Incubation time and test of cure of Chlamydia trachomatis

Chlamydia trachomatis (CT) causes a sexually transmitted disease with major
public health consequences due to its frequent asymptomatic nature.
Interrupting the route of transmission by timely identifying and treating
patients with CT, is an essential intervention in the prevention of this STD.
In the Netherlands, the yearly number of CT infections is estimated at 60.000.
Currently, Ct detection is regularly performed for diagnosis by using
commercially available nucleic acid amplification test (NAAT: PCR or SDA). NAAT
is highly sensitive and specific (>99%). Ct is diagnosed among others on
self-taken vaginal swab (women) or anal swab (men and women) which is a valid
and well accepted method by both male and female clients. For research and
diagnostic purposes a very sensitive and specific in-house PCR was developed as
well as a method to test for bacterial load (laboratory of Immunogenetics,
VuMC, head Servaas Morré). RNA can be detected as well, e.g. by TMA (GGD
Amsterdam). Both for DNA and RNA detection of Chlamydia trachomatis sample
collection at home followed by mail delivery is possible.
Fortunately good treatment is available for Ct: present treatment protocols are
based on one dose oral antibiotic therapy resulting in successful compliance.
It is generally assumed that the standard treatment methods are sufficient to
eliminate disease and no microbiological follow-up assessment is recommended.
Sometimes, in case of persistent complaints, pregnancy, for reassurance of the
client, or potential exposure to a positive source, retesting after 3-4 weeks
with NAAT is advised to determine if the infection is properly cleared. In most
cases the *test of cure* is recommended not earlier than 3 to 4 weeks after
treatment because of possible false positive results by the presence of
inactive cell components of Ct. However, there is discussion on the optimal
moment of retesting to assess effectivity of treatment. Advise on moment of
retesting is based on older studies in which the antibiotic treatment was in
most cases different from the current treatment and when the one-dose
antibiotic treatment was not yet the standard of care. Most studies also did
not include RNA assessment, which indicates that viable Ct is present.
Moreover, the current sample method used for CT screening and diagnostic
testing in STI clinics and national screening programs (vaginal and anal
self-swab) is not studied before.

Assess duration of Ct positivity in the 8 weeks after treatment as well as the
Ct bacterial load and RNA in time-sequential samples

Prospective cohort study
During 8 weeks after CT treatment at fixed intervals 17 self-swabs will be
taken and three times a short questionnaire will be filled in

A self-taken vaginal swab or anal swab is a non-invasive procedure in line with
the regular sampling at the STD clinic. (High performance and acceptability of
self-collected anal swabs for diagnosis of Chlamydia trachomatis and Neisseria
gonorrhea in men and women, manuscript in press STD) Self swab is reported by
clients to be an easy to perform method and they would take it again if
necessary. It will take about half to one minute to take a self swab. In total
the participants are asked to take 17 samples. Patients will participate
individually and no specific groups are targeted.
Thus risks associated with participation are absent or minimal.
Results of this study on the period of detection of CT after treatment,
bacterial load and RNA will contribute to the development of
'evidence-based'patient management and on the decrease of spread of CT in the
population.