An environmentally safe phage-based strategy for controlling bacterial infections in cultured freshwater fish species

Author: Sophiko Sturua
Co-authors: Sopiko Sturua
Keywords: Aquaculture, Bacteriophages
Annotation:

The aquaculture industry has been expanding significantly worldwide in the past decades. In 2018, the total fish production, trade, and consumption reached an all-time record equaling 114.5 million tons in live weight [1]. Aquaculture is one of the fastest growing and developing sectors in South Caucasus region, including Georgia. The rRainbow trout is the most common cultured fish species in Georgia, comprising 61% of the total fish production [2]. One of the main challenges for the development of aquaculture worldwide and also in Georgia are bacterial infections that may lead to massive deaths in fish and, correspondingly, to big large financial losses. Efforts to keep farmed fish free of disease are important for both fish welfare and fish farmers. The problem related to occurrence and spread of infections is especially acute for fish hatcheries and larvae producing facilities, and also juvenile fish ponds, where mortality rates usually are significantly higher compared to adult fish. The freshwater fish bacteriosis in the natural environment as well asand in fish farms is mainly caused by a number of Aeromonas species [3]. Aeromonas. hydrophila, a Gram-negative, rod-shaped facultatively anaerobic bacterium, is a natural inhabitant of fresh and brackish waters. Aeromonas. hydrophila frequently causes disease outbreaks in wild and cultured fish leading to Aeromonas septicemia and ulcerative infections [4]. The recent studies have reported isolation of multidrug resistant (MDR) A. hydrophila from diseased fish and aquatic systems worldwide [5,6]. Various antimicrobials chemicals, dyes, and antibiotics have been used in aquaculture for treatment of sick fish as well asand for prevention of bacterial infections. Use of antibiotics to control fish bacteriosis, including Aeromonas infections, is still a the most widely used approach that guarantees reduction in morbidity and mortality, and contributes to significant advances in the health of the population. The public health hazards related to use of antimicrobials in aquaculture include development and spread of antimicrobial-resistant (AMR) bacteria and resistance genes, as well asalong with the presence of antimicrobial residues in aquaculture products and the environment [7]. The rising drug resistance among aquatic bacteria and adverse effects of antibiotics lead to a common understanding that use of antibiotics for prevention of fish diseases should remain low and should n’t not be a primary treatment option in fish farming practices [8]. Biological control of diseases, including phage therapy and prophylaxis, is currently considered as a best approach for aquaculture [14,15].