Detection of Chlamydia trachomatis antibodies in vaginal swabs as an intermediate marker for PID and tubal pathology * pilot study

Chlamydia trachomatis is a common sexually transmitted infection (STI) among
young people in the Netherlands. Chlamydia can cause infections higher in the
genital tract in women, so-called Pelvic Inflammatory Disease (PID) which can
lead to tubal pathology and have serious complications leading to infertility.
Chlamydia infection and PID remain asymptomatic in the majority of cases, which
makes treatment and prevention difficult. Recently a large Screening
Implementation has started among young people in the Netherlands, in order to
detect and treat more (asymptomatic) chlamydia infections. Predicting the
effect of such a program on later sequelae from infection (PID, ectopic
pregnancy and infertility) is complicated.
Availablity of an itermediate, more proximal and easy to measure marker for
tuba-pathology would facilitate the evaluation of screening programmes but also
to the course of Chlamydia-infection in a broader sense. If we can predict who
has an enhanced risk for complications, targeted interventions can be
developed, such as (frequent) screening or more intensive follow-up of
partners.

To asess whether the Chlamydia Antibody Test (CAT), used to determine the
presence of antichlamydia IgG antibodies in serum for diagnostics in the
fertility clinic, can serve as an intermediate marker for PID/tubal pathology
caused by Chlamydia.

For this pilot study, we plan to recruit women at two time-points in the path
from Ct-exposure and (infiltrating) infection towards PID and tubal pathology:
at the time of infection (women consulting STI clinics) and at the time of
confirmed longterm complications causing reduced fertility (women consulting
fertility clinics).
1. STI clinic Den Haag. Additional material will be collected during routine
sampling for STI-consultation, i.e. a vaginal swab and a blood sample from 25
recently infected women (Ct-positive NAAT-test) and matched to 50 women who did
not have a Ct-infection at the time of sampling (Ct-negative NAAT-test). Both
Ct-positive and *negative women will be asked to answer a few questions on
their medical history regarding STIs and PID. The samples will be sent to the
laboratory of the Dept Pathology at the VUMC for analyses
2. At the fertility clinics of Groningen and Maastricht Academic centres, we
will ask (retrospectively) women who have had a serological CAT in the previous
year, to participate in our study (25 CAT-positive and 50 negative). They are
requested to collect a vaginal self-sample at home and fill in a short
questionnaire and return this to the clinic by mail. Samples will also be sent
to the Dept Pathology, VUMC.

At the laboratory, the CAT will be performed on the vaginal samples from the
STI clinic and the fertility clinics and on serum from the STI clinic (serum
CATs from the fertility clinic are available from patient files). The bacterial
load of Chlamydia positive swabs (women with a current Ct-infection from the
STI clincic) will be assessed, and we will also quantify the Ct-antibodies in
vaginal mucosa and blood of CAT-positive women.

The burden for participants to the study is limited to filling in a short
questionnare (10 minutes), furthermore we make use of already available test
results (serum CAT in fertiltiy clinic), or we sample additional material
within a routine sampling procedure (vaginal swab and bloodsample in STI
clinic); only the vaginal self-swab for women who visited the fertility clinic
earlier, is additional. There are no further procedures; there are no other
risks to be expected.