PCR-RFLP Based Detection of atypical Mycobacteria Isolated from Aquatic Environment

Non-tuberculous mycobacteria (NTM) serve as the causative agent for fish tuberculosis which is a chronic progressive disease covering a vast range of cultured and wild, freshwater and marine environments in different climatic conditions. Detection of environmental Mycobacteria in a conventional way is generally dependent on the basis of phenotypic, histopathological and biochemical characterization. The present study focused on the distribution and occurrence of mycobacterial pathogens in clinically infected fishes of a variety of species, water and soils from different aquaculture sources in West Bengal, India. Samples were collected from four distinct regions where fishes were examined for granulomatous inflammation. A total of 161 fishes, 127 water and 97 soil samples were examined and 132 (81.98 %), 65 (51.18 %) and 36 (37.11 %) appeared as acid-fast positive respectively. Presences of acid-fast bacteria within necrotic tissue of infected fishes were detected by Zn staining. Morphology, biochemical characteristics and 16S rRNA gene sequencing of bacteria were satisfactory to show the acid-fast bacilli belong to the Genus Mycobacteria. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was carried out to analyze the rpoB gene sequencing to confirm Mycobacteria down to the species level. Ten different NTM species were identified using PCR-RFLP analysis. Mycobacterium fortuitum type I was the most abundantly isolated species among all the sample sources. The present study suggests that water play a major role in the epidemiology of environmental Mycobacteria, infecting aquatic organisms and conducting potential public health hazard, especially those who are immune-compromised individual.