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Carbapenem and amikacin resistance on a large conjugative Acinetobacter baumannii plasmid.

Nigro SJ, Holt KE, Pickard D, Hall RM - J. Antimicrob. Chemother. (2014)

View Article: PubMed Central - PubMed

Affiliation: School of Molecular Bioscience, The University of Sydney, Sydney, New South Wales, Australia steven.nigro@sydney.edu.au.

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Sir, Worldwide, most multiply antibiotic-resistant (MAR), and particularly carbapenem-resistant, Acinetobacter baumannii causing infections belong to global clone 1 (GC1) or global clone 2 (GC2)... Using PCR as described previously, D46 was shown to contain the strA-strB, sul2 and tetA(B) genes, responsible for streptomycin, sulfamethoxazole and tetracycline resistance, respectively... These genes were in the same configuration as in AbGRI1-2 (Tn6167), but D46 does not have an island in comM... To determine whether D46 harboured Tn2006 together with TnaphA6 on a plasmid related to pAb-G7-2 and pD72-2, contigs that matched them were retrieved from the draft genome... It was described as a plasmid related to pACICU2, harbouring ISAba1 upstream of aphA6 and having a copy of blaOXA-23 flanked by two copies of ISAba125 that is in the same position as ISAba125 in pACICU2... The backbones of the repAci6 plasmids, pAb-G7-2, pD72-2, pD46-3, pABUH1 and pACICU2, are all very closely related, but they can be separated into two lineages based on the position of TnaphA6 (Figure 1)... Representatives of the two lineages, pD46-3 and pABUH1, have each acquired the blaOXA-23 gene on separate occasions and a sixth repAci6 plasmid, pA85-3, has also gained blaOXA-23 within AbaR4... Hence, surveillance of this group of A. baumannii plasmids will be vital in curtailing the spread of carbapenem resistance in A. baumannii... This study was supported by grants from the School of Molecular Bioscience and the Wellcome Trust Sanger Institute... N. was supported by an Australian Postgraduate Award... H. was supported by NHMRC fellowship 628930... None to declare.

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Comparison of repAci6 plasmids pD72-2, pD46-3 (a), pABUH1 and pAb-G7-2 (b). The plasmid backbones, linearized and opened at repA, are represented by horizontal lines. The extent of ORFs and genes are shown as arrows beneath the lines, with names given where a function is known. The transfer region is indicated above each line, the tra genes are indicated with capital letters and trbC is shown as c. The three repeat regions are indicated by the numbered boxes. The structures of TnaphA6, Tn2006 and Tn2008-like are shown above or below the backbone, with IS represented as open boxes containing an arrow showing their orientation.
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DKU486F1: Comparison of repAci6 plasmids pD72-2, pD46-3 (a), pABUH1 and pAb-G7-2 (b). The plasmid backbones, linearized and opened at repA, are represented by horizontal lines. The extent of ORFs and genes are shown as arrows beneath the lines, with names given where a function is known. The transfer region is indicated above each line, the tra genes are indicated with capital letters and trbC is shown as c. The three repeat regions are indicated by the numbered boxes. The structures of TnaphA6, Tn2006 and Tn2008-like are shown above or below the backbone, with IS represented as open boxes containing an arrow showing their orientation.

Mentions: To determine whether D46 harboured Tn2006 together with TnaphA6 on a plasmid related to pAb-G7-25 and pD72-2,7 contigs that matched them were retrieved from the draft genome. Seven contigs were recovered and assembled using PCR.5,7 The amplicons were sequenced, finalizing the assembly. Plasmid pD46-3 has a 67 027 bp backbone sharing 99.99% identity (five single-base changes) with that of pD72-2 (Figure 1a). pD46-3 also harboured TnaphA6 in the same position as pD72-2 (Figure 1a). One end of two backbone contigs had inversely oriented fragments of ISAba1 and they were linked with blaOXA-23 in Tn2006 using PCR (Figure 1a). The complete 74 916 bp sequence of pD46-3 was deposited in GenBank under accession number KM977710. As the backbone of pD46-3 was almost identical to that of pD72-2 and pAb-G7-2, pD46-3 also contained the complete set of transfer genes (Figure 1). This is the first report of a completely sequenced A. baumannii plasmid that has been demonstrated to simultaneously transfer resistance to carbapenems and aminoglycosides.Figure 1.


