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Updated: Aug 6, 2026
Modeling Tuberculosis in Mycobacterium marinum Infected Adult Zebrafish
Published on: October 8, 2018
Pathogenesis of Mycobacterium spp. in zebrafish (Danio rerio) from research facilities
Virginia Watral1, Michael L Kent
1Center for Fish Disease Research, Department of Microbiology, Oregon State University, Corvallis, OR 97331-3804, USA.
Abstract:
One of the most common diseases that we have diagnosed in zebrafish is mycobacteriosis, caused by several Mycobacterium spp. The severity of the disease ranged from severe outbreaks to incidental infections. We conducted an in vivo study to evaluate the pathogenesis of six isolates of Mycobacterium from zebrafish with mycobacteriosis from four research facilities and one wholesale supplier of zebrafish in the United States: Mycobacterium abscessus, Mycobacterium peregrinum, Mycobacterium chelonae (2 isolates), and Mycobacterium marinum. We also included two isolates of M. marinum from other fishes. Fish were exposed by intraperitoneal injection at a target does of 5 x 10(4) bacteria/fish, and were held in static aquaria at 28 degrees C for 8 weeks. Fish were examined by histology and culture, and mortalities were recorded. The M. marinum isolates caused 100% infection and mortality between 30% and 100%. None of the other Mycobacterium species caused significant mortalities, but several of these fish had granulomatous lesions in visceral organs. Mycobacteria were consistently recovered in culture from fish exposed to M. marinum, and from only 9% of fish exposed to the other species. This study suggests that, of the isolates tested, only M. marinum is highly pathogenic and virulent to healthy zebrafish.
Insights
Mycobacterium marinum causes severe mycobacteriosis and mortality in zebrafish. Other Mycobacterium species tested caused few deaths but did lead to granulomatous lesions, indicating M. marinum is the primary pathogen.
Area of Science:
- Aquatic animal health
- Fish pathology
- Microbiology
Background:
- Mycobacteriosis is a common disease in zebrafish, impacting research integrity.
- Several Mycobacterium species can cause infections, with varying severity.
Purpose of the Study:
- To evaluate the pathogenicity and virulence of different Mycobacterium isolates in zebrafish.
- To identify which Mycobacterium species pose the greatest risk to zebrafish health.
Main Methods:
- Six Mycobacterium isolates from zebrafish and two M. marinum isolates from other fish were used.
- Zebrafish were exposed via intraperitoneal injection, and monitored for 8 weeks.
- Histology, culture, and mortality recording were employed for assessment.
Main Results:
- Mycobacterium marinum isolates caused 100% infection and significant mortality (30-100%).
- Other Mycobacterium species resulted in minimal mortality but caused granulomatous lesions.
- Mycobacteria were consistently cultured from M. marinum-exposed fish, but rarely from others.
Conclusions:
- Mycobacterium marinum is highly pathogenic and virulent to healthy zebrafish.
- Other tested Mycobacterium species are less virulent but can still cause disease manifestations.
