# What else can cause a false positive Chlamydia screen?



## abclan

What else can cause a false positive chlamydia screen?

I was in the ER for an ovarian cyst and the ran a G/C screen. I was shocked when the lab called a week later to inform me I had a pos. chlamydia test. My husband and I have been married and totally monogamous for the last seven years. I have had routine clear paps in '98, '02 and '05. My midwife waw shocked as well and she is going to re-pap and run the g/c screen again.







: My dh's screen from our primary care MD was NEGITIVE.

Sooooo . . . .







what else can cause a false positive? Is there anything else I should be looking for or worried about? Is it possible I've had "low-grade" chlamydia for over seven years? SHould I just quit thinking about it because we'll never really know?


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## grisandole

I don't know, but I had the same thing happen over ten years ago....my PCP, who was awful, btw, said that I tested positive for it. I freaked out, since I'd been tested before and was neg, and my boyfriend and I at the time were careful. It didn't "feel" right to me, so I went to my former ob, who delivered ds1, and told her about it and did another test. It was neg.

In my case, my PCP was so horrible and so incompetent that I chalked the whole thing up to him. But maybe something can cause a false positive?


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## mwherbs

first of all a pap test is not a culture-- if you haven't been cultured in 7 years you may very well have had it all this time- and it could be a low level infection

what type of test was done- vaginal swab or urine? antibody screening? different types of tests have different causes of false readings.

because you have and ovarian cyst/pain in the the region is probably why the test was done.... and scaring from long term infection can be a cause of ovarian cysts, tubal abscesses/PID

so cell culture- 50-90% sensitive; 99% specific-- these tests don't mistake one germ/critter for another very often this test is known for it's false negatives -- there is a generation of women who used birth control and had PID/subsiquent infertility because of the lack of sensitivity of this test
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the tests listed below can have a higher number of false positives in a low-prevalence population- so a second test can be done culture, test for different antigen or different nucleic acid sequence , competitive probe

direct florescent antibody 50-80% sensitivity; 99% specific

Nucleic acid amplification ( urine test or swab - swab more sensitive for women) 80-92% sensitive; 99% specific

enzyme immunoassay (the most likely one done in an ER) 40-60% sensitive;99% specific

around 5% may be false positives but cross checking should reveal that it is a false positive

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here is a list of possible reasons for false positives-- the info below is derived by me from an article you can read at this address
http://www.ijmm.org/article.asp?issn...aulast=Malenie

Quality of endocervical swab can affect the incidence of false positive results because of its likely specimens collected contamination with vaginal secretions.
EIA has been reported to give false positive results in presence of gram positive bacteria including Staphylococcus aureus, Streptococcus agalactiae, Peptostreptococcus spp. and gram negative organisms including N. gonorrhoea. Acinetobacter spp ,, Salmonella More Details spp, E.coli and Gardenerella vaginalis.
and
can be due to the increased transportation time before the samples are processed and this had led to a loss of infectious particles/antigens.(4 days transport time)


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## Jane

Well, having clear paps doesn't mean that you don't have chlamydia unless that test is specifically requested.
If it were me, I'd be retested now and in 6 months just to be sure.
It's possible it was a lab mixup or a false positive. It's hard to say how many false positives there are because how would we know? People with a positive are given antibiotics, then tested again and found negative and the antibiotics are thought to have worked. The DNA probe testing procedures are quite accurate, though, in the testing that established it as the preferred method.
One last thought - did you go to the doctor with your husband and see/hear the result yourself? I am not trying to be insulting, as I don't know you or your husband, but I do know that someone who would cheat could be someone who would lie about a doctor's appt. Sorry to throw that one out there.


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## mwherbs

yea I would probably accept an RX because of the local and systemic implications/potential including a type of liver disorder/hepititis and it is implicated in arthritis --this disease is not over treated there is a long time pattern of undertreatment.


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## abclan

So glad to the responses - thanks!

Apricot - I know we've got to "ask the question". We did. But the answer, which I am totally confident in, is no. No one is stepping out here, KWIM?

