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Published on: December 23, 2022
Isolation, identification, and genomic features of Proteus mirabilis from diseased Asian arowana Scleropages formosus
Han Yang1,2, Siyi Wen2, Zhuoran Han1,2
1Key Laboratory of Smart Breeding (Co-construction by Ministry and Province), Tianjin Agricultural University, Tianjin 300384, PR China.
Abstract:
Proteus mirabilis is a Gram-negative opportunistic pathogen increasingly reported in aquatic animals; however, its pathogenic potential and genomic features in ornamental fish remain unclear. This study isolated 3 strains (WSY-112, WSY-113, and WSY-114) from diseased Asian arowana Scleropages formosus displaying hemorrhagic and ulcerative lesions. All 3 isolates were identified as P. mirabilis through physiological and biochemical characterization as well as 16S rRNA and gyrB sequencing. Strain WSY-114 was selected for further analyses, including whole-genome sequencing, antimicrobial susceptibility testing, and experimental infection. Genomic annotation identified multiple virulence-related genes for flagellar assembly, adhesion, toxin production, iron acquisition, and type III/IV/VI secretion systems. Experimental infection in zebrafish Danio rerio showed dose-dependent mortality (LD50 = 6.6 × 104 CFU g-1) and clinical signs mirroring natural infections in the arowana. The strain exhibited resistance to multiple tested antibiotics, including tetracyclines (tetracycline, minocycline, and doxycycline), macrolides (erythromycin and azithromycin), and ampicillin, consistent with antibiotic-resistance genes detected in its genome. These results indicate that P. mirabilis exhibits pathogenic potential under experimental conditions and may represent a potential risk factor in ornamental fish.
Insights
Proteus mirabilis is an opportunistic pathogen found in aquatic animals. This study confirms its pathogenic potential in ornamental fish, identifying virulence factors and antibiotic resistance in a diseased Asian arowana strain.
Area of Science:
- Aquatic microbiology
- Fish pathology
- Bacterial genomics
Background:
- Proteus mirabilis is an opportunistic pathogen increasingly found in aquatic environments.
- Its role and genomic characteristics in ornamental fish diseases are not well understood.
Purpose of the Study:
- To investigate the pathogenic potential and genomic features of Proteus mirabilis isolated from diseased ornamental fish.
- To characterize the virulence factors and antimicrobial resistance of the isolated strains.
Main Methods:
- Isolation and identification of Proteus mirabilis from diseased Asian arowana (Scleropages formosus).
- Whole-genome sequencing, phylogenetic analysis, and virulence gene identification.
- Antimicrobial susceptibility testing and experimental infection in zebrafish (Danio rerio).
Main Results:
- Three Proteus mirabilis strains were isolated and identified.
- Genomic analysis revealed genes associated with virulence, including flagellar assembly, adhesion, and secretion systems.
- Experimental infection demonstrated dose-dependent pathogenicity in zebrafish, with mortality and clinical signs similar to natural infections.
- The strain exhibited resistance to multiple antibiotics, including tetracyclines, macrolides, and ampicillin, correlating with detected resistance genes.
Conclusions:
- Proteus mirabilis possesses pathogenic potential in ornamental fish, posing a risk to aquaculture.
- The identified virulence factors and antibiotic resistance highlight the need for monitoring and control strategies.
