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A glimpse into evolution and dissemination of multidrug-resistant Acinetobacter baumannii isolates in East Asia: a comparative genomics study.

Feng Y, Ruan Z, Shu J, Chen CL, Chiu CH - Sci Rep (2016)

Bottom Line: Here we sequenced the genomes of 13 multidrug-resistant (MDR) A. baumannii strains from Taiwan, and compared them with that of A. baumannii from other East Asian countries.Frequent structural variation was detected even between the closely related strains in antimicrobial resistance elements such as AbaRI, class I integron, indicating strong selection pressure brought by antimicrobial use.In conclusion, wide clonal dissemination and frequent genomic variation simultaneously characterize the clinical MDR A. baumannii in East Asia.

View Article: PubMed Central - PubMed

Affiliation: Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.

ABSTRACT
Clonal dissemination is characteristic of the important nosocomial pathogen Acinetobacter baumannii, as revealed by previous multi-locus sequence typing (MLST) studies. However, the disseminated phyletic unit is actually MLST sequence type instead of real bacterial clone. Here we sequenced the genomes of 13 multidrug-resistant (MDR) A. baumannii strains from Taiwan, and compared them with that of A. baumannii from other East Asian countries. Core-genome phylogenetic tree divided the analyzed strains into three major clades. Among them, one ST455 clade was a hybrid between the ST208 clade and the other ST455 clade. Several strains showed nearly identical genome sequence, but their isolation sources differed by over 2,500 km and 10 years apart, suggesting a wide dissemination of the phyletic units, which were much smaller than the sequence type. Frequent structural variation was detected even between the closely related strains in antimicrobial resistance elements such as AbaRI, class I integron, indicating strong selection pressure brought by antimicrobial use. In conclusion, wide clonal dissemination and frequent genomic variation simultaneously characterize the clinical MDR A. baumannii in East Asia.

No MeSH data available.


Histogram of pairwise SNP distances.100 SNPs is used as the cut-off value for defining subclades.
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f4: Histogram of pairwise SNP distances.100 SNPs is used as the cut-off value for defining subclades.

Mentions: A deeper look inside each of the phylogenetic clades was taken by counting the number of pairwise SNPs within clades (Fig. 4). The first peak centered at the distance of <50 SNPs and finished prior to 100 SNPs. By taking the 100-SNP distance as the cut-off value, four subclades were identified (Fig. 2). Although being genetically close to each other, the strains within the same subclades showed highly diverse isolation sites and time. Taking SubClade 1 and SubClade 2 as an example, the strains came from different provinces of China, which were over 3,000 km apart at most (Figs 1B and 2); the earliest strain was isolated in the year 2005, and the most recent strain was in 2014.


A glimpse into evolution and dissemination of multidrug-resistant Acinetobacter baumannii isolates in East Asia: a comparative genomics study.

Feng Y, Ruan Z, Shu J, Chen CL, Chiu CH - Sci Rep (2016)

Histogram of pairwise SNP distances.100 SNPs is used as the cut-off value for defining subclades.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4829828&req=5

f4: Histogram of pairwise SNP distances.100 SNPs is used as the cut-off value for defining subclades.
Mentions: A deeper look inside each of the phylogenetic clades was taken by counting the number of pairwise SNPs within clades (Fig. 4). The first peak centered at the distance of <50 SNPs and finished prior to 100 SNPs. By taking the 100-SNP distance as the cut-off value, four subclades were identified (Fig. 2). Although being genetically close to each other, the strains within the same subclades showed highly diverse isolation sites and time. Taking SubClade 1 and SubClade 2 as an example, the strains came from different provinces of China, which were over 3,000 km apart at most (Figs 1B and 2); the earliest strain was isolated in the year 2005, and the most recent strain was in 2014.

Bottom Line: Here we sequenced the genomes of 13 multidrug-resistant (MDR) A. baumannii strains from Taiwan, and compared them with that of A. baumannii from other East Asian countries.Frequent structural variation was detected even between the closely related strains in antimicrobial resistance elements such as AbaRI, class I integron, indicating strong selection pressure brought by antimicrobial use.In conclusion, wide clonal dissemination and frequent genomic variation simultaneously characterize the clinical MDR A. baumannii in East Asia.

View Article: PubMed Central - PubMed

Affiliation: Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.

ABSTRACT
Clonal dissemination is characteristic of the important nosocomial pathogen Acinetobacter baumannii, as revealed by previous multi-locus sequence typing (MLST) studies. However, the disseminated phyletic unit is actually MLST sequence type instead of real bacterial clone. Here we sequenced the genomes of 13 multidrug-resistant (MDR) A. baumannii strains from Taiwan, and compared them with that of A. baumannii from other East Asian countries. Core-genome phylogenetic tree divided the analyzed strains into three major clades. Among them, one ST455 clade was a hybrid between the ST208 clade and the other ST455 clade. Several strains showed nearly identical genome sequence, but their isolation sources differed by over 2,500 km and 10 years apart, suggesting a wide dissemination of the phyletic units, which were much smaller than the sequence type. Frequent structural variation was detected even between the closely related strains in antimicrobial resistance elements such as AbaRI, class I integron, indicating strong selection pressure brought by antimicrobial use. In conclusion, wide clonal dissemination and frequent genomic variation simultaneously characterize the clinical MDR A. baumannii in East Asia.

No MeSH data available.