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Group B streptococcal C protein-associated antigens: association with neonatal sepsis

C S Chun1, L J Brady, M D Boyle

  • 1Department of Pediatrics, University of Florida, Gainesville.

The Journal of Infectious Diseases
|April 1, 1991
PubMed

Insights

The gamma antigen in group B streptococci (GBS) may be a virulence factor in early-onset sepsis. Most type III GBS strains express the c protein, but only the gamma antigen showed increased association with pathogenic strains.

Area of Science:

  • Microbiology
  • Immunology
  • Neonatal infectious diseases

Background:

  • Group B Streptococcus (GBS) is a leading cause of neonatal sepsis.
  • The GBS c protein (Ibc) is linked to several antigens (alpha, beta, gamma, delta).
  • The role of these antigens in GBS virulence is not fully understood.

Purpose of the Study:

  • To evaluate the virulence potential of GBS c protein-associated antigens.
  • To investigate the association of these antigens with GBS pathogenicity in neonates.

Main Methods:

  • Serotyping of 255 GBS isolates from septic neonates, healthy neonates, and pregnant women.
  • Radioimmunoassay using intact bacteria to detect GBS antigens.
  • Survey for reactivity with sera to c protein and its associated antigens.

Main Results:

  • Most (66%) type III GBS strains expressed the c protein, contrary to previous findings.
  • The gamma antigen was significantly associated with early-onset GBS sepsis strains (P = .007).
  • This association was independent of type-specific polysaccharide antigens.

Conclusions:

  • The gamma antigen may serve as a potential virulence factor in GBS causing early-onset sepsis.
  • Other c protein-associated antigens (alpha, beta, delta) did not show independent association with pathogenic strains.

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