Recent Insights into Aeromonas salmonicida and Its Bacteriophages in Aquaculture: A Comprehensive Review

Abstract

The emergence and spread of antimicrobial resistance in pathogenic bacteria of fish and shellfish have caused serious concerns in the aquaculture industry, owing to the potential health risks to humans and animals. Among these bacteria, Aeromonas salmonicida, which is one of the most important primary pathogens in salmonids, is responsible for significant economic losses in the global aquaculture industry, especially in salmonid farming because of its severe infectivity and acquisition of antimicrobial resistance. Therefore, interest in the use of alternative approaches to prevent and control A. salmonicida infections has increased in recent years, and several applications of bacteriophages (phages) have provided promising results. For several decades, A. salmonicida and phages infecting this fish pathogen have been thoroughly investigated in various research areas including aquaculture. The general overview of phage usage to control bacterial diseases in aquaculture, including the general advantages of this strategy, has been clearly described in previous reviews. Therefore, this review specifically focuses on providing insights into the phages infecting A. salmonicida, from basic research to biotechnological application in aquaculture, as well as recent advances in the study of A. salmonicida.

Keywords: Aeromonas salmonicida; antimicrobial resistance; bacteriophage; salmonid culture.

Fig. 1. Characteristics of A. salmonicida subsp. salmonicida (A and B) and its clinical features in salmonid fish (C).

(A) Notable brown pigmentation of typical A. salmonicida (A. salmonicida subsp. salmonicida strain AS01 [25]) cultured at 20°C in tryptic soy agar. (B) Transmission electron micrograph of A. salmonicida subsp. salmonicida strain AS01 [25] negatively stained with 2% uranyl acetate (Zeiss TEM EM902 (Zeiss), 80 kV). (C) Distinct clinical symptoms of furunculosis caused by A. salmonicida subsp. salmonicida strain AS01 [25] in experimentally infected rainbow trout (O. mykiss). Black and red arrows indicate the notable features of furuncle-like swellings and ulcerative lesions in infected fish, respectively.