Integron diversity in blavim-2-carrying carbapenem-resistant clinical Pseudomonas aeruginosa isolates.

Abstract

The growing prevalence of metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa in nosocomial pathogen populations has been attributed to their clonal spread, and/or horizontal transfer of MBL determinants in mobile genetic elements, including integrons. To characterize the genetic background of the beta-lactamase VIM-2 encoding gene in the population of carbapenemresistant (Carba-R) P. aeruginosa clinical isolates.The detection of class 1 integrons was performed by PCR. Typing of the class 1 integrons containing the blaVIM gene cassette was performed by the PCR-restriction fragment length polymorphism (RFLP) approach followed by sequencing of variable regions of class 1 integrons. Five types of the blaVIM-2-carrying integrons were identified: ST654-isolates accounting for more than 50% of the Carba-R population harbored In56; ST235-isolates contained In559 (26% Carba-R isolates); ST111-isolates (19% Carba-R isolates) were characterized by carrying In59-like integron; two ST235-isolates harbored In59 and In249 each. Except In56, carrying the only blaVIM-2-gene cassette, all other identified integron types harbored the genes of resistance to trimethoprim and/or aminoglycosides. No new types of integrons were identified in the P. aeruginosa clinical isolates. The observed correlation of the integron type with specific STs indicates a clonal dissemination of significant resistance determinant producers - ST111, ST654 and ST235 epidemic lines. The features of the integron variable regions can be used for the epidemiological characterization of clinical P. aeruginosa isolates.