tests for chlamydia

[fionawalsh]

Dear Dr.,

Greetings from Ireland.

I was wondering what test(s) are generally recommend for chlamydia. I ask because I was tested for chlamydia with
the PCR swabs (the standard test in UK and Ireland) in March 2010 and Sept 2008 and both results were negative, however I have just tested positive for chlamydia in a test by the greek lab (Locus Medicus http://www.locus-medicus.gr/), this lab tests menstrual blood for the presence of chlamydia DNA. This test was recommended by a fertility specialist I am seeing who is based in London, Dr. Gorgy (http://www.fertility-academy.co.uk), I and my husband having been trying to conceive for 3 years now and have unexplained infertility. Yesterday I requested more information from the lab and here's what I've got to date (not enough, I've requested more information) "This test has 95% percent sensitivity due to the fact that it comes from tissue directly from the uterus. It is not swab test, this is PCR test and examines DNA." I would appreciate if you could please kindly advise what test(s) are generally recommend for chlamydia and also if I get these tests carried out remotely from Ireland.

Thanks in advance for any assistance you can provide and kind regards,
Fiona

[H. Hunter Handsfield, M.D.]

Welcome to the STD forum.  I'll try to help.

There are at least 3 technologies that can be used to detect the DNA of infecting organisms.  All are generically called nucleic acid amplification tests (NAATs).  The 3 main ones are polymerase chain reaction (PCR), the DNA strand displacement assay (SDA), and transcription mediated [DNA] amplification (TMA).  Each has been used for commercially availalbe tests for chlamydia.  The most common trade names for these are (PCR was developed first and has the greatest name recognition.  Therefore, sometimes the term "PCR" is used to mean any NAAT -- just as Kleenex and Xerox are often used generically rather than for those particular brands.)

To my knowledge, it is not true that PCR per se is the "standard" chlamydia test in UK and Ireland.  I'm pretty sure TMA and SDA also are in use.  But you may have read something that was using PCR in the generic way I just described.

The statement you quote about DNA testing versus swab is a bit of nonsense.  All of the above are DNA tests, and all can be done on any kind of specimen, whether taken with swab or not.  That quote sounds, frankly, like marketing hype, or that it came from someone who really doesn't know much about the clinic's services (or that you misunderstood something).

From your description or the website, I cannot tell which chlamydia test is being used in the fertility clinic you refer to.  However, doing any NAAT for chlamydia on menstrual blood is quite unusual.  Blood is not a standard or well studied specimen for chlamydia testing, and I would not guarantee the results are as accurate as for the standard, well studied specimens -- cervical, urethral, or vaginal swabs, or urine.  Indeed, most (maybe all) commercial manufacturers advise to avoid contaminating specimens with blood.

But it is entirely possible that your fertility clinic is using an excellent test with highly reliable results.  There's just no way I can know.  But my best guess is that you don't have chlamydia, i.e. that your two previous tests were accurate and the latest one falsely positive.  Of course, if there is any doubt it is best to be treated for presumed chlamydial infection, rather than take the risk of a smoldering untreated infection.  But don't get your hopes up that treatment will solve your infertility problem.

You might consider consulting with your nearest GUM clinic, which will have highly expert advice and likely knows more about the local scene than I do -- and perhaps knows something about your infertility clinic as well.  I don't know where Ireland you are, but the Dublin GUM clinic is superb; you could not go wrong by consulting with them.

Best wishes--  HHH, MD

[H. Hunter Handsfield, M.D.]

The links you provide go to the manufacturer and essentially marketing statements.  It is easy to get a patent or even marketing approval in some countries with little scientific backing on actual test performance.  Most important, there is nothing about that test in the medical/scientific literature.  I would not trust it at all and therefore I continue to doubt you had chlamydia.

That's as far as we can go on this thread.  Take care.

[fionawalsh]

Dr. Hansfield,

This is invaluable guidance, many many thanks. Would your colleague possibly also give me his/her opinion on another (this is the last test, I promise) Chlamydia test that uses menstrual blood, I have posted the test specification here---http://www.scribd.com/doc/30583365 and here http://www.scribd.com/doc/30583457

Thanks again,

Best wishes,
Fiona

[H. Hunter Handsfield, M.D.]

I already heard back from my colleague.  To quote him exactly: "This is flat out nonsense."  Among other things, the test you describe isn't even DNA test, but a rather old fashioned method called DFA (for "direct fluorescent antibody").

MedHelp moderators are supposed to avoid criticizing questioners' own doctors.  But you should be aware that your doctor and his clinic are known in the chlamydia research community and are considered outside the mainstream.

[H. Hunter Handsfield, M.D.]

I am not an expert in the biology of chlamydia.  However, based on what I know, my belief is there is no scientific basis for the explanation you attribute to Dr. Toth or his clinic.  But I'm going to forward your comments to a colleague, one widely regarded as one of the world's top chlamydia biology experts.  I'll let you know what he says.

[fionawalsh]

Dear Dr. Handsfield,

Thank you for your very informative and considerate response. My husband and I have started treatment for Chlamydia, with the understanding that this will probably have no impact on our infertility issues.

Once we have been treated I intend on getting retested. So just one final question, a Dr. Toth in New York (http://www.fertilitysolution.com) has explained that his lab's test for identifying Chlamydia is different from the tests that are currently the international standard (the 3 you have kindly advised in your post). He has explained that the reason why is, the current standard technologies single out one or two surface markers on the Chlamydia bacterium for identification, so there is a very small possibility that if the bacterium has mutated it can suddenly stop producing that or the other selected markers and then you test negative. He produces his test locating serum in animals and it has affinity against all the surface proteins of Chlamydia. So if out of a thousand surface proteins the bacterium decides not to produce two or three, his serum will find the other 977 and zeros in and flags the Chlamydia. They use fluorescence microscopy to identify the bacteria. In your experience I would really welcome your thoughts on this test approach and whether you think it may or may not be more robust then the current international 3 test standards.

Many thanks in advance for your assistance.

Best wishes,
Fiona