Carbapenem and amikacin resistance on a large conjugative Acinetobacter baumannii plasmid.

Nigro SJ, Holt KE, Pickard D, Hall RM - J. Antimicrob. Chemother. (2014)

Comparison of repAci6 plasmids pD72-2, pD46-3 (a), pABUH1 and pAb-G7-2 (b). The plasmid backbones, linearized and opened at repA, are represented by horizontal lines. The extent of ORFs and genes are shown as arrows beneath the lines, with names given where a function is known. The transfer region is indicated above each line, the tra genes are indicated with capital letters and trbC is shown as c. The three repeat regions are indicated by the numbered boxes. The structures of TnaphA6, Tn2006 and Tn2008-like are shown above or below the backbone, with IS represented as open boxes containing an arrow showing their orientation.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4356202&req=5

DKU486F1: Comparison of repAci6 plasmids pD72-2, pD46-3 (a), pABUH1 and pAb-G7-2 (b). The plasmid backbones, linearized and opened at repA, are represented by horizontal lines. The extent of ORFs and genes are shown as arrows beneath the lines, with names given where a function is known. The transfer region is indicated above each line, the tra genes are indicated with capital letters and trbC is shown as c. The three repeat regions are indicated by the numbered boxes. The structures of TnaphA6, Tn2006 and Tn2008-like are shown above or below the backbone, with IS represented as open boxes containing an arrow showing their orientation.
Mentions: To determine whether D46 harboured Tn2006 together with TnaphA6 on a plasmid related to pAb-G7-25 and pD72-2,7 contigs that matched them were retrieved from the draft genome. Seven contigs were recovered and assembled using PCR.5,7 The amplicons were sequenced, finalizing the assembly. Plasmid pD46-3 has a 67 027 bp backbone sharing 99.99% identity (five single-base changes) with that of pD72-2 (Figure 1a). pD46-3 also harboured TnaphA6 in the same position as pD72-2 (Figure 1a). One end of two backbone contigs had inversely oriented fragments of ISAba1 and they were linked with blaOXA-23 in Tn2006 using PCR (Figure 1a). The complete 74 916 bp sequence of pD46-3 was deposited in GenBank under accession number KM977710. As the backbone of pD46-3 was almost identical to that of pD72-2 and pAb-G7-2, pD46-3 also contained the complete set of transfer genes (Figure 1). This is the first report of a completely sequenced A. baumannii plasmid that has been demonstrated to simultaneously transfer resistance to carbapenems and aminoglycosides.Figure 1.

View Article: PubMed Central - PubMed

Affiliation: School of Molecular Bioscience, The University of Sydney, Sydney, New South Wales, Australia steven.nigro@sydney.edu.au.

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

Sir, Worldwide, most multiply antibiotic-resistant (MAR), and particularly carbapenem-resistant, Acinetobacter baumannii causing infections belong to global clone 1 (GC1) or global clone 2 (GC2)... Using PCR as described previously, D46 was shown to contain the strA-strB, sul2 and tetA(B) genes, responsible for streptomycin, sulfamethoxazole and tetracycline resistance, respectively... These genes were in the same configuration as in AbGRI1-2 (Tn6167), but D46 does not have an island in comM... To determine whether D46 harboured Tn2006 together with TnaphA6 on a plasmid related to pAb-G7-2 and pD72-2, contigs that matched them were retrieved from the draft genome... It was described as a plasmid related to pACICU2, harbouring ISAba1 upstream of aphA6 and having a copy of blaOXA-23 flanked by two copies of ISAba125 that is in the same position as ISAba125 in pACICU2... The backbones of the repAci6 plasmids, pAb-G7-2, pD72-2, pD46-3, pABUH1 and pACICU2, are all very closely related, but they can be separated into two lineages based on the position of TnaphA6 (Figure 1)... Representatives of the two lineages, pD46-3 and pABUH1, have each acquired the blaOXA-23 gene on separate occasions and a sixth repAci6 plasmid, pA85-3, has also gained blaOXA-23 within AbaR4... Hence, surveillance of this group of A. baumannii plasmids will be vital in curtailing the spread of carbapenem resistance in A. baumannii... This study was supported by grants from the School of Molecular Bioscience and the Wellcome Trust Sanger Institute... N. was supported by an Australian Postgraduate Award... H. was supported by NHMRC fellowship 628930... None to declare.

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Related in: MedlinePlus