Genomic Analysis Of Multidrug Resistant Pseudomonas Aeruginosa PAG5

Pseudomonas aeruginosa is a common Gram-negative opportunistic pathogen that causes a wide range of infections via the diverse resistance mechanisms.Plasmid contributes to the horizontal transfer of resistance genes.Based on previousely reported,the majority of resistance plasmid belongs to IncP-2 family plasmid in P.aeruginosa.The IncP-2 family plasmid often possesses characteristic properties: 1)narrow host range,horizontal transfer occur only between the same genus;2)single copy number and very large;3)possesses heavy and phage resistance;4)most plasmid comprise streptomycin and sulfonamides resistance.It is obvious that those properties contribute to impove the bacterial adaptive in the diverse environmental conditions and cause the rapid transmission of resistance.Nevertheless,how to form the resistance plasmid and drive the rapid transmission mechanism in the clinical settings remains are not well characterizated to date.P.aeruginosa strain PAG5 was isolated from clinical sample in the early study,whole-genome sequencing was performed by hybrid approach to analyse the reason of the multidrug resistance and the formation of resistant plasmid pPAG5.The resistance genes,genetic background of resistance genes,mobile genetic elements and multidrug resistance regions were analyzed.In addition,the formation of plasmid pPAG5 and the origin of pPAG5 and related plasmids were studiedThe results indicated the genome was 7229900 bpin length with two circular contigs,the large contig is the chromosomal genome(Genebank accession number: CP045002)with length of 6716578 bpand GC content of 66.05% and contains 6586 protein-coding genes.The small contig is the plasmid genome(Genebank accession number: CP045003)with length of513322 bpand GC content of 56.31% and contains 538 protein-coding genes,was designed pPAG5.The plasmid pPAG5 was considered as the IncP-2 family due to possess the replication protein RepA is equal to that of pJB37 and pOZ176.Plasmid pPAG5 belonged to narrow-host and conjugative plasmid via conjugation experiments.The formation of two multidrug resistant regions(MDR-1 and MDR-2)by 12 diverse classes of resistance genes in the plasmid pPAG5,BLASTn search indicated that MDR-1 exhibits highly similar to pSY153-MDR(99.98% identity)and plasmid of P.aeruginosa 14.1819(99.96%identity);MDR-2 displays highly similar to pSY153-MDR(99.98% identity).The presence of insertion sequence IS26 between Tn6023-like and Tn1548-like,IS26 may mediate the homologous recombination between them;the presence of common region of insertion sequence ISCR1 between Tn1548-like and In786,homologous recombination may be mediate by ISCR1.VR1 fragment was flanked by serine recombinase and IS6100,VR1 fragment integrate into pPAG5 genome may due to homologous recombination mediated by serine recombinase and IS6100;VR2 fragment was flanked by ISPa1328 and IS1411,VR2 fragment was acquired through ISPa1328 and IS1411 mediated homologous recombination.Based on the above results,the plasmid pPAG5 plays a critical role in the formation of multidrug resistance.Mobile genetic elements can capture resistance genes and form the multidrug resistance regions by homologous recombination.The unique function genes are captured in order to gain adaptive ability in the bacterial evolution.This study contribute to gain the understanding of the dissemination of antibiotic resistance genes and emergence of multidrug resistant bacteria,as well as further understanding of the molecular evolution mechanism of bacterial adaptation.