[Question #3940] Chlamydia Test Indeterminate

33 months ago
I had condom-protected intercourse with a woman 18 days ago.  Two weeks after the exposure, I tested for gonorrhea and chlamydia with an online NAAT amplification urine test. I received the results today.  The gonorrhea test was negative. However, the chlamydia test was indeterminate.  The notes on the result indicate that the initial result was a weak positive, but a repeat test on the same specimen was negative.  What are the chances that I am truly positive for chlamydia?  What do you recommend as next step?
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
33 months ago
Welcome to the forum. Thanks for your question.

You have come to the right place with this question, in more ways than you could have guessed. See below, after my reply.

Almost certainly you do not have chlamydia. Indeterminate or weakly positive results are uncommon, but in most cases they prove out as negative, as in your case. It would appear your laboratory undertook confirmatory testing, perhaps by repeat analysis with a different manufacturer's chlamydia test, or with specific confirmatory test procedures available for some tests. You could contact the lab and see if they can reveal exactly what confirmatory tests were done. Or you could simply have another test, which the lab might offer at no cost in this situation. But in the meantime, you can be confident you don't have it. Among other things, with condom protected sex, you obviously were at little or no risk for chlamydia, even if your partner was infected.

I am currently attending the world's top chlamydia research conference, which occurs every 4 years -- the International Symposium on Human Chlamydial Infections (http://www.ishci2018.nl). Dr. Hook and I are seated together, and this response includes his perspectives as well as my own (which are identical). In fact, as I opened your question, the topic of discussion was diagnostic testing for chlamydia:  perfect timing! Before answering, I discussed it with 3 of the world's top experts in chlamydia diagnosis, as well as the chief scientific officer for Hologic, the company that produces the most commonly used chlamydia/gonorrhea combination test (Aptima). My comments above represent the consensus of all of us.

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD
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33 months ago
Thank you Dr. Handsfield. Perfect timing indeed - I am grateful to you and your colleagues for the reassurance.  I do plan to retest with a new specimen just to be sure, along with HIV and syphilis tests.  I am grateful for your expertise and service.
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
33 months ago
Thanks for the thanks. I'm glad to have helped.---
32 months ago
Follow Up #1 - I went to the STD Clinic at the Public Health Department at 3 weeks post-exposure for new tests of Chlamydia & Gonorrhea (NAAT), Syphilis (CIA), and HIV p24/Ab Duo (CIA). All were negative.  This confirms what you and your colleagues thought regarding my indeterminate test.  My follow up question is this - since it was only at 3 weeks, should I retest in the future for HIV and Syphilis? I know my risk was very low due to condom protection, but  want to rule our any possibility. I am now at 4 weeks post-exposure.  Thanks.
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
32 months ago
Whenever any STD testing is done, it is routinely recommended that syphilis and HIV testing be included. However, the risk of either of these from a single exposure like yours is exceedingly low, and many STD clinics (including my own) often don't do them if the patient isn't keen on it (e.g. needle-phobic). In other words, it's up to you. However, since it's on your mind, you probably should do it:  most people worried enough to ask about it probably should be tested, just to remove any doubt. If you do it, wait until 6 weeks after the exposure to have both tests.

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