Chlamydia trachomatis IgG ELISA's

Damian Bond damian.bond at virgin.net
Tue Jan 27 15:55:30 EST 1998


I have an interest in Chlamydia serology tests and believe that none of the
existing products satisfy the requirements of diagnosing patients at risk of
PID.

The clinical utility of Chlamydia serology goes as follows:

Most women are unaware of Chlamydial infection due to asymptomatic
infection. If they do have a clinically recognised infection, most have
stopped tetracycline treatment too early as symptoms subside and have a
latent infection termed the chronic phase. If untreated, it proceeds to form
vesicles, which can ultimately block tubes, causing PID and infertility.
Most clinicians agree with this scenario.

The use of Serology is widely disputed. Most clinicians claim that it is an
outdated technology and should be replaced by antigen tests or by PCR. I
think this is wrong for 2 reasons. The antigen tests only work if there are
significant levels of antigen present and this pre-supposes active
chlamydial  replication. By the time the infection has transferred from
acute to chronic, the disease has migrated from the easily sampled sites and
replication has almost stopped. PCR can only amplify DNA if it is present in
the sample. I have been unable to find references to PCR finding chlamydial
DNA in chronic infections. All the data relates to acute infection.

There is limited support for comparative analysis of levels of IgG and IgM
antibodies against Chlamydia. If there is a detectable difference in titre
between them, it predicts a slowly replicating chronic infection and is
therefore a diagnostic tool.

The data for this hypothesis is not conclusive. It is disputed by some
clinicians and even by some ELISA kit manufacturers. Some countries, such as
France and Italy, support it and they have large volumes of tests performed
covered by healthcare reimbursement. Other countries believe it is outdated
and inappropriate.

I personally believe that serology is an important factor. Instead of
ignoring pneumoniae, we should be looking for a panel of test that can
discriminate between trachomatis and pneumoniae. The early evidence linking
pneumoniae to cardiac address is going to raise the profile of Chlamydia as
a disease. If I can establish the evidence, or put together the appropriate
research organisation, I can raise funding for a company to develop the kit
reagents to address this problem. Maybe then we can eradicate this
pernicious disease.

What is lacking is definitive clinical trials on asymptomatic women,
compared against alternative detection methods.

To answer your question, I am aware of 3 companies providing ELISA kits for
Chlamydia antibodies.

The best is probably Savion - an Israeli company. They have the most
extensive range of kits, categorising between trachomatis, pneumoniae and
psitaci. They also have a high reputation for quality of their reagents.

Another company is Medac, a German company. They have kits for trachomatis
IgG, IgM and IgA. I do not know their cross reactivity for pneumoniae.

The other company is Trinity Biotech, Ireland. They make the Clark range of
ELISA kits in Jamestown USA. They have kits for IgG and IgA. They do not
have a kit for IgM which I consider a problem. I have heard dubious reports
of their quality. They are available in the USA via Wampole.

I would be interested in your reactions to my ideas. I am unclear whether to
proceed with it. It is either the most missed opportunity in a diagnostic
test to eradicate one of the most pernicious and prevalent diseases, or it
does not work. I suspect that in the past it did not work, because the
immunoassay kits did not have adequate specificity, but that can easily be
changed with new technologies.
Yours sincerely

Damian Bond
Tel 01244 347 483
Mobile 0498 600 833
e-mail damian.bond at virgin.net
kevin-ault at uiowa.edu wrote in message <65ctci$e7e$1 at flood.weeg.uiowa.edu>...
>Does anyone have experience with commercially available ELISA kits for
>Chlamydia?  I am specifically interested in IgG antibodies against
>Chlamydia trachomatis.  I am a gynecologist with an interest in
>infertility.  Antibodies against Chlamydia trachomatis are potentially
>a diagnostic test for infertile women because of the association of
>Chlamydia with tubal scarring and infertility.  I am looking for a kit
>with minimal cross reaction with C. pneumoniae, if such a kit exists.
>Please post to the group or e-mail me - Kevin Ault, MD  University of
>Iowa   (kevin-ault at uiowa.edu)
>





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