Protection against endocarditis due to Staphylococcus epidermidis by immunization with capsular polysaccharide/adhesin.
BACKGROUND
Staphylococcus epidermidis is the principal pathogen in prosthetic valve endocarditis. The capsular polysaccharide adhesin (PS/A) has been shown to mediate attachment of bacteria to medical devices. In this study, we investigated the efficacy of active and passive immunization against PS/A in preventing S. epidermidis endocarditis in a rabbit model.


RESULTS
Aortic valve vegetations were produced by inserting a Teflon catheter into the left ventricle through the right carotid artery. Bacteremia and endocarditis were then established by implanting in the left jugular vein a catheter that was attached to an osmotic pump and contaminated with S. epidermidis strain RP62A. During a 3-week study period, of 64 blood cultures taken every second or third day from six nonimmune rabbits, 54 (84%) yielded strain RP62A. In rabbits actively immunized with PS/A, eight of 60 blood cultures (13%) were positive (odds ratio 5.0, 95% CI, 2.0-12.3, p = 0.005). At death, all six nonimmune rabbits had infected vegetations that yielded 10(6)-10(11) colony-forming units (cfu)/g of vegetation, whereas only one PS/A-immunized rabbit had an infected vegetation. Immunization protocols designed to elicit antibody to teichoic acid but not to PS/A afforded no protection against bacteremia or endocarditis. Infusion of monoclonal antibody to PS/A through a catheter in the right jugular vein provided a level of protection against both bacteremia and endocarditis comparable to that produced by active immunization. In vitro, antibody against PS/A was opsonic for S. epidermidis.


CONCLUSIONS
Immunoprophylaxis targeted at staphylococcal PS/A is a promising new approach to the prevention of prosthetic valve endocarditis.
Takeda
S
S
Channing Laboratory, Department of Medicine, Brigham and Women's Hospital.
Pier
G B
GB
Kojima
Y
Y
Tojo
M
M
Muller
E
E
Tosteson
T
T
Goldmann
D A
DA
D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D001422:Bacterial Adhesion; D003030:Coagulase / Q000032:analysis; D004697:Endocarditis, Bacterial / Q000517:prevention & control*; D007114:Immunization; D010587:Phagocytosis; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D011817:Rabbits; D018805:Sepsis / Q000517:prevention & control; D013203:Staphylococcal Infections / Q000517:prevention & control*; D013212:Staphylococcus epidermidis / Q000276:immunology*
D000911:Antibodies, Monoclonal; D003030:Coagulase; D011135:Polysaccharides, Bacterial