| Project/Area Number |
05304028
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Bacteriology (including Mycology)
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| Research Institution | Tokai University |
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Principal Investigator |
NAKAE Taiji Tokai Univ., Sch.of Med., Professor, 医学部, 教授 (50102851)
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| Co-Investigator(Kenkyū-buntansha) |
HIRAMATSU Keiichi Juntendo Univ., Sch.Med., Professor., 医学部, 教授 (10173262)
GOTOH Naomasa Kyoto Pharm.Univ., Associate Professor, 薬学部, 講師 (30121560)
YAMAGUCHI Akihito Osaka Univ.Inst.Indst.Sci., Professor, 産業科学研究所, 教授 (60114336)
INOUE Matsuhisa Kitasato Univ., Sch.Med.Professor, 薬学部, 教授 (10008336)
IYOBE Shizuko Gunma Univ., Sch.Med., Associate Professor, 医学部, 助教授 (90008318)
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| Project Period (FY) |
1993 – 1995
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| Keywords | drug resistance / bacteria / membrane / permeability / extrusion pump / active afflux / antibiotic target / beta-lactamase |
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| Research Abstract |
Antibiotic susceptibility of bvacterial cells may be determined by several factors including the outer membrane permiability, active drug efflux, interplay of the antibiotic modifying enzyme or altered target sensitivity with the membrane permiability. This project team focused her studies on these problems.
1. Outer membrane permeability and antibiotic susceptibility. (1) We studied role of the Pseudomonas porins on the antibiotic susceptiblity constructing chromosomal deletions of single or muliple porin gene (s). Susceptibility of porin-deletion mutants to most antibiotics tested was unchanged except that all the potein D-deletion mutant showed 8-fold elevated MIC.(2) It was found that high imipenem resistance could be achieved by the interplay of protein D deficiency and beta-lactamase production. In the beta-lactamase induction, it is likely that products of the penicillin inding protein (s) wrer involved.
2. We discovered that active antibiotic extrusion from the cells are a major
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factor of antibiotic resistance. (1) We cloned, sequenced and identified genes coded for an antibiotic extrusion machinery (mex gene) in Pseudomonas aeruginosa. (2) Multiple antibiotic sresistance in P.aeruginosa was found to be attributable to high expression of the operon. (3) Amino acid residues responsible for the tetracycline extrusion in Escherichia coli were identified by the cite-directed mutagenesis and that was found to be acidic amino acid residues. (4) Interplay of the antibiotic extrusion system such as nfxB and nfxC with target alteration resulted in high quinolone resistance.
3. Problems of antibiotics and disinfectant tesistance Staphylococcus were subject of present study. (1) We studied how the mec A gene was integrated into MRSA chromosome and found that mexA was intgrated at specific sites of the chromosome. For the expression of mec operon, it was discovered that two regulatory genes were involbed. (2) We have screened the genes coded for the disinfectant extrsion proteins and found that all Staphylococcus conerved the gene.Search of homologue gene coded for the disinfectnt extrusion protein was extended to P.aeruginosa and E.coli and found that these bacteria possess qac E hmologue. (3) Structures of membrane damaging pathogenic factors of MRSA,leucocidin and gamma-hemolysine were analyzed and found that these toxins shares one of the subunit proteins. Amino acid residues of this protein responsible for leucocidin and gamma-hemolysine function were determined.
This project team studied role of membranes in the antibiotic resistance in bacteria and largly contribute to understanding of the mechaism of antibiotic rsistance in which the membrane function is involved. It was timely to organize this collaborative working team, since past few years were the time that impotance of membrane functions in antibioti resistance was rcognized world wide. Less
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