title: Transposon mutants of Staphylococcus epidermidis deficient in elaboration of capsular polysaccharide/adhesin and slime are avirulent in a rabbit model of endocarditis.
abstract: Virulence comparisons were made in a rabbit model of endocarditis between wild-type and transposon mutants of Staphylococcus epidermidis deficient in elaboration of the capsular polysaccharide/adhesin (PS/A) and slime. The parental phenotype grew from 36 (61%) of 59 cultures of blood. The PS/A-negative phenotype grew in 1 (1%) of 98 cultures of blood (P < .001). No animals infected with PS/A-negative strains developed endocarditis compared with 75% of rabbits infected with PS/A-positive strains. PS/A-producing strains survived better than did PS/A-deficient strains in intact, absorbed rabbit or human serum plus human leukocytes. There was also greater deposition of C3 onto the PS/A-deficient strains than with the PS/A-producing isogenic strains. PS/A functions as an antiphagocytic bacterial capsule preventing C3 deposition and phagocytosis; loss of this structure increases the strain's susceptibility to opsonic killing and decreases its virulence.
authors.affiliation: Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: H
authors.initials: H
authors.lastname: Shiro
authors.forename: E
authors.initials: E
authors.lastname: Muller
authors.forename: N
authors.initials: N
authors.lastname: Gutierrez
authors.forename: S
authors.initials: S
authors.lastname: Boisot
authors.forename: M
authors.initials: M
authors.lastname: Grout
authors.forename: T D
authors.initials: TD
authors.lastname: Tosteson
authors.forename: D
authors.initials: D
authors.lastname: Goldmann
authors.forename: G B
authors.initials: GB
authors.lastname: Pier
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001422:Bacterial Adhesion; D003167:Complement Activation; D004251:DNA Transposable Elements; D004696:Endocarditis / Q000276:immunology / Q000382:microbiology*; D006801:Humans; D016254:Mutagenesis, Insertional; D010641:Phenotype; D011135:Polysaccharides, Bacterial / Q000378:metabolism*; D011817:Rabbits; D013212:Staphylococcus epidermidis / Q000235:genetics* / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics
chemical_list: D004251:DNA Transposable Elements; D011135:Polysaccharides, Bacterial