A total of 1, 019 samples of milk, meat and fish and their products were examined for the incidence of Staphylococcus aureus and the production of staphylococcal enterotoxin from strains isolated between 1995 and 1998 in China. Overall, 381 samples (37.4%) were contaminated with S. aureus. The rate of isolation was 46.7% for raw milk, 6.3% for dairy products, 73.6% for chicken meat, 29.5% for pork, 25.0% for beef, 19.5% for meat products and 30.9% for fish and shellfish. None of S. aureus was found in yoghurt and dry milk. Fortyeight (33.1%) of the 145 isolates from milk and dairy products, 61 (29.5%) of 207 isolates from meat and meat products, and 6 (20.7%) of 29 isolates from fish and shellfish produced staphylococcal enterotoxin, types A to E, respectively. The most predominant type was C, followed by A and B.
Effects of frozen yoghurt independently or in combination with lactosucrose consumption on fecal microbiota and fecal putrefactive products were studied in nine healthy male volunteers (21-24 years of age) who consumed 60 g of frozen yoghurt (FY) /day for 2 wk followed by 60 g of FY in combination with 2 g lactosucrose (FY-LS) /day for 2 consecutive wk. The yoghurt was prepared with cultures of Lactobacillus helveticus, L. acidophilus, Bifidobacterium bifidum, and Streptococcus thermophilus. After 2wk of FY consumption, the levels of bifidobacteria were increased and the levels of lecithinase negative clostridia decreased significantly (p<0.05) compared with the levels before consumption, respectively. Fecal concentrations of ammonia, sulphide and indole (p<0.01), and phenol and cresol (p<0.05) were decreased significantly after 2wk of FY consumption compared with the levels before consumption. The amounts of lactic acid and acetic acids were significantly increased (p<0.05) during FY consumption. The levels of bifidobacteria were significantly higher (p<0.01) during FY-LS consumption than those during FY consumption, while the levels of lecithinase negative clostridia, and the levels and the frequency of occurrence of clostridia including Clostridium perfringens were significantly lower (p<0.05) after 2 wk of FY-LS consumption than those of FY consumption. Fecal concentrations of ammonia, sulphide, phenol, cresol, indole and skatol were significantly lower (p<0.05) during FY-LS consumption than those of FY consumption. Lactic acid and acetic acids were significantly higher (p<0.05) during FY-LS consumption than those of FY consumption. Fecal pH values and water contents were slightly lower and higher during FY-LS consumption than those of FY consumption compared with the values before consumption, respectively. Fecal weights were significantly increased (p<0.05) during FY-LS consumption than those of FY consumption.
In a method practiced for the detection of Salmonella on chicken meat in one day, we used a Bactometer together with pre-enrichment broths and a Salmonella Rapid Latex Test. Three growth media used as pre-enrichment broths and the incubatory temperature were compared using the Bactometer. Impedance-Splitting Salmonella broth (BS) as a growth medium and the detection of Salmonella in chicken meat using a Bactometer were investigated in this study. 1. Salmonella on chicken meat in one day could be detected using a Bactometer and the Rapid Latex Test at the same time. 2. A Bactometer and the Rapid Latex Test are used together with ISS 37°C incubation for the detection of Salmonella after 8 h culture at 43°C in SBG (Selenite Billiant Green) medium.
Lactic acid bacteria belonging to the human normal flora of the mouth and intestine were used for fermented food as starter cultures. In salted vegetables fermented by lactic acid bacteria, the fermentation of lactic acid bacteria was markedly affected by salt concentration. A sample of 23 salted vegetables were purchased from a retail shop in Tokyo, and 2 homemade samples were also used. A total of 164 strains of lactic acid bacteria were isolated from 19 samples. For the fermentation test, API 50 CH galley and CHL medium were used according to the manufacture's instructions, and identification of species of lactic acid bacteria was performed using API 50 kit and Bergey's manual. Lactic acid bacteria levels ranged between 104 cfu/g and 108 cfu/g widely. The isolated lactic acid bacteria were Lactobacillus, Lactococcus, Leuconostoc and Pediococcus. The predominant species were Leuconostoc mesenteroides and Lactococcus lactis.