A blaVEB-1 variant, blaVEB-6, associated with repeated elements in a complex genetic structure.

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• The bla(VEB) gene family encodes extended-spectrum beta-lactamases (ESBLs).
• Integrons are genetic elements that facilitate the acquisition of antibiotic resistance genes.
• Proteus mirabilis is a common opportunistic pathogen often associated with healthcare-associated infections.

Purpose of the Study:

• To characterize the genetic context and location of the novel bla(VEB-6) gene.
• To investigate the association of bla(VEB-6) with mobile genetic elements and other resistance genes.
• To understand the evolutionary mechanisms contributing to the spread of antimicrobial resistance.

Main Methods:

• Whole-genome sequencing of Proteus mirabilis isolate.
• Bioinformatic analysis of gene cassettes, integrons, and flanking regions.
• Comparative analysis with known bla(VEB) variants and mobile elements.

Main Results:

• The bla(VEB-6) gene was identified on the Proteus mirabilis chromosome within a truncated gene cassette.
• This cassette was flanked by specific repetitive elements and duplications characteristic of class 1 integrons.
• A linked cassette array (aacA4-aadB-dfrA1-orfC) containing elements of Tn1331 was observed, indicating complex mosaicism.

Conclusions:

• The bla(VEB-6) gene is integrated into the bacterial chromosome via an integron structure.
• The genetic environment of bla(VEB-6) highlights the role of integrons and transposons in assembling multiresistance gene arrays.
• This complex arrangement contributes to the adaptability and dissemination of antimicrobial resistance in Proteus mirabilis.