Abstract
Background: Lateral gene transfer plays a central role in the dissemination of carbapenem resistance in bacterial pathogens associated with nosocomial infections, mainly Enterobacteriaceae and Pseudomonas aeruginosa. Despite their clinical significance, there is little information regarding the mobile genetic elements and mechanism of acquisition and propagation of lateral genes in P. aeruginosa, and they remain largely unknown.Objectives: The present study characterized the genetic context of blaKPC-2 in carbapenem-resistant P. aeruginosa strain BH9.Methods: Pseudomonas aeruginosa BH9 sequencing was performed using the long-read PacBio SMRT platform and the Ion Proton System. De novo assembly was carried out using the SMRT pipeline and Canu, and gene prediction and annotation were performed using Prokka and RAST.Results: Pseudomonas aeruginosa BH9 exhibited a 7.1 Mb circular chromosome. However, the blaKPC-2 gene is located in an additional contig composed by a small plasmid pBH6 from P. aeruginosa strain BH6 and several phage-related genes. Further analysis revealed that the beginning and end of the contig contain identical sequences, supporting a circular plasmid structure. This structure spans 41,087 bp, exhibiting all the Mu-like phage landmarks. In addition, 5-bp direct repeats (GGATG) flanking the pBH6 ends were found, strongly indicating integration of the Mu-like phage into the pBH6 plasmid. Mu phages are commonly found in P. aeruginosa. However, for the first time showing a potential impact in shaping the vehicles of the dissemination of antimicrobial (e.g., plasmid pBH6) resistance genes in the Pseudomonas genus.Conclusion: pBH6 captured the Mu-like Phage BH9, creating a co-integrate pBH6::Phage BH9, and this phage-plasmid complex may represent novel case of a phage-like plasmid.
Highlights
Carbapenem resistance mediated by the production of Klebsiella pneumoniae carbapenemase (KPC) enzymes has been reported worldwide in Enterobacteriaceae and Pseudomonas aeruginosa, and the blaKPC−2 gene has been found to be associated with different transposon families and plasmids (Galetti et al, 2016; Naas et al, 2016)
The blaKPC−2 gene is located in an additional contig composed by a small plasmid pBH6 from P. aeruginosa strain BH6 and several phage-related genes
For the first time showing a potential impact in shaping the vehicles of the dissemination of antimicrobial resistance genes in the Pseudomonas genus
Summary
Carbapenem resistance mediated by the production of Klebsiella pneumoniae carbapenemase (KPC) enzymes has been reported worldwide in Enterobacteriaceae and Pseudomonas aeruginosa, and the blaKPC−2 gene has been found to be associated with different transposon families and plasmids (Galetti et al, 2016; Naas et al, 2016). Transduction is genetic exchange mediated by independently replicating bacterial viruses called bacteriophages, or phages These genetic elements are frequently associated with the dissemination and persistence of virulence genes and pathogenicity islands in primary human pathogens and foodborne pathogens (Marti et al, 2014; Colavecchio et al, 2017a; Pallen and Wren, 2007). Lateral gene transfer plays a central role in the dissemination of carbapenem resistance in bacterial pathogens associated with nosocomial infections, mainly Enterobacteriaceae and Pseudomonas aeruginosa. Despite their clinical significance, there is little information regarding the mobile genetic elements and mechanism of acquisition and propagation of lateral genes in P. aeruginosa, and they remain largely unknown
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