Polluted wetlands contain multidrug-resistance plasmids encoding CTX-M-type extended-spectrum β-lactamases.

Area of Science:

• Environmental microbiology
• Molecular biology
• Genetics

Background:

• Antibiotic resistance plasmids are extensively studied in clinical settings.
• The environmental reservoir of mobile genetic elements and their encoded factors remains underexplored.

Purpose of the Study:

• To investigate antibiotic resistance and virulence factors in plasmids from environmental bacteria.
• To characterize the transferability and genetic content of cefotaxime-resistant Escherichia coli plasmids.

Main Methods:

• Selective isolation of cefotaxime-resistant E. coli from a coastal wetland.
• Conjugation experiments to assess plasmid transfer to recipient strains.
• Whole-genome sequencing of isolated plasmids.

Main Results:

• Three strains of cefotaxime-resistant E. coli were isolated, with plasmids exhibiting high transfer frequencies.
• Plasmids conferred resistance to cephalosporins and at least seven other antibiotic classes.
• Sequenced IncF-type plasmids (F31:A4:B1, F18:B1:C4) carried diverse antibiotic resistance (blaCTX-M-15/blaCTX-M-55) and virulence genes.

Conclusions:

• Environmental selection with cefotaxime enriches for conjugative plasmids carrying multiple resistance and virulence genes.
• Understanding mobile genetic elements in environmental reservoirs is crucial for combating antibiotic resistance spread.