Although I mentioned my paps were clear, my midwife told me often there are if excessive polymorphic neucleocytes present, it would indicate further investigation and testing. She has not run a g/c screen in the past because there were no indications or risk factors present.

mwherbs - thanks for the links and info!
The g/c screen the ER MD ran was a vaginal culture - don't know more than that. sorry. My midwife is going to run the DNA swab.
BTW, I am not sure I understand your last post. Chlamydia is connected to arthititis and heptatitis? Can you please help me understand? TIA!


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## mwherbs

here is the info-- I attempted to send 3x now hopefully this one will make it

Reiter Syndrome- a type of reactive arthritis from chlamydia.
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Rheumatol Int. 2006 Aug;26(10):879-85. Epub 2006 Jan 24.

Clinical presentations of chlamydial and non-chlamydial reactive arthritis.

Ozgul A, Dede I, Taskaynatan MA, Aydogan H, Kalyon TA.

Department of Physical Medicine and Rehabilitation, Gulhane Military Medical
Academy, 06018, Etlik-Ankara, Turkey. [email protected]

The aim of this study was to investigate the triggering micro-organisms and the clinical as well as laboratory differences between Chlamydial and non-chlamydial reactive arthritis (ReA) in a prospective study on 98 patients with acute/subacute arthritis. An inciting organism was found in 42 patients.
Eighteen of these were chlamydial. Fifty-seven percent of all ReA patients were carriers for HLA-B27, which increased to 67% in the chlamydial group. Chlamydial ReA patients had more urethritis (P<0.05) with a longer period between arthritis and inciting infection, significantly lower CRP levels, and involved joint counts (P<0.05). Additionally, sacroiliitis was more frequent besides extra-articular manifestations in chlamydial ReA group. This study shows that chlamydial ReA differs in some points from non-chlamydial ReA, which in turn may affect the evaluation of an arthritic patient. ReA due to chlamydia more frequently encompasses a monoarticular or oligoarticular clinical picture with predominant distal extremity involvement. Non-chlamydial ReA presents higher joint counts and may involve upper extremity joints.

PMID: 16432687 [PubMed - indexed for MEDLINE]
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the stats on peri-hepatitis women with PID 5-10% have been dx with this(it could be more but just like missed chlamydia)

Rev Prat. 2001 Dec 1;51(19):2081-5.

[Bacterial perihepatitis]
[Article in French]

Parolini I, Blanc P, Larrey D.

Service d'hepato-gastro-enterologie Hopital Saint-Eloi 34295 Montpellier.

The Fitz-Hugh-Curtis syndrome is a peri-hepatitis following a genital infection.
It usually occurs in young women. Chlamydia trachomatis is the most frequent
causal agent. Clinical signs include acute or recurrent pain in the right
hypochondria. Liver tests are not modified and the sonographic examination is
normal. Diagnosis can be suspected on the basis of serology, and formally
established by laparoscopy showing violin string-like adhesions. Prolonged
antibiotic treatment is effective.

PMID: 11842726 [PubMed - indexed for MEDLINE]


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## nznats

When I was 17 I got a positive test result... I had been with 2 people at that stage, the first person was regularly tested (as was I and had always had neg results) and he got a negative result, and my partner at the time was a virgin before me and he was negative also. I was given one dose of antibiotics and when I was tested again it was negative and I have not recieved any positive results since. I sincerely believe it was wrong, I do not believe I had it at all but I cannot account for the positive. It did not feel right as a PP said.


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## kyangel80

When my OB does my pap, they always do a swab as well to test for the gammit of things? I wonder what your MW's test will show? Possible fluke at the hospital lab is highly probable. I too had a supposed positive test for this once at a health center when I was 18. I immediately sent my boyfriend in to be tested at the request of the nurse and he came back neg? I still think it was wrong to this day, but who knows. I thought I had a UTI and had no symptoms of Chlamydia. I was treated with something that would have killed a horse so either way? What about catching it some other strange way. If your second test comes back positive.


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