2006 Fiscal Year Final Research Report Summary
Experimental aspiration pneumonia induced by human supragingival dental plaque in mice
| Project/Area Number |
17592185
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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 |
Social dentistry
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| Research Institution | Kagoshima University |
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Principal Investigator |
NAGATA Emi Kagoshima University, Medical and Dental Hospital, Research Associate, 医学部・歯学部附属病院, 助手 (00304816)
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| Co-Investigator(Kenkyū-buntansha) |
KITADA Katsuhiro Kagoshima University, Graduate School of Medical and Dental Sciences, Research Associate, 大学院医歯学総合研究科, 助手 (90195264)
OHO Takahiko Kagoshima University, Graduate School of Medical and Dental Sciences, Professor, 大学院医歯学総合研究科, 教授 (50160940)
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| Project Period (FY) |
2005 – 2006
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| Keywords | dental plaque / aspiration pneumonia / oral bacteria / mouse |
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| Research Abstract |
Human dental plaque consists of a wide variety of microorganisms, some of which are believed to cause systemic infections, including aspiration pneumonia. To confirm this hypothesis experimentally, we examined the pneumonia-inducing ability of dental plaque in mice, the microbial features of the infectious locus produced by the plaque. Aliquots of a suspension of supragingival dental plaque containing 1 x 10^7 CFU of bacteria were delivered into the lower part of the trachea of mice. All mice exhibited signs of illness immediately after inoculation such as ruffled fur, labored respiration, and appeared waste. In total, 12 out of 18 mice (66.7%) died within 3 days after inoculation with dental plaque suspension. All the 3 human dental plaque samples tested induced pneumonia in mice. Bacterial cells were recovered from the lungs of all the mice that died, and the number was 4.44 ± 0.77 log_<10>CFU/mg of lung. From 5 out of 6 survived mice, bacterial cells were recovered from the lungs and the number was 0.38±0.38 log_<10>CFU/mg of lung. Various microbial species were recovered from infected lungs examined, and no characteristic bacterial distribution was observed both in the survived mice and the mice that died within 3 days after plaque inoculation. Representative isolates of Streptococcus oralis, Streptococcus intermedius and Gemella morbillorum recovered from lungs showed ability to induce pneumonia, respectively. These results suggest that human supragingival dental plaque is a source of the infectious pathogens that cause pneumonia.
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