Emergence of plasmid-mediated oxazolidinone resistance gene poxtA from CC17 Enterococcus faecium of pig origin
Emergence of plasmid-mediated oxazolidinone resistance gene poxtA from CC17 Enterococcus faecium of pig origin
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猪源CC17屎肠球菌质粒介导的恶唑烷酮抗性基因poxtA的出现
DOI：
10.1093/jac/dkz250
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发表时间：
2019-09-01
影响因子：
5.2
通讯作者：
Wang, Liping
中科院分区：
文献类型：
--
作者：
Huang, Jinhu;Wang, Mengli;Wang, Liping
目的：研究猪源CC17粪肠球菌广宿主Inc18载体上的恶唑烷酮耐药基因poxtA。对携带poxtA的菌株进行药敏试验、接合试验、S1-PFGE和杂交鉴定。结果：2株CC17粪便埃希菌均为PoxtA阳性。S1-PFGE和杂交结果表明，在WZ27-2和接合子中均含有约62kb的poxtA，而在QF25-1和接合子中发现了大小不一的poxtA。携带poxtA的两个质粒pc25-1和pC27-2属于INC18家族的广寄主质粒，分别携带dfrG、aad、Delta sat4、aph(3‘)-III、erm(B)、tet(M)、tet(L)和fexB。质粒pC27-2与pC25-1基本相同，只是稍有不同。计算的转移频率分别为0.87×10(-8)和1.03×10(-7)。4个相邻的IS1216E形成3个IS1216E易位单位的不稳定性分析表明，形成了一系列镶嵌的环状中间体。结论：在中国不同养殖场的粪肠球菌中发现了由质粒介导的恶唑烷酮抗性基因poxtA。对poxtA遗传背景的比较表明，IS1216E元件在poxtA的传播中起着重要作用。PoxtA与其他抗菌素和重金属抗性基因在INC18家族广泛寄主范围的质粒上的共存可能导致poxtA的共同选择，有助于其持久存在并加速其传播。
Objectives: To characterize the oxazolidinone resistance gene poxtA on broad-host-range Inc18 plasmids from CC17 Enterococcus faecium of pig origin.Methods: Oxazolidinone-resistant E. faecium isolates were screened for the presence of poxtA. The poxtA-carrying isolates were characterized by antimicrobial susceptibility testing, conjugation, S1-PFGE and hybridization. The poxtA-carrying plasmids were completely sequenced and their instability was verified.Results: Two individual CC17 E. faecium strains were positive for poxtA. S1-PFGE and hybridization revealed the presence of a poxtA-carrying plasmid of similar to 62 kb in both WZ27-2 and the transconjugant, while poxtA-carrying plasmids of different sizes were observed in QF25-1 and the transconjugant. The two poxtA-carrying plasmids, pC25-1 and pC27-2, belonged to the broad-host-range plasmids of the Inc18 family and carried dfrG, aadE, Delta sat4, aph(3')-III, erm(B), tet(M), tet(L) and fexB. Plasmid pC27-2 was virtually identical to pC25-1, with minor differences. The calculated transfer frequency was similar to 0.87 x 10(-8) and similar to 1.03 x 10(-7) per recipient to plasmids pC25-1 and pC27-2, respectively. Instability assays of the region with four adjacent IS1216Es, which forms three IS1216E translocatable units, revealed the formation of a series of mosaic circular intermediates.Conclusions: We report the emergence of the plasmid-mediated oxazolidinone resistance gene poxtA in E. faecium from different farms in China. Comparison of the poxtA genetic context suggests that IS1216E elements play an important role in the dissemination of poxtA. The co-occurrence of poxtA with other antimicrobial and heavy metal resistance genes on the broad-host-range plasmids of the Inc18 family may lead to the co-selection of poxtA, contributing to its persistence and accelerating its dissemination.