2002 Fiscal Year Final Research Report Summary
Role of the efflux proteins in multidrug resistant Haemophilus influenzae
| Project/Area Number |
12670269
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Bacteriology (including Mycology)
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| Research Institution | Kyoto Pharmaceutical University |
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Principal Investigator |
NISHINO Takeshi Kyoto Pharmaceutical University, Department of Microbiology, Professor, 薬学部, 教授 (50097838)
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| Co-Investigator(Kenkyū-buntansha) |
OTSUKI Masako Kyoto Pharmaceutical University, Department of Microbiology, Assistant, 薬学部, 助手 (30121552)
GOTOH Naomasa Kyoto Pharmaceutical University, Department of Microbiology, Associate Professor, 薬学部, 助教授 (30121156)
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| Project Period (FY) |
2000 – 2002
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| Keywords | Haemophilus influenzae / Multidrug resistance / Macrolide antibiotics / Efflux pumps / AcrAB / Specific antibody / MIC / Outer membrane proteins |
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| Research Abstract |
In this study, we tried to determine the role of this acrAB efflux system in the multidrug resistant Haemophilus influenzae. We obtained the acrAB-like gene disruption mutants to study the function of efflux proteins in the resistance of H. influenzae. The MICs of 14- and 15-membered macrolides against these mutants are 4 to 16-fold more susceptible than against parent strain. On the other hand, the MICs of 16-membered macrolides against these mutants are 32 to 64-fold more susceptible than against parent strain. An outer membrane protein associated with the AcrAB system in H. influenzae has not yet been firmly identified. Therefore, we checked the outer membrane protein by computer analysis of whole genome of H. influenzae, and finally found HI1462 protein. And then we got HI1462 disrupted mutant by inserting the kanamycin resistance cartridge into HI1462 gene. The MICs of macrolide and aminoglycoside antibiotics against HI1462 disrupted mutant of H. influenzae are completely similar to MICs of both HI0894- and HI0895-deletion mutants. We made the antibody against AcrAB and HI1462 proteins to examine the expression in clinical isolates of H. influenzae. Our study showed that AcrAB-HI1462 system is normally expressed in H. influenzae ATCC and also wild-type strains. The expression of this efflux system in the wild-type strains produced only a small increase in the MIC. This does not mean, however, that this multidrug efflux system can never make a major contribution to the resistance phenotypes of the organism.
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