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Yasuyoshi Ike

Publications and source records attributed to Yasuyoshi Ike.

8 recordsLinked to original sources
PubMed2004

Tissue-specific adherent Enterococcus faecalis strains that show highly efficient adhesion to human bladder carcinoma T24 cells also adhere to extracellular matrix proteins.

The ability of Enterococcus faecalis clinical isolates to adhere to immobilized extracellular matrixes (ECMs) coating the walls of microtiter plates was examined by microscopy. The ECMs consisted of fibronectin, laminin, collagen types I, II, IV, and V, fibrinogen, and lactoferrin. With the exception of fibrinogen, each isolate showed a different level of adherence to each of the ECMs. No significant level of adherence to fibrinogen was observed for any isolate. The tissue-specific adhesive strains AS11, AS12, AS14, AS15, HT11, and HT12, which showed highly efficient adherence to human bladder carcinoma T24 cells and human bladder epithelial cells, showed strong adherence to fibronectin, laminin, and collagen type I, II, IV, and V ECMs, and the levels were greater than 10(4) cells/mm2 of well surface coated by ECM. None of the isolates that showed little adherence to human bladder carcinoma T24 cells showed efficient adherence to all the ECMs. The levels of adherence of gelatinase-producing isolates to the collagens were lower than the levels of adherence of gelatinase-negative isolates. When tissue-specific adhesive strains that adhered strongly to each ECM were preincubated with fibronectin, the adherence of the strains to fibronectin was inhibited, but the adherence of the strains to collagen type IV was not inhibited. Likewise, preincubation with collagen type IV inhibited adherence to collagen type IV but not adherence to fibronectin. All of the E. faecalis isolates were shown to carry the ace gene by PCR analysis performed with specific primers for collagen binding domain A of ace. The ace gene encodes Ace (adhesin of collagen from enterococci). The prtF gene of group A streptococci, which encodes the fibronectin binding protein of group A streptococci, was not detected in the tissue-specific adhesive strains by Southern analysis performed with the prtF probe of the Streptococcus pyogenes JRS4 strain. Mutants with altered collagen binding were isolated by insertion of Tn916 into the chromosome of tissue-specific adhesive strain AS14. The number of mutant adhesive bacterial cells that adhered to collagen and also to laminin was 1 or 2 orders lower than the number observed for the wild-type strain, but the level of adherence to fibronectin remained the same as that of the wild-type strain.

ATP-Binding Cassette Transporters↗
PubMed2003

Highly conjugative pMG1-like plasmids carrying Tn1546-like transposons that encode vancomycin resistance in Enterococcus faecium.

A total of 12 VanA-type vancomycin-resistant enterococci, consisting of 10 Enterococcus faecium isolates and two Enterococcus avium isolates, were examined in detail. The vancomycin resistance conjugative plasmids pHTalpha (65.9 kbp), pHTbeta (63.7 kbp), and pHTgamma (66.5 kbp) were isolated from each of three different E. faecium strains. The plasmids transferred highly efficiently between enterococcus strains during broth mating and were homologous with pMG1 (Gm(r); 65.1 kb).

Anti-Bacterial Agents↗
PubMed2002

Vancomycin-resistant enterococci in humans and imported chickens in Japan.

The phenotypes and genotypes of 22 VanA-type vancomycin-resistant enterococci that had been isolated in Japan were examined. The VanA resistance determinant was plasmid mediated in each of the 22 strains. Of the 22 strains, 8 were isolated from different patients and 11 and 3 were obtained from different samples of chickens imported from Thailand and France, respectively. Three of the strains that were isolated from patients and the 11 strains isolated from the Thai chickens showed high-level vancomycin resistance (MICs, 512 to 1,024 micro g/ml) and low-level teicoplanin resistance (MICs, 0.5 to 4 micro g/ml). Each of these strains had three amino acid substitutions in the N-terminal region of the deduced VanS sequence. L50 was converted to V, E54 was converted to Q, and Q69 was converted to H compared to the vanS gene sequence of Tn1546.

Animals↗
PubMed2002

Analysis of the conjugal transfer system of the pheromone-independent highly transferable Enterococcus plasmid pMG1: identification of a tra gene (traA) up-regulated during conjugation.

pMG1 (65.1 kbp) is a pheromone-independent Enterococcus faecium conjugative plasmid conferring gentamicin resistance. pMG1 is able to transfer to enterococci at a high frequency in broth mating experiments, and it does not respond to the sex pheromones which are involved in the high-frequency transfer system of some conjugative plasmids in Enterococcus faecalis. To analyze regulation of tra gene expression in pMG1, transcripts of pMG1 were examined during conjugation. RNA samples were prepared from mating mixtures 20, 40, 80, and 160 min after initiation of mating and were subsequently analyzed by Northern hybridization by using a variety of pMG1 DNA fragments as probes. One transcript of gene 71ORF2 increased to the maximal level 20 min after the start of mating. The level of this transcript decreased after 40 min of mating to the same level as the level in the control donor culture. The increase was not observed in cultures of the donor cells or recipient cells. These findings suggested that the increase was a conjugation-specific event. The 71ORF2 gene of pMG1 was disrupted by using the suicide vector pMG226 carrying an erythromycin resistance gene that is expressed in enterococci. The transfer frequencies of mutant plasmid pMG229, which had a disrupted 71ORF2 gene in pMG1, and the parent plasmid pMG1 were 1.6 x 10(-7) and 1.1 x 10(-3) per donor cell, respectively, in broth mating experiments, and the transfer frequencies of pMG229 and pMG1 were 2.7 x 10(-3) and 8.5 x 10(-2) per donor cell, respectively, in filter mating experiments. This indicated that the transfer frequency of plasmid pMG229 was reduced during broth mating and was not altered during filter mating. 71ORF2, which is designated traA, is a gene involved in the tra gene system for conjugation, and the product of this gene is associated with the formation or stabilization of mating aggregates during broth mating.

Base Sequence↗
PubMed2002

Possible connection between a widely disseminated conjugative gentamicin resistance (pMG1-like) plasmid and the emergence of vancomycin resistance in Enterococcus faecium.

A total of 640 vancomycin-resistant Enterococcus faecium (VRE) isolates, which were obtained between 1994 and 1999 from the Medical School Hospital of the University of Michigan, Ann Arbor, were used in this study. Of the 640 strains, 611 and 29 were VanA and VanB VRE, respectively, based on PCR analysis. Four hundred ninety-two (77%) of the strains exhibited resistance to concentrations of gentamicin from 64 micro g/ml (MIC) to more than 1,024 micro g/ml (MIC). The gentamicin resistance of each of 261 (53%) of the 492 gentamicin-resistant strains was transferred to E. faecium at a frequency of about 10(-5) to 10(-6) per donor cell in broth mating. More than 90% of vancomycin resistances of the 261 strains cotransferred with the gentamicin resistances to E. faecium strains by filter 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 transfer frequencies of each type of plasmid between E. faecium strains or Enterococcus faecalis strains were around 10(-3) to 10(-5) per donor cell or around 10(-6) to 10(-7) per donor cell, respectively, in broth mating. Type A and type B were the most frequently isolated, at an isolation frequency of about 40% per VRE isolate harboring the gentamicin resistance conjugative plasmid. The plasmids did not show any homology in Southern hybridization with the pheromone-responsive plasmids and broad-host-range plasmids pAMbeta1 and pIP501. 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.

Anti-Bacterial Agents↗