In order to evaluate the index organisms in fecal contamination of food, isolation and analysis of coliforms and
Escherichia coli distributed in 191 samples of foods (meats: 53, vegetables: 138) and 47 samples of environmental material (river water: 25, soil: 22) were carried out. The results were as follows. 1) Isolation frequencies of coliforms, fecal coliforms and enteropathogenic
E. coli from food were 92, 49 and 0%, respectively, in the case of meat, and 68, 28 and 0%, respectively, in the case of vegetables. Two hundred and six strains of isolated coliforms were identified in more than 16 species. The dominant species were
Citrobacter freundii, E. coli, Klebsiella pneumoniae, Klebsiella oxytoca and
Enterobacter cloacae amongthe coliforms, and
E. coli among the fecal coliforms. Isolation frequencies of
E. coli, C. freundii, K. pneumoniae, K. oxytoca and
E. cloacae from food were 49, 36, 19, 13 and 17%, respectively, in the case of meat, and 29, 20, 17, 15 and 7%, respectively, in the case of vegetables. The majority of the coliform species, other than
E. coli, failed to grow at 44.5°C, but did at 7°C. 2) Cold-adapted coliforms were detected at a frequency of 88% from river water and 73% from soil. The majority of cold-adapted coliforms isolated were identified as
K. pneumoniae, K. oxytoca and
C. freundii which failed to grow at 44.5°C. Isolation frequencies of cold-adapted
C. freundii, K. pneumoniae and
K. oxytoca were 12, 28 and 68%, respectively, in the case of river water, and 45, 0 and 32%, respectively, in the case of soil.
These results suggest that most of the coliforms distributed in meats and vegetables are cold-adapted
K. pneumoniae, K. oxytoca and
C. feundii which are also found in the environment.
View full abstract