Identification and characterization of IS1476, an insertion sequence-like element that disrupts VanY function in a...

Area of Science:

• Microbiology
• Molecular Biology
• Antimicrobial Resistance

Background:

• Vancomycin-resistant enterococci (VRE) pose a significant threat to public health.
• The vanY gene encodes a D,D-carboxypeptidase enzyme crucial for peptidoglycan biosynthesis.
• Understanding the genetic mechanisms of vancomycin resistance is vital for developing new therapeutic strategies.

Purpose of the Study:

• To investigate the genetic basis of vancomycin resistance in a clinical isolate of Enterococcus faecium.
• To identify any novel genetic elements associated with the vanY gene in VRE.

Main Methods:

• Polymerase Chain Reaction (PCR) was employed to detect genetic elements within the vanY gene.
• A fluorometric assay using diacetyl-L-Lys-D-Ala-D-Ala substrate was used to measure D,D-carboxypeptidase activity.
• Characterization of identified insertion sequence (IS)-like elements.

Main Results:

• An insertion sequence (IS)-like element, designated IS1476, was identified within the vanY gene of a VanA Enterococcus faecium isolate.
• The presence of IS1476 was associated with decreased activity of the VanY D,D-carboxypeptidase enzyme.
• This represents the first reported instance of an IS-like element within a vancomycin resistance gene.

Conclusions:

• IS1476 is a novel insertion sequence element found in the vanY gene of VRE.
• IS1476 may contribute to vancomycin resistance by reducing the activity of the VanY D,D-carboxypeptidase.
• This discovery provides new insights into the genetic diversity and evolution of antimicrobial resistance mechanisms.