Molecular identification, genetic diversity, and antibiotic resistance of pathogenic bacteria in finfish aquaculture systems of southwestern Bangladesh

Bacterial disease outbreaks continue to threaten finfish aquaculture in southwestern Bangladesh, resulting in significant economic losses and heightened food security concerns. To address the absence of robust molecular diagnostics and genetic diversity assessment for bacterial pathogens, a comprehensive five-year study (2018-2023) was conducted to evaluate pathogen prevalence, genetic diversity, and antibiotic resistance, with the goal of informing region-specific management strategies. A total of 340 fish, representing 17 species from 10 districts, were systematically collected from farms, hatcheries, nurseries, and markets. Specimens underwent phenotypic and biochemical characterization, followed by DNA extraction and quantification under stringent quality control protocols. Quantitative PCR (qPCR) utilizing species-specific primers, including the 16S rRNA housekeeping gene, enabled sensitive detection and quantification of bacterial loads. Statistical analyses included…