Morassa Farnad - Razi Vaccine and Serum Research Institute, Islamic Azad University, Shahre Kord branch
Keyvan Tadayon - Razi Vaccine and Serum Research Institute
Nader Mosavari - Razi Vaccine and Serum Research Institute
Hassan Momtaz - Islamic Azad University, Shahre Kord branch

Background and Aim:Tuberculosis (TB), caused by the Mycobacterium tuberculosis complex (MTBC), is a serious infection in humans and animals. Iran is one of the countries with the highest burden of TB. However, limited information is available on the genotypic characteristics of M. tuberculosis strains infecting humans. The objective of the present study was to characterize the mycobacterial species isolated from pulmonary TB patients using molecular typing.Methods:A cross-sectional study was conducted on 20 patients with smear-positive pulmonary TB, using Ziehl Neelsen staining and bacteriological culturing. DNA was extracted from the isolates by the van Solingen method. Molecular characterizations of the mycobacterial isolates were performed by polymerase chain reaction (PCR)-16SrRNA, PCR-IS6110, and RD-typing with primers RD1, RD4, RD9, and RD12, respectively.Results:The proportion of culture positivity was 100% (20/20). Out of 20 isolates, only one isolate appeared negative in IS6110-PCR and was considered nontuberculosis complex. All isolates except one from Alborz Province appeared positive for Mycobacterium tuberculosis. Based on the obtained results, all isolates except one were identified as M. tuberculosis. The only negative isolate appeared 97% similar to Mycobacterium sp. (Mycobacterium neoaurum).Conclusion:This study confirmed the presence of known M. tuberculosis strains and revealed new strains circulating in Alborz province of Iran.Accurate identification of Mycobacterium isolates has great importance for proper and immediate treatment of TB patients.

16S rRNA; IS6110, Mycobacterium tuberculosis complex; RD typing