Characterization of a new genetic environment associated with GES-6 carbapenemase from a Pseudomonas aeruginosa isolate belonging to the high-risk clone ST235

Sir, Pseudomonas aeruginosa is an opportunistic pathogen commonly associated with nosocomial infections.1 The spread of P. aeruginosa strains resistant to carbapenems constitutes an emerging threat worldwide.1 The GES family of enzymes has been identified in several Gram-negative bacteria, such as P. aeruginosa, Klebsiella pneumoniae and Escherichia coli, being responsible for an extended resistance spectrum to several β-lactams.2,3 To date, according to the Lahey Clinic web site (http://www.lahey.org/Studies/), 24 variants of GES have been identified with some presenting carbapenemase activity, which is a matter of great concern. Few GES variants have been identified in Portugal, all of them found in Enterobacteriaceae.3 In Portugal, carbapenemases associated with P. aeruginosa include VIM-2 (the most frequent) and also IMP-5.4 Here, we report the first known worldwide description of the blaGES-6 gene in P. aeruginosa strains associated with a new genetic environment and also the first description of GES-producing P. aeruginosa in Portugal. Schematic representation of the genetic environment of the P. aeruginosa CB1 integron (GenBank accession no. KM210290). The arrows indicate the translation orientation of the coding genes. The 59 base elements are indicated by black circles. In summary, we present the first known worldwide report of the blaGES-6 carbapenemase gene in P. aeruginosa belonging to the high-risk ST235 clone and inserted in a new class I integron that is chromosomally located. Moreover, this is also the first known report of a GES-producing P. aeruginosa in Portugal. This study highlights the risk of further dissemination of the XDR ST235 P. aeruginosa clone and of genetic backgrounds containing class A carbapenemase genes in our country, which deserves future monitoring. This work was funded by FEDER funds through the Operational Programme for Competitiveness Factors – COMPETE and by National Funds through FCT – Foundation for Science and Technology under the project Pest-C/EQB/LA0006/2013. C. S. and F. G. were supported by post-doctoral grants from Fundação para a Ciência e a Tecnologia (SFRH/BPD/70548/2010 and SFRH/BPD/95556/2013, respectively). None to declare.