DETERMINATION OF THE HEMOLYTIC ACTIVITY OF VIBRIO CHOLERAE
1971 Volume 24 Issue 2 Pages 83-91
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1971 Volume 24 Issue 2 Pages 83-91
There is no definite opinion on the reliability of the hemolysis test for differentiation between classical and El Tor biotypes of Vihrio cholerae, serotype 1, although several improved modifications of the test have been reported. In order to obtain consistent methods for determining hemolytic activity of V. cholerae, studies were carried out using 1, 222 strains of the vibrio. It was found, in a preliminary study, that peptone and extract produced from animal tissue stimulated hemolytic activity in culture and that heart infusion broth consisting of those two ingredients was one of the suitable basal media for the hemolysis test. No variation among several batches of dehydrated heart infusion broth of Difco products was observed.
Among plain heart infusion broth (HIB), heart infusion broth by Feeley and Pittman (FP-HIB), glycerolized heart infusion broth (HIGB) and glycerolized brain heart infusion broth, the largest number of hemolysispositive tubes were obtained with HIGB. The results given by two agar plates, an aerobic plate of brain heart-thioglycollate-cystine agar (BHTCA), devised by the authors during the course of this study, and an anaerobic plate of heart infusion agar with washed sheep red cells were also compared with those given by HIGB. It was demonstrated that BHTCA was also satisfactory for the hemolysis test of V. cholerae.
Thus, when 1, 124 strains resistant to polymyxin B and to Mukerjee's phage IV with one exception being sensitive to the latter were tested in HIGB and BHTCA, the hemolytic activity was demonstrated in 99% of the strains. Classical strains were consistently nonhemolytic in/on these media; no false positive was recognized in any of them.
However, some varying results were recognized between HIGB tube and BHTCA plate. Variation was also given even in the same medium among strains which revealed weakly or no hemolytic activity. From these results, in this paper the joint use of HIGB and BHTCA has been recommended for the determination of hemolytic activity of V. cholerae. The test should be repeated if a doubtful or negative result is obtained.
Role of glycerol in HIGB and of thioglycollate and cystine in BHTCA for detection of hemolytic activity was discussed.
