Scientists have cracked the genetic code of a bacterium involved in acne, an advance they say could lead to new treatments.
The bacterium's genes may explain how it causes acne
The German team from Georg-August University in Gottingen found genes that help the bacterium attack and destroy components of human skin.
Others were involved in triggering inflammation.
Knowing how the bacterium causes acne could offer new avenues of drug research, say the authors in Science.
The common skin problem affects up to 80% of young adults, but can affect older people too.
It usually starts in puberty when skin glands produce excess grease. Dead skin cells and grease block pores on the face, upper arms, upper back, and chest.
Researchers have known that the normally harmless bacterium Propionibacterium acnes, which is found on all adult skin, is implicated in acne.
This bacterium lives in the glands that secrete oil into hair follicles.
The German team sequenced the entire genome of the bacterium and identified 2,333 genes.
The function of many of these genes explained how the bacterium might trigger acne. Many were blueprints for enzymes that break down the skin.
Lead scientist Holger Bruggeman said: "We were astonished to see how many genes were involved in degrading the human tissue."
He said the bacterium lived off the products of this degradation.
"The next step is to find a therapy specifically against those enzyme systems."
He said it was unclear why some people were more prone to acne than others, but said it might be down to the immune system.
"When the bacterium degrades the human skin the inflammation kicks in. We think the immune system of each person is different."
He said the reason acne is common in adolescence might be because this is a time when the skin produces more oils, which the bacterium feeds off.
Alison Dudley, chief executive of the Acne Support Group, said: "It's a really exciting development for future generations.
"We know that having acne can lead to suicidal thoughts and depression.
"To have a major breakthrough is very welcome for the future but, in the meantime, follow the acne support two-month rule. Try a treatment for two months and if you see no improvement go back to your doctor and try something else.
"There's something that will work so don't despair," she said.