A report back on Miss Nicole Lima's presentation 'VITA RT-PCR, A MOLECULAR TEST FOR THE DETECTION AND DIFFERENTIATION OF VIABLE AND DEAD CHLAMYDIA TRACHOMATIS'

The final presentation of day 1 of the conference proved rewarding as Nicole Lima introduced us to the VITA RT-PCR, a molecular test which allows for the differentiation of viable and dead Chlamydia trachomatis and the potential impacts this test could have on clinical practice.

Current testing for Chlamydia using nucleic acid amplification tests detect the DNA of Chlamydia but tells us little about its viability. DNA can persist for a long time after effective treatment of Chlamydia and in patients who have been exposed to but self-cleared Chlamydia.

Many clinicians would be familiar with the dilemmas created by the need to wait 3 weeks for a test of cure due to concerns about detecting the DNA of non- viable Chlamydia.

Unlike DNA, we were reminded that RNA is generally only seen when Chlamydia is replicating.

My understanding was that VITA amplifies both RNA and DNA and gives a ratio of RNA to DNA. This ratio is used to produce a viability index.  As such a positive test using VITA is more indicative of an active infection than the standard NAAT.

VITA was recently trialled in a study at the Albion Centre in Sydney which enrolled 20 asymptomatic male patients with rectal chlamydia. Swabs were collected for NAAT, VITA and culture on the day they presented for treatment, day 0, again on day 7 after completion of treatment with doxycycline and at day 35, when a test of cure would typically be done.

The results are promising and suggest that VITA could be used to determine viability of infection at the time of diagnosis and could enable an earlier test of cure.

Author bio: Suzanne is a GP who has worked extensively in rural and remote Australia as well as in Sydney with a special interest in Aboriginal and Torres Strait Islander Health. She is currently working towards a Fellowship of Sexual Health Medicine and is working as a Sexual Health Advanced Trainee at Sydney Sexual Health Centre.