Scientists have figured out the mystery behind an organism that kills millions each year, and successfully completed a genetic map of a virulent strain of the bacterium that causes pneumonia and meningitis. This is an important step toward creating a vaccine to beat the bug. Scientists at The Institute for Genomic Research (TIGR) in Rockville, Maryland, said they had sequenced the complete genome of a very infectious strain of Streptococcus pneumoniae, or pneumococcus, after five years of work.

The researchers figured out that the bacterium, taken from the blood of a 30-year-old male patient in Norway, contained 2,236 different genes, including some that explained why it has been such a formidable menace. The microbe lives in the throat and back of the nose, and is present in up to 40 percent of people at any given time, said TIGR's Herve Tettelin, principle investigator in the research appearing in the journal Science. "We don't really know what prompts it to go into the pathogenic behavior,'' Tettelin said in an interview.

The organism migrates from the throat and nose to invade the lungs, blood and brain, preying on children and the elderly, killing millions by causing pneumonia, an inflammation of the lungs; meningitis, an infection triggering inflammation of the membranes covering the brain and spinal cord; and bloodstream infections. It also causes ear infections. "It's come back on the forefront of medical research now because it's tending to acquire antibiotic resistance, which is critical,'' Tettelin said. "Usually in the old days, you could clear it with a little bit of penicillin. Nowadays more and more strains appear to he resistant to it. So you need to tackle it in different ways.''

"Sometimes you can't clear it and so the infected patient dies without you being able to do anything. So what we need is to find new drug targets or vaccine candidates,'' he said. Tettelin said that knowing the bug's genetic secrets, and therefore its vulnerabilities, will help these efforts.

The researchers found that pneumococcus has qualities that help it invade the body's tissues. It is adept at shifting its genes, which could allow it to thwart counterattacks by the body's immune system.

About 92 different strains of this particular bug infect people. The researchers compared the virulent strain they sequenced to a benign laboratory strain and a second less-virulent strain. The TIGR team's strain contained 10 percent more genes than the others, indicating that those genes may be involved in the infectious process.

The researchers think a potential target for a vaccine or drugs could be genes that relate to certain enzymes the organism uses to break down the carbohydrates that bind together biological membranes. These enzymes help it maneuver through the body's defenses against invasion, as well as providing sugars for it to consume. " It's able to eat 14 sugars, which is a lot more than any other bug we've seen so far,'' Tettelin said.

The microbe has special traits that make it hard to beat. The study found that it might be better than most at performing the genetic changes that lead to resistance to medicine. In the past decade alone, it has acquired impressive resistance to antibiotics including penicillin. None of the vaccines now available can protect against all of its virulent strains.

Donald Morrison, a University of Illinois at Chicago biologist who assisted in the work, characterized the effort as ''a race to discover better ways to treat it before it discovers better ways to get around current treatments.''

From Reutershealth.com