Dissemination of blaOXA-23 in Acinetobacter spp. in China: Main Roles of Conjugative Plasmid pAZJ221 and Transposon Tn2009
Dissemination of blaOXA-23 in Acinetobacter spp. in China: Main Roles of Conjugative Plasmid pAZJ221 and Transposon Tn2009
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blaOXA-23 在不动杆菌属中的传播。
DOI：
10.1128/aac.04574-14
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发表时间：
2015-04-01
影响因子：
4.9
通讯作者：
Yu, Yun-Song
中科院分区：
文献类型：
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作者：
Liu, Li-Lin;Ji, Shu-Juan;Yu, Yun-Song
OXA-23碳青霉烯酶的产生是不动杆菌属中碳青霉烯类耐药性增加的最常见原因。本研究旨在揭示bla（OXA-23）在不动杆菌属中传播的遗传基础。在中国本研究共从18个省的28家医院选择了63株碳青霉烯类耐药产OXA-23不动杆菌属菌株，代表不同背景。根据S1核酸酶脉冲场凝胶电泳和Southern印迹杂交，通常检测到两种携带bla（OXA-23）的质粒。一约在23株鲍曼不动杆菌和3株医院感染的不动杆菌中发现了pAZJ 221质粒，命名为pAZJ 221。50-kb质粒仅由另外两株A.鲍曼不动杆菌分离株。这些分离株中有三个在染色体上有额外的bla（OXA-23）拷贝。两个质粒的转化均成功，但只有pAZJ 221是接合的。质粒pAZJ 221完全测序，发现除bla（OXA-23）外不携带先前已知的抗性基因。其余35株的bla（OXA-23）基因为染色体携带。bla（OXA-23）遗传环境与57株分离株的Tn 2009、5株分离株的Tn 2008和1株分离株的Tn 2006相关。碳青霉烯类抗生素对这些分离株的MIC值与bla（OXA-23）的基因组位置或拷贝数无显著相关性。总之，这些观察结果表明质粒pAZJ 221和Tn 2009有效地促进了bla（OXA-23）在不动杆菌属中的广泛传播。水平基因转移在bla（OXA-23）基因传播中可能起重要作用。
Production of the OXA-23 carbapenemase is the most common reason for the increasing carbapenem resistance in Acinetobacter spp. This study was conducted to reveal the genetic basis of bla(OXA-23) dissemination in Acinetobacter spp. in China. A total of 63 carbapenem-resistant OXA-23-producing Acinetobacter sp. isolates, representing different backgrounds, were selected from 28 hospitals in 18 provinces for this study. Generally, two patterns of plasmids carrying bla(OXA-23) were detected according to S1-nuclease pulsed-field gel electrophoresis and Southern blot hybridization. A ca. 78-kb plasmid, designated pAZJ221, was found in 23 Acinetobacter baumannii and three Acinetobacter nosocomialis isolates, while a novel ca. 50-kb plasmid was carried by only two other A. baumannii isolates. Three of these isolates had an additional copy of bla(OXA-23) on the chromosome. Transformation of the two plasmids succeeded, but only pAZJ221 was conjugative. Plasmid pAZJ221 was sequenced completely and found to carry no previously known resistance genes except bla(OXA-23). The bla(OXA-23) gene of the remaining 35 isolates was chromosome borne. The bla(OXA-23) genetic environments were correlated with Tn2009 in 57 isolates, Tn2008 in 5 isolates, and Tn2006 in 1 isolate. The MIC values for the carbapenems with these isolates were not significantly associated with the genomic locations or the copy numbers of bla(OXA-23). Overall, these observations suggest that the plasmid pAZJ221 and Tn2009 have effectively contributed to the wide dissemination of bla(OXA-23) in Acinetobacter spp. in China and that horizontal gene transfer may play an important role in dissemination of the bla(OXA-23) gene.