Research of vancomycin resistance, adherence factors, and conjugative plasmids of enterococci

(1)共检测了640株万古霉素耐药屎肠球菌（VRE）分离株的接合性庆大霉素耐药质粒。492株（77%）菌株对64 mg/ml（MIC）至1024 mg/ml（MIC）以上浓度的庆大霉素表现出耐药性。在492株庆大霉素耐药菌株中，有261株（53%）的庆大霉素耐药性转移到了大肠杆菌中.在肉汤交配中，以每个供体细胞约10 - 10 μ g的频率感染屎肠菌菌株<-5><-6>。鉴定了接合性庆大霉素抗性质粒，并根据其EcoRI限制性图谱将其分为五种类型（A至E）。每种质粒的EcoRI或NdeI限制性片段与接合性庆大霉素抗性质粒pMG 1（65.1kb）杂交，所述接合性庆大霉素抗性质粒pMG 1最初从大肠杆菌中分离。粪菌临床分离株，并在肉汤交配中有效转移。(2)通过扫描检测粪肠球菌菌株对人T24细胞的粘附 关于我们 电镜从30株泌尿系感染患者尿液中分离出5株高粘附性菌株。这五个分离的菌株也有效地粘附到人膀胱上皮细胞。用纤连蛋白或胰蛋白酶处理这些菌株的粘附被抑制，这意味着细菌细胞表面上的特定蛋白质（粘附素）介导粘附到宿主细胞表面上的纤连蛋白，并且粘附素不同于已报道的粘附素。(3)pMG 1（65.1 kbp）是一种非信息素依赖性屎肠球菌接合质粒，赋予庆大霉素抗性。为了分析tra基因在pMG 1中表达的调节，在接合期间检查pMG 1的转录物。交配开始后20 min，71 ORF 2基因的一个转录本水平达到最高。在供体细胞或受体细胞的培养物中未观察到这种增加。在肉汤交配中，pMG 229（其pMG 1上的71 ORF 2基因被破坏）或亲本pMG 1的转移频率分别为1.6 × 10 ~（-4）<-7>和1.1 × 10 ~<-3>（-4）/供体细胞;在过滤交配中，pMG 229和pMG 1的转移频率分别为2.7 × 10 ~（-4）<-3>和8.5 × 10 ~<-2>（-4）/供体细胞。71 ORF 2是一个参与接合作用的tra基因系统的基因，其产物与肉汤交配过程中交配聚集体的形成或稳定有关。少

(1) A total of 640 vancomycin resistant Enterococcus faecium (VRE) isolates were examined for the conjugative gentamicin resistance plasmid. Four hundred ninety-two (77 %) of the strains exhibited resistance to concentrations of gentamicin from 64 mg/ml (MIC) to greater than 1024 mg/ml (MIC). The gentamicin resistance of each of 261 (53 %) of the 492 gentamicin resistant strains was transferred to E. faecium strain at a frequency of about 10^<-5> to 10^<-6> per donor cell in broth mating. The conjugative gentamicin resistance plasmids were identified and were classified into five types (A through E) with respect to their EcoRI restriction profiles. The EcoRI or NdeI restriction fragments of each type of plasmids hybridized to the conjugative gentamicin resistance plasmid pMG1 (65.1 kb), which was originally isolated from an E. faecium clinical isolate, and transfer efficiently in broth mating.(2) The adherence of Enterococcus faecalis strains to human T24 cells was examined by scanning … More electron microscopy. Five highly adhesive strains were identified from 30 strains isolated from the urine of patients with urinary tract infections. The five isolated strains also adhered efficiently to human bladder epithelial cells. The adhesiveness of these strains was inhibited by treatment with fibronectin or trypsin, implying that a specific protein (adhesin) on the bacterial cell surface mediates adherence to fibronectin on the host cell surfaces, and the adhesin differs from the reported adhesins.(3) pMG1 (65.1 kbp) is a pheromone-independent Enterococcus faecium conjugative plasmid conferring gentamicin resistance. To analyze the regulation of tra gene expression in pMG1, transcripts of pMG1 were examined during conjugation. One transcript of gene 71ORF2 increased to its maximum level at 20 min after the start of mating. This increase was not observed in cultures of the donor cell or recipient cell. The transfer frequency of the mutant plasmid pMG229, which had a disrupted 71ORF2 gene on pMG1, or the parent pMG1 was 1.6x10^<-7> or 1.1x10^<-3> per donor cell, respectively, in broth mating, and the transfer frequency of pMG229 and pMG1 was 2.7x10^<-3> or 8.5x10^<-2> per donor cell, respectively, in filter mating. 71ORF2 is a gene involved in the tra gene system for conjugation, and the product of the gene was associated with the formation or stabilization of mating aggregates during broth mating. Less