CTX-M-1, CTX-M-3, and CTX-M-14 beta-lactamases from Enterobacteriaceae isolated in France

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• CTX-M enzymes are a growing cause of antimicrobial resistance in Enterobacteriaceae.
• Understanding the genetic basis and spread of CTX-M enzymes is crucial for infection control.

Purpose of the Study:

• To characterize CTX-M-producing Enterobacteriaceae isolates from French hospitals.
• To investigate the genetic elements associated with CTX-M gene expression and dissemination.

Main Methods:

• Clinical isolates of Enterobacteriaceae were collected and screened for CTX-M production.
• Molecular techniques were used to identify specific CTX-M variants (CTX-M-1, CTX-M-3, CTX-M-14).
• Plasmid analysis and sequencing were performed to identify associated genetic elements like ISEcp-1.

Main Results:

• Six clinical CTX-M-producing Enterobacteriaceae isolates were detected between 1999-2000.
• Four isolates produced CTX-M-14, a CTX-M-9 mutant, while two produced CTX-M-1 and CTX-M-3.
• The transposable element ISEcp-1 was found upstream of all bla(CTX-M) genes.
• CTX-M-14-encoding plasmids showed similar restriction patterns, and CTX-M-1/3 plasmids were related to previously reported ones.

Conclusions:

• The emergence of CTX-M-14, a CTX-M-9 mutant, was observed in French clinical isolates.
• The ISEcp-1 element appears to play a role in the mobilization and expression of CTX-M genes.
• Plasmid-mediated dissemination of CTX-M genes, including relatedness to older strains, continues to be a concern.