高齢者福祉施設における室内環境に関する研究: 第1報-遺伝子解析法を用いた微生物汚染実態詳細調査の結果

摘要

現在総人口に占める65歳以上人口の割合(高齢化率)は25.1%に達しており、今後さらに高齢社会に進むと予想されている。一般的に高齢者は免疫力が低下しているため、いわゆる日和見感染症にり患しやすい。したがって、高齢者が使用•利用する高齢者福祉施設内における空気環境、とりわけ微生物汚染の実態を解明し、問題があればその対策を検討する必要がある。本報では、高齢者福祉施設內の微生物汚染について、季節別、時間帯別の詳細な測定を行い、加えてDNA解析手法を用いることにより、次の事柄が明らかになった。①多数の人が集まるディルーム内の浮遊細菌と浮遊真菌濃度の1日の変動幅は2～3桁にも達しており、スポット的な立ち入り測定では、室内細菌•真菌の汚染の実態を把握することが難しい。②浮遊微生物（細菌+真菌）濃度については、一施設を除けば、75%タイル値が日本建築学会の規準値500cfu/m~3を満足していたが、多種の日和見感染菌が検出されており、その対策を施すことが望まれる。%In Japan, the rate of the 65 and over years-old (rate of aging) population occupied to the present overall population has reached to 25.1% in 2013, and this is expected to progress to becoming an aged society hereafter. In general, as the immunity of aged people is quite low, they tend to suffer from so-called opportunistic infections. Therefore, it is important to examine indoor air environments of welfare facilities for the aged. If there are problems in particular on the actual status of microbial contamination, it is necessary to examine the countermeasures. In this study, the environments of eight rooms of 5 facilities were examined. The sites or investigation include the day room where inhabitants gather, the room where the facility residents stayed for a long time, and the outdoor. Measurements were carried out twice at each site from August to October 2011 (summer), and January to February 2012 (winter). Furthermore, to clarify the time-dependent-change-changes in the characteristics with regard to both the indoor airborne microbial concentration and the type of species, the environments of the day rooms were continually evaluated during summer, in terms of airborne bacteria and airborne fungi. The detailed analysis of microbial contamination using the DNA analysis technique revealed, the following findings: (1) The range of fluctuation of concentration the airborne bacteria and fungi in the day room has increased 100 to 1000 fold, and it is difficult to grasp the actual condition of contamination of indoor bacteria and fungi by a momentary measurement. (2) Except at one facility, 75 percentile of the airborne microbial concentration (including bacteria and fungus) in 4 facilities of the Architectural Institute of Japan satisfied the standard value of 500 cfu/m~3, but various bacilli causing opportunistic infections, such as Staphylococcus hominis, S. epidermidis, Serratia marcescens, Corynebacterium xerosis, C.freneyi, Acinetobacter baumannii, A. calcoaceticus, Stenotrophomonas maltophilia, are detected. (3) Since many opportunistic infection-causing bacteria exist in these welfare facilities, preventive measures are required to ensure safety of the aged people who have special care requirements.