An epidemic of aseptic meningitis occurred in Hokkaido from July to September 1965.
At the beginning of the epidemic seven strains of ECHO 6 virus were recovered from patient stool.
Then assuming the virus as the causative agent, virological and serological investigation was performed by the author on 17 stool specimens and 21 paired sera collected at Ebetsu Municipal Hospital in Hokkaido.
For serological diagnosis, author adopted three reactions: neutralization (Neut) test, complementfixation (CF) test and hemagglutinin-inhibition (HI) test.
And seven isolated strains and three prototype strains (ECHO 6, 6, 6) were tested on its antigenity. Out of them, only one isolated strain (HE 39) was found to have hemagglutinin and (CF) antigen of high value, so that this strain was adopted as an antigen for further serological survey.
Excluding three cases which were apparently thought not to be infected with ECHO 6 virus, serological tests were performed on remaining 18 cases.
The tests showing positive reaction and the number of cases were as follows:
Positive (Neut)(CF)(HI) in 4 cases; positive (Neut)(HI) in 4 cases; positive (CF)(HI) in 1 case; positive (HI) alone in 5 cases; positive (CF) alone in 1 case.
Neither positive (Neut) alone nor combination of positive (Neut) and (CF) were encountered.
These results led the author to the conclusion that the combination of (HI) and (CF) was sufficient for serological diagnosis of ECHO 6 infection, neutralization test being not indispensable.

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Sixty six strains of Salmonella bacilli were recovered at this hospital from 1960 to 1964. They were divided into 16 types, including Salmonella paratyphi A, S. paratypin B, S. derby, S. typhi murium, S. tompson, S. potsdam, S. narashino, S. nagoya, S. newport, S. typhi, S. enteritidis, S. pullorum, S. give, S. newington, S. senftneberg, and S. klefeld.
Out of these strains S. derby, S. give, S. newington and S. klefeld were recovered for the first time in this hospital.
Sensitivity test against streptomycin (SM), Chloromycetin (CM), Tetracyclin (TC) and Sulfonamide (SA) was performed on 40 strains. Degree of resistance to these antibiotics remained bellw 100 mg/ml with one exceptional strain of S. give, that showed 100 mcg/ml resistance level against (SM). Sensitivity level to (SA) remained lower than 100 mcg/ml in all strains without exception.
Eight cases out of repeatedly investigated 20 cases discharged drug-resistant strains in the course of disease. Out of them, one strains of S. give was proved, as mentioned above, to be resistant to (SM) alone.
When one stool specimen was cultured on such different media as antibiotics containing medium (A) and usual SS agar (B), both strains obtained on (A) and (B) were proved coincidentally drug-resistant very often.
It was also not so infrequent that the strains on (B) were drugsensitive on the one hand and those on (A) demonstrated drug-resistance on the other.
The strains once proved resistant in the course of disease mostly remained resistant successively. It was demonstrated that in a few cases, however, once acquired drugresistance was lost in the course of illness.
The great majority of the strains which showed increase in the drugresistance, acquired, at the same time, the multiple resistance to several drugs, though it did not always coincide with the pattern and amount of drugs used.

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