CAMP factor is not essential for systemic virulence of Group B Streptococcus

The Gram-positive pathogen Group B Streptococcus (GBS) is the leading cause of bacterial pneumonia, sepsis, and meningitis in human newborns. GBS elaborates a pore-forming toxin known as CAMP factor that synergizes with Staphylococcus aureus beta-toxin, generating a co-hemolytic reaction useful in identification of GBS in the clinical laboratory. To evaluate the indirect evidence implicating CAMP factor in GBS pathogenesis. the cfb gene encoding the pore-forming cytotoxin was deleted by precise allelic replacement. The Virulence properties of the CAMP factor mutant were then explored by a series of in vitro and in vivo assays. Compared to wild-type. the isogenic GBS Delta cfb mutant demonstrated equivalent phagocyte resistance and endothelial cell invasiveness and also retained full virulence in a mouse model of infection. Our data suggest that CAM P factor expressed in its native context is not essential for systemic virulence of GBS. (C) 2007 Elsevier Ltd, All rights reserved.