Identification of Non-Tuberculosis Mycobacterium species in suspected patients to tuberculosis by Line Probe Assay method

Introduction and Objectives: The genus Mycobacterium consists of over 150 species and except than M. tuberculosis complex and M. leper the other species known as Non-Tuberculosis Mycobacterium (NTM). NTM infections are increasing due to increase in immune deficient individuals in population. Isolation and identification of NTMs by conventional methods is time consuming and low efficient. New Molecular methods, such as Line Probe Assay (LPA) are efficient tools for rapid and accurate detection of NTMs. By using this method identification of NTMs can be performed under 14 days and this would be a good progress in treatment of life threating NTMs infections in immune compromised patients. Materials and Methods: Clinical samples including: sputum, BAL, blood, CSF, soft tissue and wound samples from suspected patients to mycobacterial infections were transferred to reference tuberculosis laboratory. Decontamination was performed by Petroff method. Culture was performed on LJ medium and after incubation in 37°c for 10 days. Conventional methods such as pigment production, growth rate, tween 80 hydrolysis, quantitative catalase, nitrate hydrolysis and niacin production were used for identification of NTMs. Bacterial colonies of culture positive samples were collected and suspended in 1x TE buffer. DNA extraction was performed by using DNA extraction kit. LPA was performed according to LPA kit manual. Results: NTMs rate among total samples was 1.1% and totally 40 NTMs isolates were isolated by culture. By using LPA method all of the isolates identified to species level. M. simiae, M. fortuitum, M. kansasii, M. abscessus and M. avium respectively were the most common isolated species. While, Conventional methods results were inaccurate and misleading and for most of the isolates conventional tests were unable to identify the exact species. Conclusion: NTMs infections rate are life threating in susceptible patients and according to similar clinical manifestation of NTMs infection by tuberculosis diagnosis of this infection is very challenging. Conventional laboratory methods are very inaccurate and time consuming for identification of NTM species. LPA method is a reliable and accurate method that can identify exact NTM species in acceptable time.