Chlamydia and gonorrhoea are the most common treatable bacterial sexually transmitted infections diagnosed within theUnited Kingdom. Most sexual health clinics now use Nucleic Acid Amplification based Tests (NAATs), which test for DNA sequences particular to the organism in question, to diagnose these infections.
These tests are highly sensitive and specific but can remain positive for a while after the infection is successfully treated with antibiotics. This is because NAAT tests, unlike bacterial culture, do not distinguish between live and dead organisms. This means that if individuals are retested too soon after completing treatment, their test result will still be positive from the initial treated infection. We do not know for how long this will be the case, making interpretation of repeat tests difficult.
This is particularly important in clinical practice, where where a test of cure is recommended, such as in pregnancy and after gonorrhoea. The research will allow better interpretation of test of cure results, thereby avoiding the need to retreat individuals and their partners with antibiotics unnecessarily.
The proposed project will follow up individuals known to have chlamydia or gonorrhoea who have been treated as per national guidelines and then retested every week (using NAAT tests) for the initial infection until this is no longer detected. Non-compliance and possible re-infection will be ruled out through structured questionnaires during the follow up period.
This is a collaborative study in conjunction with centres in London. STIRF will be funding the part of the study to be performed in Manchester.
Title of project: Testing for chlamydia and gonorrhoea: persistence of a positive test result after successful treatment.
Lead researcher: Dr Gabriel Schembri
Place of Research: Manchester Centre for Sexual Health, Manchester Royal Infirmary.
Collaborating Centres: Sexual health centres in London
Proposed Duration of Study: One year
Funding from STIRF: £27,000 (subject to satisfactory report at six months)