Virulence factors and mechanisms of Aeromonas hydrophila infection in catfish Siluriformes: a review and bibliometric analysis

Aeromonas hydrophila, a gram-negative bacterium belonging to the Aeromonadaceae family, has significantly impacted global catfish production within the Siluriformes family, resulting in economic losses. Despite being recognized as part of the normal flora found in water systems and fish organs, the pathogenicity of A. hydrophila is often activated by the expression of virulence genes encoding toxins. To systematically gather reliable scientific studies on the virulence of A. hydrophila in catfish Siluriformes, the PRISMA method was employed, utilizing the Scopus database. Following the application of inclusion and exclusion criteria, a total of 66 documents were scrutinized, and a bibliometric analysis was conducted using VOSviewer. Based on the keyword analysis, aerolysin toxin emerged as the most prevalent virulence factor, appearing in 64% (n = 42) of the papers, followed by hemolysin, enterotoxin, and biofilm. The analysis also revealed that the primary organs associated with infection were the kidney and liver, recognized as immune secretion organs, followed by the gills, intestine, skin, and mucus, identified as entry points. The major clinical signs of A. hydrophila infection included hemorrhage, lesion, ulceration, and septicemia. This study elucidates the scientific consensus on the infection mechanisms of A. hydrophila, covering entry points, adherence, and invasion. The ranked entry points and virulence factors identified herein offer valuable insights for designing novel treatments or preventive measures in catfish farming

Isolation and identification of fungi associated with diseased freshwater fishes in Terengganu, Malaysia

Fish health problem presents an ongoing challenge for aquaculture as disease outbreaks cause fish mortalities and financial losses. This study investigated the fungal infections in common freshwater ornamental and food fish species in Terengganu, Malaysia. Diseased gold gourami (Trichopodus trichopterus), snakeskin gourami (Trichogaster pectoralis), angelfish (Pterophyllum scalare), African sharptooth catfish (Clarias gariepinus), and red hybrid tilapia (Oreochromis spp.) with dermal lesions were sampled for fungal isolation. A total of 12 fungal isolates were isolated, and characterized by macro- and micro-morphologies of colonies. Isolates were identified by sequence analysis of ribosomal internal transcribed spacer (ITS) region. Genera Aspergillus, Geotrichum and Pestalotiopsis were more prevalent than Flavodon, Pseudopestalotiopsis, Trichoderma and Apiotrichum (Trichosporon). This study indicated the advantage of good hatchery settings and management practices in reducing fungal infections