D-Ala-D-Ser VanN-Type Transferable Vancomycin Resistance in Enterococcus faecium
D-Ala-D-Ser VanN-Type Transferable Vancomycin Resistance in Enterococcus faecium
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DOI：
10.1128/aac.00714-11
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发表时间：
2011-10-01
影响因子：
4.9
通讯作者：
Cattoir, Vincent
中科院分区：
文献类型：
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作者：
Lebreton, Francois;Depardieu, Florence;Cattoir, Vincent
从血培养物中分离的屎肠球菌UCN 71对低水平万古霉素耐药（MIC，16 μ g/ml），但对替考拉宁敏感（MIC，0.5 μ g/ml）。用特异于前述糖肽抗性连接酶基因的引物未观察到扩增，但用简并引物获得对应于称为vanN的基因的PCR产物并测序。推导的VanN蛋白与D-丙氨酸：D-丝氨酸VanL连接酶有关（65%同一性）。vanN基因簇的组织，确定使用简并引物和热不对称交错（TAIL）-PCR，是类似的vanC操纵子。通过cDNA末端快速扩增（RACE）-PCR鉴定了抗性操纵子上游的单个启动子。在不存在万古霉素的情况下，以D-丝氨酸和D，D-肽酶活性结束的肽聚糖前体的存在表明抗性操纵子的组成型表达。VanN型抗性可通过与E.屎室这是第一次在大肠杆菌中发现可转移的D-Ala-D-Ser型耐药。屎室
Enterococcus faecium UCN71, isolated from a blood culture, was resistant to low levels of vancomycin (MIC, 16 mu g/ml) but susceptible to teicoplanin (MIC, 0.5 mu g/ml). No amplification was observed with primers specific for the previously described glycopeptide resistance ligase genes, but a PCR product corresponding to a gene called vanN was obtained using degenerate primers and was sequenced. The deduced VanN protein was related (65% identity) to the D-alanine: D-serine VanL ligase. The organization of the vanN gene cluster, determined using degenerate primers and by thermal asymmetric interlaced (TAIL)-PCR, was similar to that of the vanC operons. A single promoter upstream from the resistance operon was identified by rapid amplification of cDNA ends (RACE)-PCR. The presence of peptidoglycan precursors ending in D-serine and D, D-peptidase activities in the absence of vancomycin indicated constitutive expression of the resistance operon. VanN-type resistance was transferable by conjugation to E. faecium. This is the first report of transferable D-Ala-D-Ser-type resistance in E. faecium.