosis strain and resistance to Rifampin (Using IS6110 and Gene rpoB primers) and resistance to Isoniazid (Using InhA and KatG primers). As a Gold Standandard, “Proportional method” was performed for 45 Samples. Results: 87 strains were identified as M.tuberculosis. 6.9% of them were resistant to Isoniazid, 4.6% to Rifampin and 2.3% to both (MDR).Sensitivity and Specifity of PCR method in detection of resistant to Isoniazid were 95.3% and 57.1% and for Rifampin were 94.7% and 33.3%. Conclusion: We found that in our region, the MDR is not very common. More than 16% of isolated strains from tuberculosis suspected patients were MOTT, for this reason it is necessary to mention that use biochemical or PCR method to determine M.tuberculosis is necessary. Key words: Mycobacterium tuberculosis, MDR, PCR, Proportional method , Golestan province.

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Abstract Background and objectives: Identification and monitoring of multidrug-resistant Mycobacterium tuberculosis strains (MDR) is highlighted by the high risk of their spreading in different areas. Prevalence of these strains was evaluated in Golestan province in northeast of Iran. Material and Methods: Drug susceptibility testing to Isoniazid and rifampin was carried out for 148 clinical samples that had grown in Mycobacteria growth indicator tube (MGIT) system, according to the manufacturer's instructions (Becton-Dickinson, USA). The association of drug resistance frequency with demographic characteristics and growth time were investigated. The appropriate statistical tests, X2 and student T- test were performed for comparison of these variants. A p value>0.05 was considered significant in all cases. Results: The turnaround time required for growth of Mycobacterium tuberculosis in MGIT system was between 2 to 55 days (mean 16.3±10.4 days). Of all samples studied, 17.6% and 3.4% were resistant to Isoniazid and rifampin, respectively, and 3.4% (5 samples) were MDR (CI 95% 1-6%). The turnaround time required for determining MDR cases was 9.6 days. No statistically significant association was found between the resistance to the drugs and none of the factors including sex, age, type of clinical sample, and positivity of the smear. Conclusion: The prevalence of MDR in the studied region was determined to be 3.4% which is similar to the country-wide evaluations. The turnaround time for Mycobacterium growth and anti drug susceptibility result can be shortened by MGIT method. Key words: Mycobacterium tuberculosis, Mycobacterium Growth Indicator Tube, Multidrug Resistant

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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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Background and objectives: Tuberculosis (TB) is a serious public health problem and a significant diagnostic and therapeutic challenge worldwide. Molecular diagnostic techniques are crucial parts of the World Health Organization’s new tuberculosis control strategy. This study aims to identify Mycobacterium tuberculosis and rifampin resistance in pulmonary and extra-pulmonary clinical specimens using the Gene Xpert MTB/RIF assay.
Methods: The study was carried out on 220 specimens from pulmonary and extra-pulmonary TB patients that were sent to the Kavosh Laboratory in Gorgan (Iran) during 2018-20. The Gene Xpert MTB / RIF method was applied to detect M. tuberculosis and rifampin resistance.
Results: Of 220 specimens, 15 (6.81%) were found to be positive, four (26.6%) of which were related to pulmonary and 11(73.3%) to extra-pulmonary specimens. None of the positive samples was resitant to rifampin according to assay.
Conclusion: Our findings demonstrate that the Gene Xpert MTB/RIF is able to accurately detect M. tuberculosis in pulmonary and extra-pulmonary specimens. The accurate and early diagnosis of TB infection allows timely therapeutic intervention, which is beneficial not only for the patient but also for possible contacts.

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Background-COVID-19 pandemic started in March 2020 and though cases are reported till now, major cases were seen till January 2022. During this pandemic,the whole healthcare system was diverted into COVID-19 patient care. Both Tuberculosis (TB) and COVID-19 are diseases of respiratorysystem, and it is important to study impact of COVID-19 on Tuberculosis. The main objective of study is- To detect the M.tuberculosis and rifampicin resistance before, during and after COVID-19 restrictions were fully released.
Material and methods- Pulmonary and extra pulmonary samplesfrom 1^st January 2018 till 31^st December 2022(five years) were included in the present study. The period was divided as-
2018,2019 – BeforeCOVID-19
2020,2021 –COVID-19 period with restrictions (such as use of masks, social distancing, avoiding gatherings)
2022 –COVID-19 period without restrictions. 
All samples received in Tuberculosis section were subjected to CBNAAT. Samples were processed according to manufacturer’s guidelines.
Results- There was no significant difference in samples received per year from 2018-2022. The positivity of M.tuberculosis decreased from 22.52%in pre-COVID-19 period to 15.70% in COVID-19 period with restrictions and increased again in 2022(16.80%). Rifampicin resistance was also decreased from10.40% to 6.89% in COVID-19 period with restrictions.  Decrease in positivity was not observed in Extrapulmonary tuberculosis cases.
Conclusion –Restrictionsimposed during COVID-19 period could decrease Tuberculosis as well as rifampicin resistance. Thus implication of restrictions for TB suspected and positive patients on regular basis can help in preventing spread of the disease.