Isolation, identification and determination of the drug resistance in Tabriz aquarium fish mycobacteria

Fish mycobacteriosis is a chronic progressive disease that caused by different species of mycobacteria. Diagnosis of the disease in ornamental fish is usually done by bacterial culture and histopathology. Identification is also based on the rate of growth at different temperature, the pigmentation type, the morphology of colony and by biochemical tests. Although the primary diagnosis of fish mycobacteriosis is based on clinical symptoms and the presence of granuloma in visceral tissues by sampling, but in some cases no any clinical symptoms or no granulomas masses are seen. Due to the zoonotic character of the disease, increasing importance of aquariology, and also increasing of opportunistic infections via Non-tuberculous mycobacteria in older persons or immunocompromised patients, also existence of some extremely difficulties to treat like to require the long course of therapy, and on the other hand, the financial losses, so; the present study planned to detection and identification of mycobacterial species in aquarium fish. Existence of Mycobacterial species in 53 fishes were investigated that they were obtained from some local aquarium shops in Tabriz by Ziehl-Neelsen staining and culture on Lowenstein-Jensen (LJ) medium. Identification of isolates was done by morphological characters of mycobacteria on LJ and using of biochemical tests. For drug susceptibility testing, the proportional method on LJ were used for isoniazid, ethambutol, rifampin, streptomycin, kanamycin, ciprofloxacin, and amikacin. The susceptible (H37Rv) standard Mycobacterium tuberculosis strain was used as a control. Acid-fast bacilli were detected on the 7 smears of samples by direct microscopic examination of Ziehl-Neelsen. In using of the culture method, Mycobacterium spp. were isolated from 28.3% of the fishes. The isolated species were identified as M. marinum, M. fortuitum, M. smegmatis, M. terrea, M. flavescens and M. asiaticum. The study showed that M. fortuitum and M. marinum are more than other species. In the drug susceptibility testing; the streptomycin had the highest resistance (93.33%) and the lowest drug resistance was diagnosed to ciprofloxacin (20%). In the investigation, Mycobacterium marinum, M. fortuitum, M. smegmatis and M. flavescens that are well known as pathogens in fish and humans were isolated, which were resistant to most drugs that are used in the treatment. Therefore, more attention should be paid to the presence of
mycobacteria in aquarium fish for reducing the rate of bacterial transmission to human.