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<p>The sustainable expansion of striped catfish (<i>P. hypophthalmus</i>) aquaculture in Egypt is constrained by environmental stressors, recurrent bacterial infections, and rising antimicrobial resistance. This study offers the first integrated assessment of water quality parameters, pathogen identity and virulence, antimicrobial resistance (AMR) patterns, and the immunoprotective potential of dietary <i>S. platensis</i> under Egyptian farming conditions. Field assessments from naturally infected farms revealed chronic hypoxia (mean DO 3.66&#xa0;mg L<sup>−1</sup>) and persistent thermal stress (32.6&#xa0;°C), both significantly outside recommended ranges, while nitrite levels approached the known toxicity threshold. Two major bacterial pathogens—<i>Aeromonas hydrophila</i> and <i>Streptococcus agalactiae</i>—were isolated with comparable prevalences across liver, kidney, and spleen tissues. Molecular characterization (16S rRNA sequencing; GenBank PX371951 and PX371952) confirmed their identity. Probit challenge assays demonstrated markedly higher virulence for <i>A. hydrophila</i> (LD<sub>50</sub> = 1.05 × 10<sup>5</sup>&#xa0;CFU fish<sup>−1</sup>) compared with <i>S. agalactiae</i> (LD<sub>50</sub> = 1.06 × 10<sup>6</sup>&#xa0;CFU fish<sup>−1</sup>). Both species exhibited multidrug resistance, notably universal resistance to penicillin (<i>A. hydrophila</i>) and high resistance to ampicillin, tetracycline, and amikacin (<i>S. agalactiae</i>), underscoring the limitations of empirical antibiotic use. A 4-week feeding trial demonstrated that dietary <i>S. platensis</i> (5&#xa0;g&#xa0;kg<sup>−1</sup>) significantly enhanced innate immunity, reduced stress (lower cortisol) and oxidative damage (lower malondialdehyde), and improved antioxidant enzyme activities (SOD, catalase). <i>Spirulina</i> supplementation reduced mortality by 22.6% after <i>A. hydrophila</i> challenge and by 79.2% after <i>S. agalactiae</i> challenge, demonstrating substantial immunomodulatory and protective benefits. Overall, this work highlights critical environmental stressors and AMR challenges in Egyptian catfish farming and identifies <i>Spirulina platensis</i> as a practical, eco-friendly immunostimulant that can reduce disease burden in striped catfish aquaculture. Overall, this work highlights critical environmental stressors and AMR challenges in Egyptian catfish farming and identifies <i>Spirulina platensis</i> as a practical, eco-friendly immunostimulant that can reduce disease burden in striped catfish aquaculture, suggesting promising avenues for improving disease resilience in health management strategies.</p>

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Enhancing disease resilience in striped catfish (Pangasianodon hypophthalmus): an integrated assessment of environmental stressors, pathogen dynamics, and the protective efficacy of Spirulina platensis in Egyptian aquaculture

  • 期刊论文

  • 发表日期：

    2026年5月12日

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  • Ahmed Mohamed M. Hegazy,
  • Riad H. Khalil,
  • Mahmoud T. Amer,
  • Hany M. R. Abdel-Latif,
  • Mohamed Fathi

摘要

The sustainable expansion of striped catfish (P. hypophthalmus) aquaculture in Egypt is constrained by environmental stressors, recurrent bacterial infections, and rising antimicrobial resistance. This study offers the first integrated assessment of water quality parameters, pathogen identity and virulence, antimicrobial resistance (AMR) patterns, and the immunoprotective potential of dietary S. platensis under Egyptian farming conditions. Field assessments from naturally infected farms revealed chronic hypoxia (mean DO 3.66 mg L−1) and persistent thermal stress (32.6 °C), both significantly outside recommended ranges, while nitrite levels approached the known toxicity threshold. Two major bacterial pathogens—Aeromonas hydrophila and Streptococcus agalactiae—were isolated with comparable prevalences across liver, kidney, and spleen tissues. Molecular characterization (16S rRNA sequencing; GenBank PX371951 and PX371952) confirmed their identity. Probit challenge assays demonstrated markedly higher virulence for A. hydrophila (LD50 = 1.05 × 105 CFU fish−1) compared with S. agalactiae (LD50 = 1.06 × 106 CFU fish−1). Both species exhibited multidrug resistance, notably universal resistance to penicillin (A. hydrophila) and high resistance to ampicillin, tetracycline, and amikacin (S. agalactiae), underscoring the limitations of empirical antibiotic use. A 4-week feeding trial demonstrated that dietary S. platensis (5 g kg−1) significantly enhanced innate immunity, reduced stress (lower cortisol) and oxidative damage (lower malondialdehyde), and improved antioxidant enzyme activities (SOD, catalase). Spirulina supplementation reduced mortality by 22.6% after A. hydrophila challenge and by 79.2% after S. agalactiae challenge, demonstrating substantial immunomodulatory and protective benefits. Overall, this work highlights critical environmental stressors and AMR challenges in Egyptian catfish farming and identifies Spirulina platensis as a practical, eco-friendly immunostimulant that can reduce disease burden in striped catfish aquaculture. Overall, this work highlights critical environmental stressors and AMR challenges in Egyptian catfish farming and identifies Spirulina platensis as a practical, eco-friendly immunostimulant that can reduce disease burden in striped catfish aquaculture, suggesting promising avenues for improving disease resilience in health management strategies.