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CHLAMYDIA/GC testing reliability?
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The STD Forum is intended only for questions and support pertaining to sexually transmitted diseases other than HIV/AIDS, including chlamydia, gonorrhea, syphilis, human papillomavirus, genital warts, trichomonas, other vaginal infections, nongonoccal urethritis (NGU), cervicitis, molluscum contagiosum, chancroid, and pelvic inflammatory disease (PID). All questions will be answered by H. Hunter Handsfield, M.D. or Edward W Hook, MD.

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CHLAMYDIA/GC testing reliability?

Hi,
35 yr. old male. "Symptoms": Light burning when urinating one day after receiving unprotected oral sex. No discharge and no itching. Burning gone third day.

1) How reliable is a NEGATIVE CHLAMYDIA/GC test done almost 6 days post exposure? The test was done by Quest Lab. Here are the test kit details:
This test was performed using the BD ProbeTec(TM) ET Chlamydia trachomatis and Neisseria gonorrhoeae Amplified DNA Assays.

I "think" I might have urinated about 45 mins. prior to giving the test.

2) What about NGU? My understanding is the the test I had done only pick up the trachomatis bacteria. Not: Ureaplasma urealyticum, Mycoplasma or Trichomonas. Could I have been infected with any of those?

I also tested negative for HIV and HSV-2. I'm aware that this is outside the "window period" but they came as part of the"package". I did not feel a test for syphilis was needed.

Thank you for your great service - PLEASE keep up ALL the good work. It is much appreciated!



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300980_tn?1194933000
Welcome to our Forum.  Your questions are similar to ones we are asked frequently and provide me with the opportunity to provide a somewhat more expansive answer than I sometimes do.  Let's go the questions:

1.  The new nucleic acid amplification tests (NAATS) such as the one you were tested with have been available for about a decade and are the most sensitive assays for detection chlamydial and gonorrhea infections that we have.  Before these tests were available, culture tests were the "gold standard" for testing for both of these pathogens.  With the availability of NAATS careful study has shown that even in expert laboratories, culture detected 30-40% less chlamydial infection and 10-15% less gonorrhea that these newer tests.  Are they perfect?, no, but they are more sensitive than anything we have ever had and they very, very rarely miss an untreated infection.   You should have confidence on the basis of the tests you have had that you do not have chlamydia or gonorrhea.  Recent urination does not meaningfully effect these tests.

2.  What about NGU.  NGU can be caused by bacteria other than chlamydia.  it is clinically recognized on the basis of symptoms such as the ones you describe when the findings are confirmed by laboratory testing which show increased numbers of white blood cells (WBCs) in either a swab specimen taken from the penis or in a urine specimen collected at the beginning of urination (if the specimen is taken in the middle of urination the WBC's may have been "flushed" out).  


I hope these answers are helpful to you.  It is clear from your test results that you do not have chlamydia or gonorrhea.  whether or not NGU was present is harder to be sure of withourt more information but it sounds unlikely.

Hope these comments are helpful to you.  EWH
13 Comments
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Avatar_m_tn
Thank you! Regarding NGU it sounds like the following test would rule it out? But what about Trichomonas - is that something that can be transferred through oral sex from female to male?

Mycoplasma/Ureaplasma, Real-Time PCR

Description: This test is used as an aid in the diagnosis of genital infections caused by Mycoplasma sp and Ureaplasma urealyticum. Ureaplasma species and M genitalium are causes of nonchlamydial nongonococcal urethritis in men. Mycoplasma species do not cause vaginitis, but they may proliferate in patients with bacterial vaginosis and may contribute to the condition. In humans, both Mycoplasma and Ureaplasma species may be transmitted by direct contact between hosts (ie, venereally through genital-to-genital or oral-to-genital contact), vertically from mother to offspring (either at birth or in utero), or by nosocomial acquisition through transplanted tissues. The speciman collected is a urine sample.

Thanks again!

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300980_tn?1194933000
Trichamonas is not transmitted by oral sex.  it sounds like things are in the clear. EWH
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Avatar_m_tn
thank you - sorry LAST question I promise!. I did have a complete urinalysis done back in mid March that read as follows.

Microscopic Examination:

WBC - 0-5 /hpf Ref.: range: 0 - 5
RBC - 0 -3 /hpf Ref.: range 0 - 3
Epithelial Cells (non renal) - None seen
Crystals - Amorphous Sediment - Abnormal
Mucus Threads - Present
Bacteria - None seen

Anything to be concerned about here? Also wouldn't a urinalysis like this pick up the any NGU related bacteria?

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300980_tn?1194933000
This urinalysis is "clean.  There is no indication of NGU.  Take care.  EWH
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Avatar_m_tn
Thank you Dr. Just to clarify; the urinalysis results posted was just meant as an example. The test was done prior to the unprotected oral sex encounter. I wanted to know if that level of details would reveal any potential NGU - from your response I conclude that it will.
I went and got another urinalysis done the other day as well as a Mycoplasma/Ureaplasma, Real-Time PCR test. I will post the results once I get them.
Thanks again.
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Avatar_m_tn
Got the urinalysis results and now I'm totally freaked out! Will please let me know your thoughts on this? I already scheduled an appointment with Primary but can't see him until tomorrow.
Is this something that I should be very, very concerned about? Like hiv concerned or something?
WBC Esterase 2+ Abnormal
WBC >30 Abnormal
RBC 4-10 Abnormal

Casts Presents Abnormal
Cast type Hyaline casts

Bacteria few

Thank you
The heart-pounding concerned!
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Avatar_m_tn
should also have mentioned that my current "symptoms" is a light discomfort in my scrotum - no pain or tender TCs to the touch. I can't feel anything when I run and workout which I just did 1hr ago.  I have no discharge or burning when urinating.
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300980_tn?1194933000
these results are compatible with NGU.  If that is what is present, it is easily treated.  Your PCP will be able to take care of things tomorrow,. EWH
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Avatar_m_tn
Crap! but thanks for the prompt response. Since I already tested negative for CHLAMYDIA/GC 6 days post exposure would you recommend a retake?
Also I did have sex with my partner about a week ago but she is not showing any signs of anything. I.e. discharge or burning. Do you recommend that she gets a urinalysis done as well? I know I have asked a lot of questions and feel bad. I don't mind paying for another one and just leaving it blank if you would like?
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300980_tn?1194933000
I see no reason for further testing. The tests are very good. furthermore, if your PCP does tell you that you have NGU, the therapy would clear chlamydia and most gonorrhea.  As for testing your GF- not needed.  If she is exposed and your doctor treats you, she should be treated as well, irrespective of what tests show.  This is the safest course of action.  EWH
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Avatar_m_tn
Thank you! 1mg of Azithromycin? not that I'm self-medicating just curious...
Thinking out loud: "what else aside from NGU could it be?"
I have already said it once but have to say it again; PLEASE, PLEASE continue your good work on this site. SO MUCH appreciated!
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300980_tn?1194933000
This will need to be the end of this thread.  Recommended therapy for NGU is either 1.0 gram of azithromycin as a single dose or doxycycline 100 mg twice daily for seven days.  

End of thread. EWH
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