2005 Fiscal Year Final Research Report Summary
Observation with time of the rise and fall of community-acquired MRSA and its pathogenicinvestigation
| Project/Area Number |
14370097
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | JUNTENDO UNIVERSITY |
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Principal Investigator |
HIRAMATSU Keiichi Juntendo University, Bacteriology, professor, 医学部, 教授 (10173262)
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| Co-Investigator(Kenkyū-buntansha) |
KUWAHARA Kyoko Juntendo University, assistant professor, 医学部, 助手 (10167976)
YAMAMOTO Munetaka Juntendo University, assistant professor, 医学部, 助手 (50338414)
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| Project Period (FY) |
2002 – 2005
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| Keywords | Community aquired MRSA / Hospital MRSA / Healthy children / Healthy / SCC mec / MLST / PFGE / Coagulase typing |
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| Research Abstract |
We collected nasal samples from 818 children at 6 day care centers and 2 kindergartens of three districts, Miyagi, Kyoto and Saga during June 2001 and Nov.2002. And also we collected nasal samples from 271 medical students with no clinical experience and 86 nurses, during 2003 and 2005.
Findings : Among 818 children, 35 children (4.3%) carried MRSA and 231 children (28.2%) carried methicillin-resistant coagulase-negative staphylococci (MRC-NS). 2 students (0.7%) and 3nurses (3.5%) carried MRSA and 123 students (45.4%) and 63 nurses (73.3%) carried MRC-NS. The types of staphylococcal cassette chromosome mec (SCCmec) found among 44 MRSA isolates from children were as follows : type IIa, 11 isolates ; type IIb, 19 isolates ; type IV, 14 isolates. The type IIb SSCmec element was a new SCCmec element found in this study. Eleven (25%) strains which belonged to clonal complex 5 (CC5) carried type IIa SCCmec, and they produced type 2 coagulase and toxic shock syndrome toxin 1. They were indistinguishable from hospital-aquired MRSA or health care-associated MRSA (H-MRSA) strains in Japan, represented by strain N315. On the other hand, 33 (75%) strains, most of which belonged to CC78 or CC91, carried small SCCmec elements, such as type IIb or type IV, and they produced type 1 or type 3 coagulase and exofoliative toxin. Among 135 MR-epidermidis isolated from healthy Japanese students and nurse, most prevalent SCCmec type were type IV SCCmec (120 strains, 88.9%). Conclusions : We found that MRSA are already prevalent among healthy children and healthy students, and also MRC-NS are prevalent among healthy children, students and especially nurse. The fact that type IV MRC-NS strains were prevalent in the community suggested that they might serve as a reservoir for the SCCmec element carried by MRSA strains disseminated in the community.
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