汚染指標菌としてのEscherichia coliに関する実験疫学的研究
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概要
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Demonstration of bacteria of the coliform group from food and drink indicates the possibility of fecal contamination by pathogenic organism. Despite many reports available on contamination by coliform bacteria, demonstration of bacteria of coliform group does not definitely prove fresh fecal on human contamination, since no agreement is generally seen between the pattern of bacterial flora in feaces and that in the test materials in many reports. Therefore since E. coli is considered as occupying the top position of enterobacterial fiora it may be used as the bacterial indicator of contamination. We have studied the development of fecal contamination in vivo in a group of mice after excretion in terms of experimental epidemiology. One group of 5-10 mice were maintained in a single cage to follow the changes in their bacterial flora. Through comparison with the isolated organism, a mutual exchange of bacterial flora was demonstrated among the various mice, after contact for 3-6 days. Such exchange readily occurred with some bacteria but not in others. In order to clarify the mechanism of development of such contamination, Streptomycin (SM) was administered to mice to induce changes in the prevalence of resistant E. coli. When this animal was added to the group, transfer to only one mouse was noted during a course of 13 days. This was considered to indicate the importance of the environmental factors including the enterobacterial flora for the development of transfer. To the group of mice in which SM was administered to decrease the normal enterobacterial flora, one mouse with a fixed presence of 0-6 strain E. coli (resistant to SM, TC and CP) was added. Transfer of the bacteria was noted slowly from the third day on. During the 30 day period, the transfer occurred to most of the mice, assuming the type of so-called chain intection followed by a subsequent disappearance. In the present study, attempts were made to clarify the process of re-uptake of the excreted E. coli into the animal, or the mode of contamination among individual animals through an experimental epidemiologic approach, thereby establishing the position of E. coli as a possible index of fecal contamination.
- 日本民族衛生学会の論文