| Project/Area Number |
15590409
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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 | Saga University (2005)
University of Occupational and Environmental Health, Japan (2003-2004) |
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Principal Investigator |
MIYAMOTO Hiroshi Saga University, FACULTY OF MEDICINE, PROFESSOR, 医学部, 教授 (40229894)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2005: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Legionella / VBNC / pathogenicity / virulence / bath / cooling tower / pneumonia / 給湯設備 / 培養不能菌 |
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| Research Abstract |
Legionella pneumophila is an aquatic bacterium and is responsible for Legionnaires' disease in humans. Free-living amoebae are parasitized by legionellae and provide the intracellular environment required for the replication of this bacterium. In low-nutrient environments, however, L.pneumophila is able to enter a non-replicative viable but nonculturable (VBNC) state. Ecological studies on Legionella spp. are essential to better understand their sources in the natural environments, the mechanism of their entry into man-made water systems and the fact ors enabling their survival and growth in aquatic habitats. In this study, L.pneumophila JLP1087 was suspended in PBS containing chlorine at 10(7) cells/ml. The decreasing number of bacteria was monitored by CFU measurements, CFDA direct counts, and EtBr direct counts. After 23 mins of incubation in the PBS, the cells were no longer culturable on routine plating media ; however, they were still detectable by CFDA. The addition of Acanthamoeba culbertosoni to the dormant bacteria resulted in the resuscitation of L.pneumophila JLP1087 to a culturable state. The VBNC Legionella were intraperitoneally infected to guinea pigs, which is considered a parameter for virulence. The infected guinea pig developed no fever and no weight loss, suggesting that the VBNC loses their virulence.
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