Morphology and distribution of granulomatous inflammation in freshwater ornamental fish infected with mycobacteria

Abstract

Mycobacteriosis in fish is a chronic progressive ubiquitous disease caused by Mycobacterium marinum, M. gordonae and M. fortuitum in most cases. The aim of this study was to describe the morphology and distribution of lesions in 322 freshwater ornamental fish across 36 species. Granulomatous inflammation was diagnosed by gross examination and histopathology testing in 188 fish (58.4%); acid-fast rods (AFR) were determined in only 96 (51.1%) fish from 19 species after Ziehl-Neelsen staining. The most often affected organs with AFR were the kidney (81.2%), digestive tract (54.1%), liver (48.2%), spleen (45.9%) and skin (21.2%); sporadically, AFR were found in the branchiae (9.4%) and gonads (4.7%). In 14 randomly selected fish originating from four different fish tanks, the distribution of mycobacterial infection was studied by culture examination of the skin, gills, muscle tissue, digestive tract, liver, spleen and kidney. In 12 fish, the species M. marinum, M. gordonae, M. fortuitum, M. triviale, and M. avium subsp. hominissuis (serotypes 6 and 8 and genotype IS901- and IS1245+) were detected; mixed infection caused by different mycobacterial species was documented in five of them.

Fish: a potential source of bacterial pathogens for human beings

“…Mycobacteriosis of aquarium fish in the Czech Republic is one of the most commonly diagnosed bacterial diseases (Navratil et al, 2000;Novotny et al, 2004). Gross changes may include emaciation, ascites, exophthalmos, and keratitis, changes in pigmentation and skin ulcerations (Wolf and Smith, 1999).…”

Occurrence and antimicrobial susceptibility of Mycobacterium peregrinum in ornamental fish

“…In this study, in fish which revealed no visible pathomorphological granulomatous changes, the mycobacteria were found through direct microscopy and bacteriological exami-nation. Severe systemic mycobacteriosis without typical granuloma formation was diagnosed by Yanong et al (32) in a group of six mature captive striated frogfish (Antennarius striatus), and by Novotny et al (21) in three-spot gourami (Trichogaster trichopterus). The presence and distribution of mycobacterial species in clinically healthy aquarium fish and their environ-ment has been also noted by Beran et al (5) and Zanoni et al (33).…”

“…Fish mycobacteriosis is well-recognised in marine and freshwater fish, with several reviews concerning the topic (6,7,12 (1,7,13,32). Environmental mycobacteria can be pathogenic to a variety of freshwater and marine fish species both in the wild and kept in captivity (15,21) (3,13,20,22,29). Clinical signs of fish mycobacteriosis are quite variable and usually include loss of appetite, lethargy, staying alone in the corner of the aquarium, floating on the surface of the water, anorexia, skin discoloration, open lesions, ulcerations, unilateral or bilateral exophthalmia, emaciation, skeletal deformities, and well-demarcated granulomas in internal organs (7,25).…”

A case of opportunistic skin infection with Mycobacterium marinum during adalimumab treatment in a patient with Crohn's disease

“…Human infection may be caused by direct injury by fish fins or occur after a cutaneous trauma and exposure to contaminated water. 11 Due to its low culture temperature and inhibition of growth at 37°C, the infection is mostly limited to the skin, though it may also reach deeper structures. 12 The mean incubation period is 7 months.…”