Acne bacteria genome decoded

European scientists have sequenced the complete genome of a bacterial species involved in many cases of acne, and they're already working on potential new treatments based on that achievement.

"We have identified this target, and we want to see if we can block its enzymes that degrade tissues, and also block enzymes that interact with the immune system," said Holger Bru"ggemann, lead author of a report on the sequencing in the July 30 issue of Science. He took part in the research at the Georg-August University in Go"ttingen, Germany, and now is a postdoctoral fellow at the Pasteur Institute in Paris.

Common inhabitant of the skin

The bacterium, Propionibacterium acnes, is a common inhabitant of human skin. It usually lives in the glands that secrete oil into hair follicles. The activity of its enzymes on the oil is believed to produce substances that can trigger acne. Other factors are involved, however, including hormones.

P. acnes has also been linked to a number of other medical problems, including ulcers of the cornea, gallstone formation and endocarditis, or damage to heart tissue.

P. acnes has "quite a small genome," said Bru"ggemann, with only 2 333 genes compared to the 4 000 of E. coli, a common bacterium. But some of those genes code for "host-degrading enzymes," and others interact with the immune system in a way that can lead to the pimply outbreaks of acne, he said.

A more targeted treatment needed

Dermatologists would welcome a more targeted treatment of acne, Bru"ggemann said. "Nowadays if you have acne you get treated with antibiotics, which have side effects," he said. "We don't want to kill all the bacteria, only the ones that cause acne."

A new treatment would be helpful because "patients are increasingly concerned about antibiotics," said Dr Susan Goodlerner, a spokeswoman for the American Academy of Dermatology.

That concern has led to increasing use of phototherapy, a blue-light treatment, Goodlerner said. But treatment usually starts with topical antibiotic treatment, a salve spread on the skin.

Topical antibiotics help most patients, but "some people seem to be resistant to antibiotics," Goodlerner said. Phototherapy is the next step for such patients.

The last resort

As a last resort, if antibiotics and phototherapy fail, the dermatologist can use Roaccutane (isotretinoin), "which works in the most severe acne," she said.

But Roccutane is known to cause birth defects, including brain and heart damage and cleft lip and palate. The US Food and Drug Administration instituted a voluntary testing and contraceptive programme for women considering Roaccutane, but a statement by the March of Dimes Birth Defects Foundation in February said major birth defects caused by exposure to Roaccutane and other brands of isotretinoin...continue to occur in the United States.