食品衛生に関する腸球菌の研究 : 第2報 日常食品の腸球菌附着状況
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概要
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For the purpose of evaluating the sanitary significance of enterococci as indices for fecal contamination, the author performed investigations on the pollution of foods with enterococci, coliform organisms and E. coli in 10 different kinds of foods (meat, potato salad, buckwheat noodle, puff cream, dried scad, Tapes Philippinarum, chlam, shucked clam, oyster and croquette) in which similar experiments had never been performed. Two hundred samples of these foods were examined for these organisms in summer and winter, and the most probable numbers of the organisms were determined by the method developed by the author. The method developed by the author makes it possible to examine the distribution of the three types of organisms using the same dilutions of food samples. Consequently, the result is free from the error that might be caused by the use of different dilutions. The results are summarized as follows: (1) Enterococci were detected in all samples of meat, potato salad, buckwheat noodle, dried scad, Tapes Philippinarum, shucked clam and oyster and in 18 out of the 20 samples (90 %) of puff cream and clam. While all the samples examined in both seasons showed the presence of less than 10,000,000 the value of M. P. N. enterococci, some of the samples of meat, potato salad, buckwheat noodle, puff cream and dried scad examined in summer showed the presence of more than 1,000,000 enterococci. The samples of dried scad gave the highest average number in summer, followed by those of puff cream, meat, potato salad, buckwheat noodle, clam, Tapes Philippinarum, shucked clam and croquette in the indicated order, while the samples of meat gave the highest average number in winter, followed by those of oyster, potato salad, puff cream, dried scad, shucked clam, Tapes .Philippinarum, clam and buckwheat noodle in the indicated order. (2) In all the samples of meat, potato salad, buckwheat noodle, puff cream and dried scad, the numbers of enterococci detected were higher in summer than in winter. No appreciable difference in number was noticed between the samples of Tapes Philippinarum, clam and shucked clam examined in summer and winter. (3) Many samples were found positive for enterococci, just as they were found positive for coliform organisms. Samples of puff cream and croquette positive for enterococci were larger in number than those positive for coliform organisms. The average numbers of enterococci found in the samples of clam and croquette examined in summer and in those of puff cream and dried scad examined in winter were higher than the average numbers of coliform organisms found in the same samples. A marked correlation between the numbers of the two types of organisms was found in samples of buckwheat noodle and puff cream examined in summer and in those of clam examined in winter. In many samples of foods, the ratio M. P. N. of enterococci/M. P. N. of coliform organisms varied with the seasons examined. (4) The samples of foods found positive for enterococci were far larger in number than those found positive for E. coli, and the values of M. P. N. of enterococci was generally larger than those of E. coli. The samples of puff cream examined in summer showed a marked correlation between the values of M. P. N. of these two organisms.
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