The effects of yoghurt on fecal flora and fecal putrefactive products were studied in eight healthy male volunteers (aged, 38-59 years) who consumed 500 g of yoghurt once a day for 2 weeks. The yoghurt was prepared with Lactobacillus delbrueckii subsp. bulgaricus strain 2038 and Streptococcus salivarius subsp. thermophilus strain 1131. On day 14 of yoghurt consumption, Clostridium and Lactobacillus tended to decrease in number, while bifidobacteria significantly increase (p<0.05) in 5/8 volunteers who used to have a small number of bifidobacteria in the intestines. No detectable changes occurred in the level or the incidence of other organisms. The fecal pH values did not change remarkably during yoghurt consumption. Such putrefactive products as ammonia and indole in the stools decreased significantly (p<0.05) during yoghurt consumption. No significant changes were shown in the hemogram throughout the experimental period.
Synthetic oligonucleotide primers were used in the polymerase chain reaction (PCR) technique to detect the gene encoding Clostridium perfringens type A enterotoxin (CPE). Sequences of the primers are 5'-ATCCTTGATTTAGCTGCTGC-3' and 5'-ACAAGAACATATTGTCCGGC-3', which are constructed to amplify a 302-base-pair (bp) region of the CPE gene. All CPE-producing C. perfringens strains tested, such as C. perfringens NCTC8239, gave an amplified DNA fragment, while non-CPE producing C. perfringens strains gave no amplification. The amplified DNA fragment was recognized at a molecular size of about 360-bp on polyacrylamide gel electrophoresis (PAGE) at room temperature, but migrated about 302-bp on PAGE at 53°C. Each cleavage pattern of the amplified DNA with four restriction endonucleases, Dde I, Hinf I, Mbo I, and Hind III, was consistent with the patterns expected from the published sequence of the CPE gene. In outbreaks, the enterotoxigenicity of C. perfringens isolates from patients, food handlers, or incriminated foods could rapidly be judged by the PCR method, the results of which were consistent with those of the culture and the immunological method. Thus, these results show that the PCR method provides a simple and rapid tool for the detection of the potentially enterotoxigenic C. perfringens, and furthermore, suggest that CPE is not a common structural component of the C. perfringens spore coat.