Derepressed transfer properties leading to the efficient spread of the plasmid encoding carbapenemase OXA-48

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Carbapenemase-producing Enterobacteriaceae (CPE) pose a significant global health threat.
• The OXA-48 carbapenemase is a notable cause of carbapenem resistance in Enterobacteriaceae.
• The IncL/M-type plasmid pOXA-48a is frequently associated with the spread of OXA-48.

Purpose of the Study:

• To investigate the genetic elements and mechanisms contributing to the dissemination of the pOXA-48a plasmid.
• To understand the role of the Tn1999 transposon in the spread of OXA-48 carbapenemase.

Main Methods:

• Plasmid analysis
• Gene sequencing
• Transfer frequency assays

Main Results:

• The blaOXA-48 gene is located within the Tn1999 composite transposon.
• Tn1999 is inserted into the tir gene, which encodes a transfer inhibition protein.
• Insertion of Tn1999 into the tir gene significantly increased the transfer frequency of the pOXA-48a plasmid.

Conclusions:

• The insertion of Tn1999 into the tir gene is a key factor in the efficient dissemination of the pOXA-48a plasmid.
• This mechanism likely contributes to the successful spread of OXA-48 carbapenemase among Enterobacteriaceae.