Pathogenic mechanisms of Aeromonas hydrophila and the protective role of probiotics in sustainable aquaculture.

Aeromonas hydrophila (A. hydrophila) is a pervasive opportunistic fish pathogen responsible for hemorrhagic septicemia and gastrointestinal disease and, together with other motile aeromonads (e.g., A. veronii, A. caviae, and A. dhakensis), for motile aeromonad septicemia (MAS), which cause significant economic losses in the global freshwater aquaculture industry. The widespread use of antibiotics to control A. hydrophila has led to increased antimicrobial resistance and environmental concerns, necessitating the urgent need for sustainable alternative treatments. We systematically retrieved, screened, and selected relevant studies from three databases: Scopus, Web of Science, and PubMed. Articles published between January 1, 2016, and June 1, 2026, were included. Two reviewers independently assessed the eligibility and data quality and extracted information from the identified articles. We performed a bibliometric analysis using VOSviewer and RStudio for visualization. We identified 339 experimental research publications from 2016 to 2026 and selected 39 articles that met the selection criteria for full-text evaluation. For VOSviewer keyword co-occurrence networking, we used the 277 Scopus publications (research articles, reviews, and book chapters) retrieved with the same search string. For the country trend analysis, we used the 464 deduplicated records (research articles, reviews, and book chapters) screened after duplicate removal. The most current keywords used were A. hydrophila, probiotic agents, microbiology, and probiotics. The country trend analysis revealed a remarkable increase in publications over the past 10 years, with key contributions from China, India, Iran, Brazil, and Egypt. The year 2025 recorded the highest publication output over the past 10 years. A diverse repertoire of virulence factors, including act, aerA, fla, ahyI, ahyR, and type III secretion systems, mediates A. hydrophila pathogenicity. Probiotics exert consistent multimodal protection via competitive pathogen exclusion, production of antimicrobial compounds, intestinal barrier enhancement, and host immunomodulation. Probiotics improve growth performance, digestive enzyme production, nutritional composition, immune response, hematology and histopathology, gut microbiome, and survival. This review highlights that probiotics are a viable, evidence-based component of integrated health management programs for A. hydrophila control, complementing rather than universally replacing antibiotics. This review highlights that probiotics are viable, evidence-based, and sustainable alternatives to antibiotics for A. hydrophila control.