A Novel Transposon Tn7709 Harbors Multidrug Resistance Genes in a Pathogenic Aeromonas media Strain QST31

Area of Science:

• Aquatic microbiology
• Antimicrobial resistance research
• Pathogen identification

Background:

• Motile Aeromonas Septicemia (MAS) is a significant disease in aquatic animals.
• Aeromonas species are known pathogens, but specific strains in tadpoles require further investigation.
• Understanding antibiotic resistance in aquatic pathogens is crucial for disease management.

Purpose of the Study:

• To identify the bacterial pathogen responsible for disease in Quasipaa spinosa tadpoles.
• To characterize the antibiotic resistance profile of the isolated bacterium.
• To investigate the genetic basis of antimicrobial resistance in the identified strain.

Main Methods:

• Isolation and identification of the bacterium using biochemical tests and molecular methods.
• Virulence assessment through artificial infection experiments in tadpoles.
• Antimicrobial susceptibility testing using the disk diffusion method.
• Whole genome sequencing to identify antimicrobial resistance genes, integrons, and transposons.

Main Results:

• A highly virulent Aeromonas media strain (QST31) was isolated from diseased tadpoles.
• Strain QST31 exhibited resistance to 28 different antibacterial agents.
• Whole genome sequencing revealed over 12 antimicrobial resistance genes, including a novel Tn7709 transposon.
• The genome contained genes associated with virulence, such as adherence and hemolysis.

Conclusions:

• This is the first report of pathogenic, multidrug-resistant Aeromonas media isolated from diseased tadpoles.
• The identified strain poses a significant challenge for the prevention and control of aquatic animal diseases.
• Further research is needed to understand and combat the spread of antibiotic resistance in aquaculture.