Morganella morganii Emerges as Significant Pathogen in Aquaculture

A new report from researchers at Shanghai Fisheries Research Institute sheds light on the effects of Morganella morganii on largemouth bass (Micropterus salmoides). The study found that M. morganii can cause significant mortality and severe pathological changes in infected livers. Histopathological analysis revealed severe granulomatous inflammation and melanomacrophage centers in infected livers. The researchers identified 5799 differentially expressed genes, with significant enrichment in lipid metabolism pathways and immune responses.

Key Takeaways:

• M. morganii has emerged as a significant pathogen in aquaculture, causing over 76% mortality in challenge tests with characteristic hemorrhaging, ascites, and hepatic lesions.
• Histopathological analysis revealed severe granulomatous inflammation and melanomacrophage centers in infected livers.
• Transcriptomic profiling identified 5799 differentially expressed genes, with significant enrichment in lipid metabolism pathways and immune responses.
• Immune regulators (il10, irak4, myd88) were upregulated, while drug metabolism enzymes (cytochrome P450) were suppressed.
• Antibiotic susceptibility testing indicated clinical potential for enrofloxacin and ciprofloxacin treatment, though resistance to azithromycin was observed.
• The researchers identified potential treatment options for M. morganii infection, including enrofloxacin and ciprofloxacin.
• The study highlights the significant threat M. morganii poses to bass aquaculture through metabolic disruption and immune function.

Statistics:

• 76% mortality rate in challenge tests with characteristic hemorrhaging, ascites, and hepatic lesions.
• 5799 differentially expressed genes identified through transcriptomic profiling.
• 105497 - The DOI for the published research in Developmental and Comparative Immunology.
• The study discusses the use of enrofloxacin and ciprofloxacin treatment options, which showed clinical potential.

Sources:

• Pathological insights and molecular responses to Morganella morganii infection in largemouth bass (Micropterus salmoides). Developmental and Comparative Immunology, 2025;172:105497.
• Shanghai Fisheries Research Institute, Shanghai Fisheries Technical Extension Station, Shanghai, 200433, People's Republic of China.
• Elsevier Sci Ltd, 125 London Wall, London, England.