[Question #9469] Testing accuracy

32 months ago

Good afternoon Doctors, I recently tested positive for chlamydia via anal swab, which as stated in my previous question was strange as I haven't had anal penetrative exposure or any exposure there.

I wanted some clarification regarding urine testing as I am wanting to confirm who is at risk re my partners.

1. I had a urine test done it was approximately an hour or more after my last void and was the first pass sample. This test was negative. Is it true that this is very accurate and that if I had chlamydia it would have soon? I read that this test can miss 10% of infections in unsympathetic males.

2. I have contact the person I believe I was infected by and told him. Do I need to contact my other partners ie heterosexual partners who I did not have oral with or any anal play with (noting I am not anally active).Dr. Handsfield did mention that he does not suspect that I put them at risk, i don't want to go worrying to many people unnecessarily.

3. Dr. Handsfield mentioned that I may have swallowed contaminated fluid and that this may have caused my postive rectal response, which I tend to agree with.

So my understanding is that my hetro partners are not at risk as I didn't expose them at all but I just wanted to confirm the about questions as well.

4. I have read that GI Tract chlamydia can continue to come and go after treatment and that researchers are not clear on the impact this has on the host but believe that this infection is benign and doesn't pose a risk to host or sexual partners not engaging in anal sex.

Sorry I know this might be repeating or reposting but I would appreciate the clarity and further information.

32 months ago

Oh and I have begun antibiotics 7 days 2 daily doxy

32 months ago

5. Also I meant to ask would a bowel movement just prior to testing impact the results of the swab test?

Edward W. Hook M.D.

32 months ago

Welcome back to the Forum. As you know, Dr. Handsfield and I share the Forum and by chance I happened to be assigned this follow-up. In preparing to respond, I reviewed your earlier interaction with Dr. Handsfield and agree with all that he said- your positive test is a mystery. As Dr. Handsfield said, currently available tests for chlamydia are among the most reliable tests in medicine with high sensitivity and few but occasional false positives. In addition to the possible causes of your your positive test mentioned by Dr. Handsfield, I'll add one more which is just as rare as falsely positive tests or positivity from swallowed genital secretions from an infected partner--there is also a VERY small chance that there was a lab error, either with cross contamination from another positive specimen or clerical error in recording. Irrespective, as Dr. Handsfield has already said, I doubt that you will ever have a conclusive answer to this mysterious result. With that, I'll address your follow ups:

Urine tests are very slightly less sensitive than specimens taken with a urethral swab but the difference is not statistically significant. The statement that urine chlamydial testing would miss up to 10% of infections in asymptomatic persons is a large overstatement

I agree with Dr. Handsfield. I see no reason to notify your other partners

3. Dr. Handsfield mentioned that I may have swallowed contaminated fluid and that this may have caused my postive rectal response, which I tend to agree with.So my understanding is that my hetro partners are not at risk as I didn't expose them at all but I just wanted to confirm the about questions as well.

Correct

Following successful treatment, tests for chlamydia may remain intermittently positive for up to a week or ten days due to the presence of dead chlamydia which have not yet been eliminated from the body. This is true for infection at all sites.

5. Also I meant to ask would a bowel movement just prior to testing impact the results of the swab test?

No, having had a bowel movement just prior to testing is not known to affect test results.

I hope this information is helpful EWH

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32 months ago

Thank you Dr Hook for your detailed and reassurance I feel more confident with the clarity you have provided. I apologise for going back again, logically I understand that there was no risk to my hetro partner but my confused mind re how I got a positive result made me concerned.

I have one final question I understand that the window period for HIV and syphilis is 6 weeks the recent test I did was approximately 5weeks and 2 days post exposure. To be completed clear should I retest for these? My only at risk behaviour was the incident I believe I was exposed orally recently.

Again thanks for the service you both provide having access to specialist Dr's with real experience is truly invaluable! Please don't ever retire!

Edward W. Hook M.D.

32 months ago

While "official" recommendations are to wait 6 weeks before results are conclusive, by 30 days results are actually almost entirely reliable for both syphilis and HIV testing. For HIV at 4 weeks about 99% of persons who are going to become positive will have done so and we have never seen or heard of a person's whose tests were negative at 4 weeks who went on to become positive.

If I were you, I would have complete confidence in your 5 week results. EWH

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32 months ago

Oh and with regards to your statement re contamination or clinical error could it be that my urine sample was positive and my swab was not? Or are they two different tests and processes?

Edward W. Hook M.D.

32 months ago

No, the urine and swab are processed separately. These tests are done in batches. I was suggesting that one other possible source of this mysterious result would be that an adjacent specimen from another person was positive and contamination or a clerical error was made in the lab.

I realize this is perplexing as as Dr. Handsfield already said, I doubt you will find a definite answer to how this happened. My advice is to do as Dr. Handsfield already suggested- take your doxycycline and do your best to move forward.

This completes this thread. I trust you will not need to return. Further "what if" questions will be unrewarding. EWH

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