Distribution of mycobacteria in clinically healthy ornamental fish and their aquarium environment

Abstract

Some mycobacterial species (particularly Mycobacterium marinum) found in aquarium environments may cause chronic diseases in fish and cutaneous infections in humans, the so-called 'fish tank granuloma'. The presence and distribution of mycobacterial species in clinically healthy aquarium fish and their environment has not been adequately explored. The present study analysed the occurrence of mycobacteria in a decorative aquarium (Brno, South Moravia) and in five aquaria of a professional fish breeder (Bohumin, North Moravia). After Ziehl-Neelsen staining, acid-fast rods (AFR) were observed in six (14.3%) and mycobacteria were detected by culture in 18 (42.9%) of 42 tissue samples from 19 fish. Sixty-five samples of the aqueous environment from all six aquaria were examined; AFR were found in 16 (24.6%) and mycobacteria were detected by culture in 49 (75.4%) samples. Forty-one (70.7%) of 58 selected mycobacterial isolates were identified biochemically as follows: M. fortuitum, M. flavescens, M. chelonae, M. gordonae, M. terrae, M. triviale, M. diernhoferi, M. celatum, M. kansasii and M. intracellulare. The clinically important species for humans and fish, M. marinum, was not detected. Mycobacterium kansasii was isolated from one sample of the aquarium environment from North Moravia, which is a region of the Czech Republic with endemic incidence of M. kansasii in water. The incidence of other conditionally pathogenic mycobacterial species in healthy fish and in all investigated constituents of the aquarium environment including snails and crustaceans used for fish feeding, was quite high. Accordingly, mycobacterial species from aquarium environments may serve as a possible source of infection for both aquarium fish and immunodeficient fish handlers.

Pseudoloma neurophilia infections in zebrafish Danio rerio: effects of stress on survival, growth, and reproduction

“…Mycobacteria are common pathogens of zebrafish (Astrofsky et al 2000; Kent et al 2004) and have been found at background levels in previous studies without clinical signs of disease (Beran et al 2006; Harriff et al 2007; Zanoni et al 2008; Whipps et al 2008). We have shown that stress exacerbates mycobacterial infections in zebrafish (Ramsay et al in press).…”

Disseminated Phaeohyphomycosis in Weedy Seadragons (Phyllopteryx Taeniolatus) and Leafy Seadragons (Phycodurus Eques) Caused by Species of Exophiala, Including a Novel Species

“…are commonly found in sea water and likely represent opportunistic invaders or potential members of normal skin flora. 7,43 Although a variety of Gram-negative bacteria were isolated from skin lesions, no species of bacteria was consistently isolated. Cutaneous lesions in the seadragons were often advanced when examined histologically so that a determination as to whether the inciting lesion was bacterial, fungal, or traumatic was not possible.…”

Paramecium caudatum enhances transmission and infectivity of Mycobacterium marinum and M. chelonae in zebrafish Danio rerio

“…It is possible that these two fish had pre-existing background infections, as we have documented minimal background mycobacteriosis in zebrafish at the laboratory providing the fish for the present study (Kent et al 2004, Kent et al 2011). Mycobacterium species capable of causing disease in fish may occur in aquaria in the absence of disease (Beran et al 2006). Indeed, all groups of the fish in this study, including controls that were not deliberately exposed to mycobacteria, exhibited the presence (perhaps colonization) of large amounts of acid-fast bacteria in the intestinal lumen.…”