Novel Observation of Hot-Cold-Hot Hemolysis Exhibited by Group B Streptococci

摘要

Six human isolates of group B streptococci (GBS) were cultured on blood agar anaerobically at 37°C for 18 h and then at 4°C for 6 h and reincubated anaerobically at 37°C for 6 h. Three of the strains showed a marked enlargement of the hemolysis zone compared with that obtained after hot-only (37°C for 18 h) or hot-cold (37°C for 18 h and then 4°C for 6 h) treatment. Subsequent broth culture experiments revealed that enhanced hemolytic activity due to hot-cold-hot treatment was observed in all 6 GBS strains when cultured in the presence of starch.