[Enteric bacteria in children from two isolated institutions; with special reference to the variation in colicin types of Escherichia coli and in serotypes of Clostridium welchii].

The present study was designed to perform a long term observation on the bacterial excretion in human feces with special reference to Escherichia coli and Clostridium welchii. Fourteen children and 6 adult employees were chosen from 2 isolated institutions where mentally retarded child inmates were dwelling. One institution (K) has had several epidemics of dysentery in the past 5 years, whereas dysentery has never been reported in the other institution (T). Feces were quantitatively cultivated for bacterial counts. Variation in bacterial counts, change in serotype of Clostridium welchii, and change in excretion of chloramphenicol-resistant or colicin-producing Escherichia coli were individually examined during the 10 month period. 1. No significant difference was observed between the 2 institutions in regard to the bacterial counts of Escherichia coli, Clostridium welchii and the Enterococcus group. Only the Lactobacillus counts (mainly casei) differed between the two, which probably could be attributed to the fact that inmates in Institution T had been drinking milk containing Lactobacillus casei (100ml of approximately 108 cells/ml) daily. The antagonistic effect of the Lactobacillus from milk was not however evident against Escherichia coli, Clostridium welchii and the Enterococcus group. 2. Observations on individual variation in bacterial counts revealed that adults had the higher and the more stable Escherichia coli and Enterococcus counts in comparison to those in children. 3. Individual excretion state of the heat resistant Clostridium welchii was very unstable as indicated by frequent changes in the Hobbs serotype. 4. In contrast to Clostridium welchii, the excretion state of chloramphenicol-resistant Escherichia coli was individually characteristic, more long term carriers being seen in adults than in children. 5. Both resident and transient types of Escherichia coli were detected individually as indicated by colicin typing. Organisms having the same colicin type excreted at different times by the same person showed a similar O-antigenicity. These results imply that colicin typing is an effective method for investigation into Escherichia coli as is found in intestinal flora.