Researchers trying to mix S. aureus antibody cocktail

With increasing resistance to antibiotics, researchers are trying to devise a new weapon against a troublesome nosocomial pathogen -- Staphylococcus aureus.

Initial research is targeting the creation of a hyper-immune globulin that could be administered to high-risk patients upon hospital admission, conferring immunity should they become exposed to S. aureus. The project is the result of a breakthrough at Human Genome Sciences of Rockville, MD, where researchers recently announced they have identified more than 99% of the genome of S. aureus.1 That opens the door for the creation of "antibody cocktails" since it is now possible to identify and target the molecular components of the bacteria. Researchers at MedImmune in Gaithersburg, MD, will use the information to try and develop the antibody products, which would then be tested in animals and ultimately clinical trials.

Infecting an estimated 8 million people annually in the United States, the bacteria is a frequent cause of hospital-acquired infections -- particularly in its methicillin-resistant strains. In addition, the Centers for Disease Control and Prevention in Atlanta has warned of the possible emergence of vancomycin-resistant S. aureus, a pathogen that could be impervious to current antibiotics.

"Staph aureus is one of the targets of our program because of the issue of antibiotic resistance -- including the impending possibility of vancomycin resistance," says James F. Young, PhD, senior vice president for research and development at MedImmune. "We wanted to come up with a strategy that allowed us to attack the issue from a different direction -- that is using antibodies. There doesn't appear to be any correlation between the development of antibiotic resistance and the concurrent development of resistance to antibody."

Plans call for using the sequencing of the full DNA to identify proteins that would be targeted for "antibody mediated killing," he tells Hospital Infection Control. Those proteins would be used to generate antibodies that would be administered to hospital patients at risk for staph infections, such as those with indwelling catheters, he adds. At present, there are no vaccines or antibody products licensed to prevent or treat S. aureus, though the company has developed a similar product for respiratory syncytial virus.2

References

1. McCarthy M. Staphylococcal genome sequenced. Lancet 1996; 347:251.

2. Grothuis JR, Simores EA, Levin MJ, et al. Prophylactic administration of respiratory syncytial virus immune globulin to high-risk infants and young children. N Engl J Med 1993; 329:1,524-1,530. *