School of Molecular Bioscience, University of Sydney, NSW 2006, Australia.
J Antimicrob Chemother. 2011 Nov;66(11):2484-91. doi: 10.1093/jac/dkr356. Epub 2011 Aug 26.
To explore the diversity of genomic resistance islands in multiply antibiotic-resistant Acinetobacter baumannii isolates in global clone 1 (GC1) from Australian hospitals.
PCR was used to characterize isolates, detect antibiotic resistance genes and insertion sequences and screen for genomic resistance islands. Structures of genomic islands were determined by PCR mapping and sequencing. Multilocus sequence typing was performed using the Oxford scheme.
Eleven isolates that belong to GC1 were found among 90 A. baumannii isolated between 2001 and 2010 at Australian hospitals, and 5 were carbapenem resistant. Ten isolates had the features characteristic of AbaR3 and related islands, but one carbapenem-resistant isolate did not. Instead, D36 carried the bla(OXA-23) gene in transposon Tn2006, with Tn2006 in AbaR4, and AbaR4 in the chromosomal comM gene, replacing the AbaR3-type island usually associated with multiply antibiotic-resistant GC1 isolates. D36 was resistant to gentamicin, kanamycin and tobramycin due to the aadB gene cassette in the context found in plasmid pRAY and to sulfamethoxazole due to the sul2 gene. D36 was of a rare sequence type (ST), ST247. Bioinformatic analysis identified five potential transposition genes in the AbaR backbone transposons.
Substantial diversity was observed among the GC1 isolates. This is the first report of AbaR4 replacing the AbaR3-type island seen in most GC1 isolates, and D36 represents a distinct new GC1 lineage. The AbaRs are members of a large, previously undocumented family of transposons that target comM.
探索澳大利亚医院全球克隆 1 (GC1) 多重耐药鲍曼不动杆菌分离株中基因组耐药岛的多样性。
采用 PCR 方法对分离株进行鉴定，检测抗生素耐药基因、插入序列和筛选基因组耐药岛。通过 PCR 图谱和测序确定基因组岛的结构。采用牛津方案进行多位点序列分型。
在 2001 年至 2010 年间澳大利亚医院分离的 90 株鲍曼不动杆菌中发现了 11 株属于 GC1 的分离株，其中 5 株为碳青霉烯类耐药。10 株具有 AbaR3 及其相关岛的特征，但有一株碳青霉烯类耐药分离株没有。相反，D36 携带转座子 Tn2006 中的 bla(OXA-23)基因，Tn2006 位于 AbaR4 中，AbaR4 位于染色体 comM 基因中，取代了通常与多重抗生素耐药 GC1 分离株相关的 AbaR3 型岛。由于在质粒 pRAY 中发现的 aadB 基因盒，D36 对庆大霉素、卡那霉素和妥布霉素具有耐药性，由于 sul2 基因，D36 对磺胺甲恶唑具有耐药性。D36 的序列类型（ST）为 ST247，属于罕见类型。生物信息学分析在 AbaR 骨架转座子中发现了五个潜在的转位基因。
GC1 分离株之间观察到明显的多样性。这是首次报道 AbaR4 取代了大多数 GC1 分离株中看到的 AbaR3 型岛，D36 代表了一个独特的新 GC1 谱系。AbaRs 是一个以前未被记录的大型转座子家族的成员，该家族的靶标是 comM。
