Vancomycin-resistance Transferability from VanA Enterococci to Staphylococcus aureus
Vancomycin-resistance Transferability from VanA Enterococci to Staphylococcus aureus
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DOI：
10.1007/s00284-011-9868-6
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发表时间：
2011-05-01
影响因子：
2.6
通讯作者：
Anacarso, Immacolata
中科院分区：
文献类型：
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作者：
de Niederhaeusern, Simona;Bondi, Moreno;Anacarso, Immacolata
近十年来，甲氧西林耐药的金黄色葡萄球菌出现了高水平的万古霉素耐药(VRSA)，感染VRSA的患者一般也会同时感染耐万古霉素的肠球菌(VRE)。鉴于VRSA分离株对万古霉素的高度耐药可能与共感染VRE菌株中含有Vana基因的Tn1546转座子水平转移有关，作者研究了这种耐药从VaNA肠球菌到金黄色葡萄球菌的“体外”接合转移。在25个配对中，5个万古霉素耐药的肠球菌作为供体(3个粪肠球菌和2个粪肠球菌)，5个金黄色葡萄球菌作为受体，均为临床分离株，其中2个成功地使用粪肠球菌作为供体。Vana基因扩增证实了万古霉素耐药基因在两个接合子中的转移，并且与各自的VRE供体(MIC和GT；128µg/ml)相比，其抗性表达水平较低(MIC为32mU/ml)。即使在含有万古霉素亚抑制水平的MSA平板上连续传代过夜后，转接子对万古霉素的耐药性仍保持不变。这项研究表明，VANA基因转移可以通过“体外”技术实现，而不需要使用实验室动物作为转接生长的底物，这是其他作者之前唯一进行的类似实验。此外，在先前的实验中，与本研究相反，万古霉素抗性金黄色葡萄球菌转接合子是在红霉素琼脂上选择的，而不是通过万古霉素琼脂直接选择的。
In last decade methicillin-resistant Staphylococcus aureus with high level of vancomycin-resistance (VRSA) have been reported and generally the patients with VRSA infection were also infected with a vancomycin-resistant Enterococcus (VRE). Considering that the high level of vancomycin-resistance in VRSA isolates seems to involve the horizontal transfer of Tn1546 transposon containing vanA gene from coinfecting VRE strains, the authors have studied the "in vitro" conjugative transfer of this resistance from VanA enterococci to S. aureus. Out of 25 matings performed combining five vancomycin-resistant enterococci as donors (three Enterococcus faecalis and two Enterococcus faecium), and five S. aureus as recipients, all clinical isolates, two have been successful using E. faecalis as donor. The transfer of vancomycin-resistance was confirmed by vanA gene amplification in both transconjugants and the resistance was expressed at lower levels (MIC 32 mu g/ml) in comparison with the respective VRE donors (MIC > 128 mu g/ml). The vancomycin-resistance of trasconjugants was maintained even after subsequent overnight passages on MSA plates containing subinhibitory levels of vancomycin. This study shows that the vanA gene transfer can be achieved through techniques "in vitro" without the use of laboratory animals employed, in the only similar experiment previously carried out by other authors, as substrate for the trasconjugant growth. Moreover, in that previous experiment, contrary to this study, the vancomycin resistant S. aureus trasconjugants were selected on erythromycin agar and not by direct vancomycin agar selection.