Causative Agents of Mycobacterial Diseases in Aquarium Fish and their Importance for Human Health

Introduction: The isolation of Non-Tuberculous Mycobacteria (NTM) from human and fish mycobacteriosis specimens increasingly has turned to be a major concern. NTM can cause opportunistic infections in elderly and immunocompromised patients; it is not only difficult to treat but also requires long course of therapy. Aim: To isolate and identify the species of non-tuberculous mycobacteria in aquarium fish and to study the importance of their opportunistic infections to the general health of society. Materials and Methods: Fifty-three common freshwater aquarium fish were included in the study for the diagnosing of mycobacteria by culture and Ziehl-Neelsen staining methods. The Mycobacteria species were identified by morphological characteristics of colonies and biochemical tests. Drug susceptibility tests were also performed using the proportional method on Lowenstein-Jensen media. Results: Among 53 ZN-stained specimens, 13.2% gave positive direct microscopic results for mycobacteria. Using the bacterial culture method, Mycobacterium spp.colonies was observed in 28.3% Lowenstein-Jensen agar tubes. Identification of different species of mycobacterium from 15 isolates obtained by culture based on phenotypic characteristics and biochemical tests was as follows: M. fortuitum, 6 cases; M. marinum, 3 cases; M. smegmatis, 3 cases; M. terrea, 1 case; M. flavescens, 1 case; and M. asiaticum, 1 case. The resistance rates of isolates were 93.33%, 80%, 80%, 66.66%, 60%, 40% and 20% against streptomycin, isoniazid, rifampin, ethambutol, kanamycin, amikacin and ciprofloxacin, respectively. Conclusion: In this study, some isolated mycobacteria which have been considered as potential pathogens in fish and humans were identified, such as Mycobacterium marinum, M. fortuitum, M. smegmatis and M. flavescens. All of them were found to be resistant to the most of tested drugs. It's important to be aware of the contamination of some aquarium fishes with mycobacteria species to reduce the risk of bacterial transmission to humans.