Researchers at Umeå University, Sweden, and Michigan State University, USA, have discovered a type of molecule that can kill chlamydia bacteria but spare bacteria that are important for health. The discovery opens the door for further research towards developing new antibiotics against chlamydia, the world's most common bacterial sexually transmitted disease with 130 million cases a year.

"No one should have to live with chlamydia. But the problem is that the treatments we have today do not distinguish between dangerous and friendly bacteria. A growing problem is also that more and more bacteria are becoming resistant to today's broad-acting antibiotics," says the study's lead author Barbara Sixt, associate professor at the Department of Molecular Biology at Umeå University, Sweden.

The bacterium that causes chlamydia, Chlamydia trachomatis, has very special properties. Just like viruses, it invades cells in the human body, which it then reshapes so that they give the bacterium a home where it can grow and multiply.

"We thought it could be possible to find a way to outsmart the bacterium's lifestyle by interfering with its special properties and its interactions with human cells," says the study's first author Magnus Ölander, former postdoc at Umeå University.

The researchers searched through large collections of chemical molecules to find molecules that can eradicate the growth of the chlamydia bacterium in human cells in laboratory cultures. More than 60 possible anti-chlamydia molecules were identified. It was a matter of finding molecules that could selectively kill the chlamydia bacterium but at the same time be harmless to human cells and to beneficial bacteria that the body needs to stay healthy. After further refined studies, the researchers were able to identify a particularly potent molecule.
The molecule in question was found to be able to inhibit the bacterium's ability to produce fatty acids, which are necessary for its growth.

"There is still a long way to go before we have a new treatment, but this finding may prove very important in developing new antibiotics that are both effective but at the same time gentle on the body”, says Barbara Sixt.

The research was carried out in collaboration with André Mateus and Björn Schröder at Umeå University, Sweden, and Jeremy Lohman at Michigan State University, United States of America.
Chlamydia often causes mild symptoms but if left untreated can cause long-term damage to the reproductive organs, especially in women. This can cause chronic pain and infertility and can have consequences for pregnancy and childbirth. Chlamydia may also contribute to the onset of cancer of the cervix and ovaries. Every year, about 25,000 people in Sweden are diagnosed with chlamydia, 130 million worldwide.

The study is published in the scientific journal PLoS Biology.