Detection and new genetic environment of the pleuromutilinlincosamidestreptogramin A resistance gene lsa(E) in methicillin-resistant Staphylococcus aureus of swine origin
Detection and new genetic environment of the pleuromutilinlincosamidestreptogramin A resistance gene lsa(E) in methicillin-resistant Staphylococcus aureus of swine origin
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猪源耐甲氧西林金黄色葡萄球菌截短侧耳素链霉素A抗性基因lsa(E)的检测及新遗传环境
DOI：
10.1093/jac/dkt015
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发表时间：
2013-06-01
影响因子：
5.2
通讯作者：
Ma, Zhiyong
中科院分区：
文献类型：
--
作者：
Li, Beibei;Wendlandt, Sarah;Ma, Zhiyong
为探讨猪耐甲氧西林金黄色葡萄球菌（MRSA）截短侧耳素耐药的遗传基础，并定位质粒携带耐药基因的遗传环境，对70株对泰妙菌素、伐奈妙林和瑞他莫林具有较高MIC的猪MRSA进行截短侧耳素耐药基因及突变检测。采用葡萄球菌盒式染色体mec（SCCmec）分型、spa分型和多位点序列分型（MLST）进行鉴定。从lsa（E）阳性菌株中提取质粒DNA，并转移到S. aureus RN 4220筛选抗性质粒。对70株MRSA进行了lsa（E）基因区序列测定，并建立了10种重叠PCR方法分析lsa（E）基因的遗传环境，所有菌株均为ST 9（MLST）-t899（spa）-IVa（SCCmec）。16个分离株携带lsa（E）基因;所有其他分离株均对已知截短侧耳素耐药机制呈阴性。在单个分离物中检测到41 kb的lsa（E）携带质粒。序列分析表明，lsa（E）基因位于一个多重耐药基因簇中，与MRSA、甲氧西林敏感的S.金黄色葡萄球菌（MSSA）和粪肠球菌。PCR分析表明，15株MRSA中有6株为多重耐药基因簇的部分缺失，9株为lsa（E）基因的部分缺失，没有已知的侧翼序列。lsa（E）所处的多重耐药基因簇不同于先前在人MRSA/MSSA或大肠杆菌中发现的基因簇。粪便。lsa（E）在多重耐药质粒上的定位有利于其持久存在和传播。
To investigate the genetic basis of pleuromutilin resistance in porcine methicillin-resistant Staphylococcus aureus (MRSA) and to map the genetic environment of the identified plasmid-borne resistance gene.Seventy porcine MRSA isolates, which exhibited high MICs of tiamulin, valnemulin and retapamulin, were investigated for pleuromutilin resistance genes and mutations. They were characterized by staphylococcal cassette chromosome mec (SCCmec) typing, spa typing and multilocus sequence typing (MLST). Plasmid DNA was extracted from the lsa(E)-positive strains and transferred to S. aureus RN4220 for selection of resistance plasmids. The plasmid-borne lsa(E) gene region was sequenced and 10 overlapping PCR assays for the analysis of the genetic environment of lsa(E) were developed.All 70 MRSA isolates were ST9 (MLST)-t899 (spa)-IVa (SCCmec). Sixteen isolates carried the lsa(E) gene; all others were negative for known pleuromutilin resistance mechanisms. An lsa(E)-carrying plasmid of 41 kb was detected in a single isolate. Sequence analysis revealed that the lsa(E) gene was located in a multiresistance gene cluster, which showed partial homology to clusters identified in MRSA, methicillin-susceptible S. aureus (MSSA) and Enterococcus faecalis. PCR analysis of the remaining isolates revealed a partly deleted multiresistance gene cluster in 6/15 isolates and solely the lsa(E) gene without the known flanking regions in 9/15 isolates.We identified the pleuromutilinlincosamidestreptogramin A resistance gene lsa(E) in porcine MRSA isolates. The multiresistance gene cluster in which lsa(E) was located differed from the previously described ones found in human MRSA/MSSA or in E. faecalis. The location of lsa(E) on a multiresistance plasmid facilitates its persistence and dissemination.