First Vaccine for Staphylococcus aureus

The study was published in the February 14, 2002, issue of The New England Journal of Medicine.

S aureus is a major cause of infection and death among hospital patients and a common cause of bacteremia, particularly in hemodialysis patients. Many strains are resistant to methicillin, the standard treatment, and some are even resistant to vancomycin, the only antibiotic known to kill methicillin-resistant S aureus.

The vaccine was developed by scientists at the US National Institute of Child Health and Human Development (NICHD) and Nabi (Boca Raton, FL, USA), a biotechnology company. They knew that two polysaccharides shielded S aureus, preventing the white blood cells of the immune system from recognizing them and making antibodies against them. So the researchers chemically coupled the polysaccharides to a protein to form a conjugate. This approach allowed the immune system to produce antibodies that could inactivate the bacteria. In a trial where patients were given either the vaccine or placebo, the vaccine reduced the occurrence of bacteremia by 57%, with 11 cases in the vaccinated group of 892 patients, and 26 cases in the control group of 906 patients. After the 40th week, the 57% fell to 26%, as antibody levels declined rapidly in dialysis patients.

Efforts to increase the efficacy of the vaccine include studies of a booster dose. In addition, researchers plan to target the vaccine to a newly discovered polysaccharide type 336 that they think will allow the immune systems of vaccinated patients to recognize nearly 100% of S aureus types found in blood infections.

"The conjugate vaccines were effective in hemodialysis patients who had severely depressed immunity,” noted John Robbins, M.D., chief of the NICHD's Laboratory of Developmental and Molecular Immunity and one of the study's authors. "It is likely that the vaccine will be more effective in individuals with less-depressed immune systems.”




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