Distribution of Edwardsiella tarda and Hydrogen Sulfide-producing Escherichia coli in Healthy Persons

Abstract

During the period from January through December in 1973, the survey centering on the detection of Salmonella and Shigella was performed on the fecal specimens of 255, 896 healthy school children and 97, 704 food handlers in Tokyo. On the course of this survey, 92 strains which were presumed as Edwardsiella tarda by preliminary tests for identification using TSI agar and LIM (Lysine-Indole-Motility) medium were isolated. Further biochemical tests of these isolates were conducted for final identification of their species. As a result, out of 92 isolates, 26 were identified as E. tarda and the remaining 66 as hydrogen sulfide (H₂S)-producing Escherichia coli.
Among many biochemical tests, salt tolerance test can be defined to be a very useful criterion for the differentiation between two species, for E. tarda could only grow in peptone water containing less than 3% sodium chloride, while H₂S-producing E.coli, could even grow in peptone water containing 7% sodium chloride.
In the light of the isolation frequency that E. tarda was obtained from only one food handler (0.001%) and 25 school children (0.01%), and H2S-producing E. coli was from 9 food handlers (0.01%) and 57 school children (0.02%), it is suggested that both H₂S-producing E. coli and E. tarda are distributed more widely in children than in adults. Isolation of E. tarda and H2S-producing E. coli showed such seasonal variations that they could be isolated in a period from April through November with a peak in August, but not through December to March.
Of 26 strains of E. tarda, only one was proved to be resistant against more than 100μg/m1 of SM. On, the other hand, 41 strains out of 66 H₂S-producing E. coli were single or multiple resistant against antibioticsexamined.