Isolation-drug resistance profile and molecular characterization of indigenous typical and atypical mycobacteria

One hundred and fifty mycobacterial isolates from different pathological Labs. of Karachi were collected and screened as acid fast. On the bases of phenotypic and biochemical results, it was found that, 58.66% isolates were typical mycobacteria while 41.33% belonged to atypical mycobacteria. The individual percentages of different mycobacterial species include: M. xenopi 35%, M. thermoresistible 19 %, M. terrae complex 6 %, M. marinum 6 %, M. fortuitum 6 %, M. kansasii 25 % and M. tuberculosis 58.66 %. The sensitivity of mycobacterial isolates was determined against 5 first line, 3 second line and 1 third line anti-tuberculosis drugs. The highest number of the isolates (typical and atypical mycobacteria) offered resistance against isoniazid and streptomycin. Clarithromycin was found to be the drug of choice as regards the drug sensitivity in case of atypical mycobacterial isolates. A total of 40 isolates were subjected to PCR based identification and differentiation of 16S rRNA gene(s). Accordingly, 37.5% isolates were identified as typical mycobacteria while 25% were identified as atypical mycobacteria. These findings carry significance because a detailed research based identification (PCR and Multiplex PCR based) regarding indigenous mycobacteria has been reported for the first time in Pakistan. However, both the approaches (conventional and molecular methods) have experimental importance while identifying these organisms.