Identification of Nontuberculous Mycobacteria Species Isolated from Water Samples Using Phenotypic and Molecular Methods and Determination of their Antibiotic Resistance Patterns by E- Test Method, in Isfahan, Iran

Introduction Many studies have shown epidemiological links between strains isolated in tap water, and those isolated from patients. Molecular methods linked to PCR are more reliable and faster for identification of             non- tuberculous mycobacteria(NTM). In this study molecular methods were used for identification and typing of NTM. Materials and Methods Five hundred ml of ۸۵ water samples was passed through ۰.۴۵ μm filters. The filters were transferred directly onto ۷H۱۰ Middle Brook solid media, containing ۱۵% OADC. PCR for ۱۶S rRNA was done and the PCR product (۱۵۰۰ bp) was sequenced. PRA of the hsp۶۵ gene was investigated to identify the species of isolates. For evaluation of susceptibility of NTM to antimycobacterial agents, E-test method was used. Result The genus of ۲۶ isolated NTM was confirmed by ۱۶s rRNA sequence based method. Nineteen isolates of Mycobacteria were differentiated using hsp۶۵genes PRA. The dominant isolates were M. fortuitum  (۲۶.۷%), M. chelonae like organism(۱۳.۳%) and M. mucogenicum (۱۳.۳%). Seventy one percent of NTM species were resistant to isoniazid, ۶۴% to rifampin, ۵۷% to ethambutol, ۳۵% to tetracycline, ۱۴ % to azithromycin and ۷.۱ % to amikacin. Conclusion The results showed that E-test method is not a proper technique for antimycobacterial assay because some NTM species are slow in growing and have no growth on Muller Hinton agar. Regarding the ۱۶S rRNA sequence analysis, the identification of isolates was restricted to the genus level, because ۹۹% similarity within ۱۶S rRNA of two isolates may or may not determine the same species.