فضه حیدری - Azad University of Tehran, Tehran, Iran
پریسا فرنیا - Mycobacteriology Research Center (MRC), National Research Institute of Tuberculosis and Lung Disease (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran.
جمیله نوروزی - Dept. of Microbiology, Azad University of Tehran, Iran
احمد مجد - Dept. of Biology, Azad University of Tehran, Iran
الهه تاجالدین - Dept. of Microbiology, Azad University of Jahrom, Jahrom, Iran
محمدرضا مسجدی - National Research Institute of Tuberculosis and Lung Disease (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran
علیاکبر ولایتی - National Research Institute of Tuberculosis and Lung Disease (NRITLD), Shahid Beheshti University of Medical Sciences, Tehran, Iran

Background and Objective: Identification of atypical mycobacterium (Non tuberculosis Mycobacterium NTM) is important because of the worldwide propagation of these organisms. Recently, molecular studies have identified the specific loci for mycobacterium species by DNA - finger printing methods, but these methods are time-consuming and expensive. In this study, in addition to hsp۶۵ PCR-RFLP method, QUB۳۲۳۲ locus was evaluated for differentiation of atypical mycobacterium from mycobacterium tuberculosis complex. Materials and Methods: This study was performed on ۳۷۱ pulmonary and non pulmonary specimens separated from patients with the symptoms of pulmonary tuberculosis (PTB). After the isolation and culturing of mycobacterium strains using the Lowenstein Jensen media, biochemical tests including production of Niacin, Catalase activity, Nitrate reduction, pigment production and growth rate were performed. Drug susceptibility testing was performed by proportional method. DNA extraction was performed by phenol-chloroform method. hsp۶۵ gene was amplified by PCR. Subsequently the amplicons were digested with three restriction enzymes namely AvaII, HphI and HpaII and electrophoresed on ۳% agarose gel. QUB۳۲۳۲ locus was also evaluated for differentiation of atypical mycobacterium and mycobacterium tuberculosis complex. Results: Out of ۳۷۱ isolates, ۳۲ (۸.۶%) were multi-drug resistant TB (MDR-TB), ۱۸۴ (۴۹.۵%) were susceptible and ۱۵۵ (۴۲.۵%) were non MDR (combined resistance) that ۱۵% of MDR cases and ۲۵% of non MDR cases were non tuberculosis mycobacterium. Out of ۳۱ slow growing isolates, ۵۸% were M. simiae and ۱۹% were M. kansasii. The sensitivity of QUB۳۲۳۲ locus for differentiation of the atypical mycobacterium from mycobacterium tuberculosis complex was ۸۰%. From the total of ۴۳ NTM samples, ۱۲ (۲۷.۹%) were rapid growing and ۷۲% were slow growing. Conclusion: QUB۳۲۳۲ locus has the high discriminative power for differentiation of atypical mycobacterium from the mycobacterium tuberculosis complex, therefore, it can be used as a substitute for PCR-RFLP method.

Key words: Atypical mycobacterium, VNTR, QUB۳۲۳۲ locus