| Project/Area Number |
10670555
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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 |
Respiratory organ internal medicine
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| Research Institution | University of the Ryukyus |
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Principal Investigator |
SAITO Atsushi University of the Ryukyus, Faculty of Medicine, Professor, 医学部, 教授 (90039842)
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| Co-Investigator(Kenkyū-buntansha) |
TOYODA Kazumasa University of the Ryukyus, University Hospital, Resident, 医学部・附属病院, 医員
KUSANO Nobuchika University of the Ryukyus, University Hospital, Assistant, 医学部・附属病院, 助手 (30195424)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1999: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1998: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Streptococcus milleri group / anaerobe / normal flora / synergistic effect / capsule / pneumonia / abscess / diagnostic method / ストレプトコッカス ミレリ / 血液寒天培地 / 肺化膿症 / 膿胸 / 相乗効果 |
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| Research Abstract |
Streptococcus milleri group and anaerobes, recognized as normal flora in the mouth, were proved to be isolated from the patients of acute pneumonia, lung abscess and thoracic empyema by the methods of transthoracic needle aspiration, which could prevented the causative organisms from contamination with normal flora. This suggested that S. milleri group and anaerobes were important causative organisms in pulmonary infections.
Studies on the mechanisms of their pathogenicity in the mice model of pneumonia showed that the higher mortality, longer survival in the lungs and more severe pathohistological changes in the mixed infection of S. milleri group and anaerobes than in the single infection, respectively. This suggested that there may be a synergistic effect between S. milleri group and anaerobes.
In vitro studies demonstrated that S. milleri group strains isolated from the infectious lesions had stronger ability to inhibit the function of phagocytosis and phagocytic killing of human leukocytes against S. milleri group than that from normal flora. The degree of the inhibition depended on the presence of capsule of the bacteria. The addition of capsular material, mainly composed of mucopolysaccharide, could also inhibited the neutrophil function of phagocytic killing against S. milleri group. The presence of capsular material might be a pathogenicity of S. milleri group strains. On the other hand, the metabolic substances of anaerobes, short-chain fatty acids, inhibited the neutrophil function of phagocytosis and phagocytic killing against bacteria, while they could promoted the growth of S. milleri group.
The problems from the view of clinical microbiology was the isolation and identification of S. milleri group. It was elucidated that it depended on what kind of blood agar plate and identification kit used.
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