Complete sequence of the IncT-type plasmid pT-OXA-181 carrying the blaOXA-181 carbapenemase gene from Citrobacter...

Area of Science:

• Molecular biology
• Microbiology
• Genetics

Background:

• Carbapenemase-producing Enterobacteriaceae (CPE) pose a significant global health threat.
• OXA-48-like carbapenemases are a clinically relevant group of beta-lactamases.
• Plasmid-mediated resistance mechanisms facilitate the rapid spread of antibiotic resistance genes.

Purpose of the Study:

• To characterize the genetic environment of the blaOXA-181 gene in a Citrobacter freundii isolate.
• To determine the complete sequence and type of the plasmid carrying blaOXA-181.
• To compare the blaOXA-181-carrying plasmid with other previously identified plasmids.

Main Methods:

• Whole-genome sequencing of the Citrobacter freundii isolate.
• Plasmid DNA extraction and sequencing.
• Bioinformatic analysis to determine plasmid structure and identify mobile genetic elements.

Main Results:

• Identification of the blaOXA-181 gene, encoding an OXA-48 variant carbapenemase, in a Citrobacter freundii isolate also producing NDM-1.
• Determination of the complete 84-kb sequence of plasmid pT-OXA-181, an IncT-type plasmid that is mobilizable but not self-conjugative.
• Comparison reveals pT-OXA-181 is distinct from a previously reported 7.6-kb ColE-type plasmid carrying blaOXA-181 in Klebsiella pneumoniae.

Conclusions:

• The blaOXA-181 gene can be located on different plasmid types, highlighting diverse dissemination routes.
• The insertion sequence ISEcp1 may have played a role in the acquisition of the blaOXA-181 gene in both identified plasmids.
• Understanding plasmid diversity is crucial for tracking and controlling the spread of carbapenemase genes.