Investigation of Potential Reservoirs of Non-Tuberculous Mycobacteria in a European Sea Bass (Dicentrarchus labrax) Farm

Davide Mugetti,Paolo Pastorino,Katia Varello,Marino Prearo,Vasco Menconi,Mattia Tomasoni,Alessandro Dondo,Elena Bozzetta

doi:10.3390/pathogens10081014

Davide Mugetti, Paolo Pastorino + Show 6 more

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https://doi.org/10.3390/pathogens10081014

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Abstract

Fish mycobacteriosis is a widespread global problem caused by species of non-tuberculous mycobacteria (NTM). Mycobacterium marinum is one of the species most often involved in disease episodes of aquarium and farmed fish. Since there is currently no available effective therapy or vaccine, a prompt search for routes of entry is key to limiting the damage induced by the disease. Here we report a case of mycobacteriosis follow up in a European sea bass (Dicentrarchus labrax) farm located in Northern Italy, in which environmental samples and newly added fish batches were analyzed. Samples from fish present on the farm, sediment, and periphyton all resulted positive for M. marinum, whereas the new fish batches and the water samples resulted negative. The environmental resistance of NTM (alcohol-acid resistance, biofilm formation) and the lack of prophylactic and therapeutic strategies make these diseases difficult to manage. Prompt identification of biotic and abiotic reservoirs, combined with good zootechnical hygiene practices, are the most effective measures to control fish mycobacteriosis in intensive farms.

Highlights

Fish mycobacteriosis is a complex of infectious diseases caused by bacteria of the Mycobacteriaceae family [1]
The best-known species of the genus Mycobacterium (Mycobacterium tuberculosis, M. leprae) are human pathogens and do not cause fish mycobacteriosis; most other species cause disease in fish. These mycobacteria do not cause tuberculosis; they are generally identified as non-tuberculous mycobacteria (NTM) [4]: the best known NTM that cause disease in fish is M. marinum [5]
Fish mycobacteriosis is a troublesome problem for fish farms, especially for salt-water farms [8]

Summary

Introduction

Fish mycobacteriosis is a complex of infectious diseases caused by bacteria of the Mycobacteriaceae family [1]. The best-known species of the genus Mycobacterium (Mycobacterium tuberculosis, M. leprae) are human pathogens and do not cause fish mycobacteriosis; most other species cause disease in fish. These mycobacteria do not cause tuberculosis; they are generally identified as non-tuberculous mycobacteria (NTM) [4]: the best known NTM that cause disease in fish is M. marinum [5]. This photochromogenic bacterium produces smooth to rough yellow colonies on Löwenstein–Jensen medium after incubation for 7 or more days (slow-growing) [6]. M. marinum can infect fresh and salt-water fish species [7,8]

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