A Study of Group B <I>Streptococcus</I> with Special Reference to the Relationship Between Serological Type and Virulence

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  • OGURO Hiroshi
    Department of Public Health, Toho University, School of Medicine

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  • B群溶血連鎖球菌の血清型と病原性に関する研究
  • Bグン ヨウケツ レンサ キュウキン ノ ケツセイガタ ト ビョウゲンセイ ニ
  • A Study of Group B Streptococcus with Special Reference to the Relationship Between Serological Type and Virulence

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Abstract

Type distribution of group B streptococci recently isolated in Japan from the infants with sepsis and/or meningitis has shown and for the purpose to investigate the relationship between serological type and virulence of strains, intracerebral challenge method has been applied.<BR>The results were as follows;<BR>Total of 127 strains of group B streptococci from the infants with sepsis and/or menigitis were identified from 1976 to 1982 in this laboratory. And 64.5% of them were type 111 or 111 R which had polysaccharide 111 and 29.1% were type 1a or 1c which had polysaccharide 1a. Case fatality rate of these disease with the strains having polysaccharide la was about 50%, showing significantly higher rate compared with the other type of strain.<BR>For the discussion of the virulence of group B streptococcus, mouse virulence test by intracerebral challenge method which is the reference method of a protection test for B. pertussis, has been applied. Group B streptococci grown in Todd Hewitt broth for 18 hours were centrifuged and resuspended in steriled physiological saline and 0.025 ml of serially diluted suspension were challenged to mouse intracerebrally. Death and illness were observed for seven days after the challenge. This method seems to be useful for the comparison of virulence of group B streptococci for the following reasons. 1) There were clear dose-response relationship between challenge dose and fatality of mouse. 2) There observed clear relationship between challenge dose and survival time. 3) It was observed difference in virulence among the serotypes of strains with reproducibility. 4) Passive immunization was successfully examined with hyperimmune serum by this method.<BR>It was confirmed polysaccharide 1a was important factor for virulence in the case of type 1a or 1c strains from the results by mouse intracerebral challenge method.

Journal

  • Kansenshogaku Zasshi

    Kansenshogaku Zasshi 58 (5), 376-384, 1984

    The Japanese Association for Infectious Diseases

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