Isolation of VanB-Type Enterococcus faecalis Strains from Nosocomial Infections: First Report of the Isolation and Identification of the Pheromone-Responsive Plasmids pMG2200, Encoding VanB-Type Vancomycin Resistance and a Bac41-Type Bacteriocin, and pMG2201, Encoding Erythromycin Resistance and Cyt
Isolation of VanB-Type Enterococcus faecalis Strains from Nosocomial Infections: First Report of the Isolation and Identification of the Pheromone-Responsive Plasmids pMG2200, Encoding VanB-Type Vancomycin Resistance and a Bac41-Type Bacteriocin, and pMG2201, Encoding Erythromycin Resistance and Cyt
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DOI：
10.1128/aac.00754-08
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发表时间：
2008-11
影响因子：
4.9
通讯作者：
B. Zheng;H. Tomita;Takako Inoue;Y. Ike
中科院分区：
文献类型：
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作者：
B. Zheng;H. Tomita;Takako Inoue;Y. Ike
对来自不同住院患者的18株相同的万乙型粪肠球菌进行了细菌耐药性和质粒型DNA检测。其中12株对红霉素(Em)、庆大霉素(GM)、卡那霉素(Km)、四环素(TC)、万古霉素(Van)耐药，对粪肠球菌产生溶细胞素(Hly/Bac)和细菌素(Bac)。另有6株菌株对GM、KM、TC和VAN具有耐药性，并产生细菌素。通过肉汤交配，将EM和Van抗性分别转移到粪肠球菌FA2-2菌株中，转移频率约为10−4/供体细胞。Em抗性接合子和Van抗性接合子分别含有一个65.7kbp和106kbp的质粒。从粪肠球菌代表菌株NKH15中分离到的106-kBP和65.7-kBP两个质粒分别命名为pMG2200和pMG2201。PMG2200赋予宿主菌株对万古霉素的抗性和细菌素活性，并对合成信息素cCF10对pCF10作出反应；pMG2201对其宿主菌株产生红霉素抗性和溶细胞素活性，对合成信息素cAD1对PAD1做出反应。PMG2200的DNA全序列(106,527个碱基)表明，该质粒含有编码vanB2型抗性的类Tn1549元件和信息素反应质粒pYI14的类Bac41细菌素基因。该质粒含有信息素反应质粒中的调控区，编码基因prgX和prgQ，这两个基因是pCF10的关键负调控元件。PMG2200还编码了PAD1的关键正调控因子TraE1，这表明pMG2200是一个自然产生的嵌合质粒，其结果是在信息素反应的调节区有一个PRGX-prgQ-TraE1遗传组织。PMG2200的ORIT功能区和可能的松弛酶基因与pCF10和PAD1不同。PMG2200的松弛酶被归类为MOBMG家族的成员，发现于pMG1样载体的信息素非依赖质粒β中。这是首次分离和鉴定编码VanB抗性的信息素响应型高结合质粒。
ABSTRACT Eighteen identical VanB-type Enterococcus faecalis isolates that were obtained from different hospitalized patients were examined for their drug resistance and plasmid DNAs. Of the 18 strains, 12 strains exhibited resistance to erythromycin (Em), gentamicin (Gm), kanamycin (Km), tetracycline (Tc), and vancomycin (Van) and produced cytolysin (Hly/Bac) and a bacteriocin (Bac) active against E. faecalis strains. Another six of the strains exhibited resistance to Gm, Km, Tc, and Van and produced a bacteriocin. Em and Van resistance was transferred individually to E. faecalis FA2-2 strains at a frequency of about 10−4 per donor cell by broth mating. The Em-resistant transconjugants and the Van-resistant transconjugants harbored a 65.7-kbp plasmid and a 106-kbp plasmid, respectively. The 106-kbp and 65.7-kbp plasmids isolated from the representative E. faecalis NKH15 strains were designated pMG2200 and pMG2201, respectively. pMG2200 conferred vancomycin resistance and bacteriocin activity on the host strain and responded to the synthetic pheromone cCF10 for pCF10, while pMG2201 conferred erythromycin resistance and cytolysin activity on its host strain and responded to the synthetic pheromone cAD1 for pAD1. The complete DNA sequence of pMG2200 (106,527 bp) showed that the plasmid carried a Tn1549-like element encoding vanB2-type resistance and the Bac41-like bacteriocin genes of pheromone-responsive plasmid pYI14. The plasmid contained the regulatory region found in pheromone-responsive plasmids and encoded the genes prgX and prgQ, which are the key negative regulatory elements for plasmid pCF10. pMG2200 also encoded TraE1, a key positive regulator of plasmid pAD1, indicating that pMG2200 is a naturally occurring chimeric plasmid that has a resulting prgX-prgQ-traE1 genetic organization in the regulatory region of the pheromone response. The functional oriT region and the putative relaxase gene of pMG2200 were identified and found to differ from those of pCF10 and pAD1. The putative relaxase of pMG2200 was classified as a member of the MOBMG family, which is found in pheromone-independent plasmid pHTβ of the pMG1-like plasmids. This is the first report of the isolation and characterization of a pheromone-responsive highly conjugative plasmid encoding vanB resistance.