Enterococcus as an Indicator for Contamination

Abstract

1. The most probable numbers (MPN) of Escherichia coil and Enterococcus in feces were determined in 10 head each of 9 animal species, including man, by the A. Y. I.-E. A. C. broth method. E. coli was found in dog, man, sheep, Japanese native ox, chicken, goat, guinea pig, rabbit, and dairy cow in the decreasing order of MPN. Enterococcus was detected in dog, sheep, chicken, man, goat, rabbit, guinea pig, Japanese native oxen, and dairy cow in the same order as above.
2. The number of enterococci was about 1/20 to 1/10 that of E. coli organisms in all the animals, except the chicken, in which it was almost equal to the latter.
3. When 487 samples of food were examined, 20.5 per cent of them was positive for E. coil and 13.7 per cent for Enterococcus. The resultant difference was significant at 1 per cent of a when examined by the X²-test.
4. The isolated organisms were classified into Streptococcus faecium (41.0%), Str. faecalis (36.4%), Str. durans (5.36%), Str. faecalis var. liquefaciens (4.6%), and atypical strains (12.64%).
5. Str. faecium was mostly found among the strains isolated from feces and Str. faecalis among those isolated from food.
6. The differences between the two bacterial species in the numbers of organisms isolated from “soft cream” and fresh milk were not significant at 5 per cent of α when examined by t-distribution.
These results seem to indicate that detection of enterococci, -when performed at the same time with that of E. coli organisms, may be useful as additional means for the determination of the degree of food contamination.