New challenges for diagnosis of bacterial STIs

This year cases of sexually transmitted infections (STIs) have risen by 2% in the UK, in spite of a small drop in the incidence of syphilis and gonorrhoea, according to scientists speaking today (Wednesday 28 November 2007) at the Federation of Infection Societies Conference 2007 at the University of Cardiff, UK, which runs from 28-30 November 2007.

An outbreak of lymphogranuloma venereum has been detected following reports of the disease in Europe. “From October 2004 to the end of April 2007, 492 cases of lymphogranuloma venereum were diagnosed in the UK. These cases were predominantly in men who have sex with men and many of the patients were also infected with other STIs, particularly with HIV,” says Professor Catherine Ison from the Health Protection Agency Centre for Infections in London.

Until recently doctors saw very few cases of lymphogranuloma venereum in the UK, Europe and other developed countries. The disease is caused by certain strains of the bacterium Chlamydia trachomatis and required new diagnostic tests, that had previously not been available in the UK, before the outbreak could be detected.

Bacteria evolve all the time, and the new sexually transmitted bacterial diseases including this new variant of Chlamydia trachomatis are presenting fresh challenges in diagnosis to medical support teams.

“Microbiologists want to be more proactive in helping patients with STIs,” says Professor Ison. “We have made advances in diagnosis by using molecular tests such as the nucleic acid amplification tests (NAATs) which give us a more accurate results, faster turnaround times and can be used with non-invasive samples. These tests can be used for screening in specialised sexual health care clinics and in primary care. However they need to be carefully validated before use.”

“While the advances in technology have enabled progress in many areas, the new tests should only be used by experts who understand their advantages and disadvantages and can interpret the test results properly”, says Professor Ison. “We are very concerned that some of the new tests are being offered for sale over the internet, for home use, when they should really only be used in clinics”.