[Integron diversity in bla_vim-2-carrying carbapenem-resistant clinical Pseudomonas aeruginosa isolates.]

Area of Science:

• Microbiology
• Genetics
• Epidemiology

Background:

• Metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa are a growing concern in nosocomial infections.
• Their spread is linked to clonal dissemination and horizontal gene transfer of resistance determinants via mobile genetic elements like integrons.
• Understanding the genetic context of MBL genes is crucial for controlling their spread.

Purpose of the Study:

• To characterize the genetic background of the VIM-2 beta-lactamase gene in carbapenem-resistant (Carba-R) P. aeruginosa clinical isolates.
• To identify and type the integrons carrying the blaVIM-2 gene cassette.
• To correlate integron types with specific P. aeruginosa sequence types (STs).

Main Methods:

• Polymerase chain reaction (PCR) was used to detect class 1 integrons.
• PCR-restriction fragment length polymorphism (RFLP) and sequencing were employed to type integrons carrying the blaVIM gene cassette.
• Variable regions of class 1 integrons were sequenced.

Main Results:

• Five types of blaVIM-2-carrying integrons were identified.
• Specific integron types were associated with distinct P. aeruginosa sequence types: In56 with ST654 (over 50% of isolates), In559 with ST235 (26%), and In59-like with ST111 (19%).
• All identified integrons, except In56, also carried genes conferring resistance to trimethoprim and/or aminoglycosides.

Conclusions:

• The study identified a correlation between specific integron types and epidemic P. aeruginosa STs (ST111, ST654, ST235).
• This indicates clonal dissemination of key resistance determinants.
• The characterized integron variable regions can serve as valuable tools for the epidemiological surveillance of clinical P. aeruginosa isolates.