title: Bacterial phenotype variants in group B streptococcal toxic shock syndrome.
abstract: We conducted genetic and functional analyses of isolates from a patient with group B streptococcal (GBS) necrotizing fasciitis and toxic shock syndrome. Tissue cultures simultaneously showed colonies with high hemolysis (HH) and low hemolysis (LH). Conversely, the HH and LH variants exhibited low capsule (LC) and high capsule (HC) expression, respectively. Molecular analysis demonstrated that the 2 GBS variants were of the same clonal origin. Genetic analysis found a 3-bp deletion in the covR gene of the HH/LC variant. Functionally, this isolate was associated with an increased growth rate in vitro and with higher interleukin-8 induction. However, in whole blood, opsonophagocytic and intracellular killing assays, the LH/HC phenotype demonstrated higher resistance to host phagocytic killing. In a murine model, LH/HC resulted in higher levels of bacteremia and increased host mortality rate. These findings demonstrate differences in GBS isolates of the same clonal origin but varying phenotypes.
authors.affiliation: Karolinska Institutet, Stockholm, Sweden. sendi-pa@magnet.ch
authors.forename: Parham
authors.initials: P
authors.lastname: Sendi
authors.forename: Linda
authors.initials: L
authors.lastname: Johansson
authors.forename: Samira
authors.initials: S
authors.lastname: Dahesh
authors.forename: Nina M
authors.initials: NM
authors.lastname: Van-Sorge
authors.forename: Jessica
authors.initials: J
authors.lastname: Darenberg
authors.forename: Mari
authors.initials: M
authors.lastname: Norgren
authors.forename: Jan
authors.initials: J
authors.lastname: Sjölin
authors.forename: Victor
authors.initials: V
authors.lastname: Nizet
authors.forename: Anna
authors.initials: A
authors.lastname: Norrby-Teglund
mesh_terms: D000818:Animals; D016667:Bacterial Capsules / Q000378:metabolism; D001426:Bacterial Proteins; D019115:Fasciitis, Necrotizing / Q000276:immunology / Q000382:microbiology / Q000503:physiopathology; D014644:Genetic Variation; D006461:Hemolysis; D006801:Humans; D008297:Male; D051379:Mice; D008875:Middle Aged; D009504:Neutrophils / Q000276:immunology; D009895:Opsonin Proteins / Q000378:metabolism; D010587:Phagocytosis; D010641:Phenotype; D012097:Repressor Proteins; D012772:Shock, Septic / Q000276:immunology / Q000382:microbiology / Q000503:physiopathology; D013290:Streptococcal Infections / Q000276:immunology / Q000382:microbiology / Q000503:physiopathology; D013292:Streptococcus agalactiae / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*
chemical_list: D001426:Bacterial Proteins; C432143:CsrR protein, Streptococcus pyogenes; D009895:Opsonin Proteins; D012097:Repressor Proteins