In a study of the Kanagawa phenomenon of Vibrio parahaemolyticus, both Kanagawa-positive and-negative strains were found to produce hemolytic factors that could not be differentiated on Wagatsuma blood agar. The presence of fermentable carbohydrates in media containing high concentrations of NaCl promoted the growth of V. parahaemolyticus and resulted in a marked decrease in medium pH and increased hemolysin production. The Kanagawa hemolysis of test strains differed according to the carbohydrates added. Clearly defined Kanagawa hemolysis was observed in blood agars of high salt content, but the distinction was lost in media containing 3% NaCl. From the results of this study, the Kanagawa hemolysis was interpreted as an expression of quantitative difference in hemolysin production, a conclusion that is clearly demonstrated on special blood agar of high salt content.

A total of 949 strains of Salmonella typhi isolated in Korea from 1968 to 1975 were tested for drug resistance and distribution of R plasmids. Resistance was mostly restricted to streptomycin (SM) and sulfisomidine (SA), singly or in combination, at a low degree. A small number of strains (1.5%) were resistant to four or more drugs: chloramphenicol (CM), tetracycline (TC), SM, SA, ampicillin (AP), and kanamycin (KM). No strain was resistant to nalidixic acid or to a 1:20 mixture of trimethoprim and sulfamethoxazole. Nor was there any strain singly resistant to CM, TC, AP, or KM. Transfer experiments of multiple-drug resistance to Escherichia coli ML1410 showed that all the strains resistant to four or more drugs carried R plasmids, whereas those weakly resistant to three or less drugs did not. The quadruply resistant strains carried one R plasmid determining CM, TC, SM, and SA resistance, and sextuply resistant ones carried two plasmids, one determining CM, TC, SM, and SA resistance and the other determining AP and KM resistance. One strain carrying a plasmid determining AP and KM resistance was also found. The transfer frequency of CM, TC, SM, and SA resistance was much higher than that of AP and KM resistance. The resistance of S. typhi was more efficiently transferred to E. coli at 25°C than at 37°C.

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In a study of the effect of glycerin in transport media on Vibrio parahaemolyticus and Salmonella , it was found that a concentration of 30% glycerin was highly inhibitory for V. parahaemolyticus and to a lesser degree for Salmonella . The incorporation of peptone or human feces in media did not reduce the inhibitory effect of glycerin. In media with 15% glycerin, viable counts of V. parahaemolyticus and Salmonella increased after 24 hr of incubation both in the presence and absence of feces. Due to the concurrent increase in the total bacterial count in the media containing feces, no enrichment effect was noted.

Almost all strains of Vibrio parahaemolyticus produced Kanagawa-type hemolysis on media of high salt content in the presence of fermentable carbohydrates.