A blaVIM-2 plasmid disseminating in extensively drug-resistant clinical Pseudomonas aeruginosa and Serratia marcescens isolates

VILACOBA E, QUIROGA C, PISTORIO M, FAMIGLIETTI A, RODRÍGUEZ H, KOVENSKY J, DÉRASPE M, RAYMOND F, ROY PH, CENTRÓN D. ; DANIELA CENTRON.

ANTIMICROBIAL AGENTS AND CHEMOTHERAPY

AMER SOC MICROBIOLOGY

Lugar: Washington; Año: 2014

0066-4804

Infections caused by carbapenem-resistant Enterobacteriaceae isolates are an issue of major global concern (1). Genes coding for metallo-β-lactamases (MβLs) enzymes identified in clinical isolates are associated with mobile elements and subject to Horizontal Genetic Transfer (HGT) events (2-6). Despite the abundance and worldwide spread of VIM-2, only plasmids pNOR-2000 from P. aeruginosa COL-1 from France (7-8), and pLD209 from P. putida LD209 from Argentina (9) have been completely sequenced. Here, we report the characterization of plasmid pDCPR1 harboring a blaVIM-2 gene cassette in a Tn402-type class 1 integron, which was isolated from two extensively drug-resistant strains: S. marcescens 68313 (Sanatorio Sagrado Corazón, Argentina, 2012) and P. aeruginosa 802 (burn patient at the Hospital Municipal de Quemados, Argentina, 2005). Isolates were identified at the species level using VITEK 2 Compact (BioMérieux). Antimicrobial susceptibility was determined by the disk diffusion method performed in agar as recommended by the CLSI (10). DNAs from P. aeruginosa 802 and S. marcescens 68313 were isolated using the Master Pure DNA purification kit (Epicentre, Madison, WI, USA). A library was prepared from 500 ng of total DNA. Sequencing was performed using an Illumina MiSeq and assembled using Ray (11). The complete sequence of plasmid pDCPR1 was submitted to GenBank under accession number KJ577613. pDCPR1 was 18,182 bp long with an average G+C content of 58,36%. When we analyzed the plasmid sequence as a whole, we observed that pDCPR1 is derived from a deletion of pLD209 (38,403 bp)(9). pDCPR1 shows complete synteny with part of pLD209, including the replicase (repA), the partitioning system (trfB, parA and parB), the Tn402-like class 1 integron harboring a blaVIM-2 gene cassette and several hypothetical proteins. The genes involved in conjugal transfer and virulence from pLD209 (20,221 bp) are deleted in pDCPR1 (Figure 1). P. putida LD209 was isolated in Argentina in 2009 and P. aeruginosa 802 in Argentina in 2005. Therefore, the presumptive deletion of pLD209 which gave rise to pDCPR1 occurred before 2005. Since then, it is likely that both plasmids, pLD209 and pDCPR1 are circulating in Argentinean samples. Plasmid pDCPR1 was found in two different genera (Pseudomonas and Serratia) 7 years apart and no SNPs nor indels were found. This indicates that this plasmid was not only able to successfully replicate in different organisms, but was capable of surviving in nosocomial environments while maintaining its structure. These features suggest that the bacteria have found an efficient genetic platform for spreading carbapenem resistance among clinical species. This work not only characterizes a plasmid circulating in P. aeruginosa and S. marcescens, but also it is the first report of a blaVIM-2 gene cassette in S. marcescens in Argentina. The acquisition of plasmid pDCPR1 by S. marcescens reinforces the global concern about the dissemination of broad-host-range plasmids involved in the evolution of pandrug resistance in almost all human pathogenic species in strongly selective environments.