Friday, May 28, 1999 Published at 15:01 GMT 16:01 UK
Superbug could be conquered
S. aureus: A common cause of hospital-acquired infections
A vaccine to protect people from one of the most problematic microbes in modern medicine is now a step closer.
US researchers have shown they can vaccinate against Staphylococcus aureus - in mice at least.
About 500,000 patients in America contract a Staphylococcus infection when they go into hospital for treatment. In particular, S. aureus is now causing serious problems because it is developing resistance to some of our best antibiotics.
There are even some strains of this bacterium that can partially side-step vancomycin, which is regarded as the "last resort" antibiotic treatment.
S. aureus causes illnesses that range from minor skin infections and abscesses to life-threatening diseases such as severe pneumonia, meningitis, bone and joint infections, and infections of the heart and bloodstream.
Large numbers of antibodies
The research team, funded by the US National Institute of Allergy and Infectious Diseases (NIAID), identified a large sugar molecule that sits on the surface of the microbe known as PNSG (poly-N-succinyl Beta-1-6 glucosamine). It seems this molecule plays an important role in the process of infection.
The scientists purified PNSG and injected it into rabbits. This prompted their immune systems to produce large numbers of antibodies, the special proteins that fight infection.
These PNSG antibodies were then injected into mice, which were exposed to eight different strains of S. aureus, including strains resistant to the antibiotic methicillin and partially resistant to vancomycin.
None of the lab mice developed an infection. The scientists must now make it do the same in humans.
"Our findings suggest that this vaccine has the potential to provide immunity to the multi-drug resistant S. aureus 'superbug' that we have heard alarming reports of in the last year or so," says lead researcher Dr Gerald Pier.
He says the same molecule is produced in a number of different bacterial strains that cause problems in hospitals, suggesting that any future human vaccine could have very wide benefits.
Dr Pier adds that he and his colleagues hope to move the PNSG vaccine into human trials soon, but predicts that such trials are one to two years away.
The research is published in the journal Science.