Ureaplasma (spp NAA): What a Positive or Negative Result Means

At a Glance

This test looks for Ureaplasma DNA in urine or a genital swab and reports it positive (detected) or negative (not detected). If your report reads "Ureaplasma spp NAA": spp is the species group, and NAA is nucleic acid amplification, the technique that copies and detects bacterial DNA.

Two things matter more than the word on the report:

• Finding Ureaplasma is not the same as finding a cause. In a study of 1,272 non-pregnant women at a Melbourne sexual health service, most of them symptomatic, U. parvum was detected in 72% and U. urealyticum in 32% — and neither was associated with symptoms or signs.
• Routine testing for it is not recommended. CDC advises against testing for these organisms when evaluating cervicitis, and the European STI Guidelines Editorial Board advises against "routine screening of asymptomatic men and women or routine testing of symptomatic individuals". The test is nonetheless sold on panels ordered directly by consumers.

This is not a blood test: it is run on urine or a swab.

How to read your result

The result is one of two words, and positive is the one that needs explaining. Negative means no Ureaplasma DNA was amplified from that sample. Positive means it was — which, given how common detection is, raises a question the word does not answer: not what does this disease mean, but is this a disease at all. The rest of this page takes positive first.

What a positive result means

Ureaplasma DNA was detected. That is a finding about what lives in your urogenital tract, not by itself a diagnosis.

The evidence distinguishes colonization — the organism being present — from infection — the organism causing disease. For Ureaplasma the first is common and the second is hard to establish.

The evidence behind that. Plummer and colleagues studied 1,272 non-pregnant women at a Melbourne sexual health service, selected for having genitourinary symptoms or wanting an STI screen; 1,081 reported at least one symptom. U. parvum was detected in 910 (72%) and U. urealyticum in 403 (32%). Asked whether detection tracked with symptoms and signs, the authors reported that "Ureaplasma spp. were not associated with symptoms/signs." Their conclusion: "These findings do not support routine testing for M. hominis, U. urealyticum, and U. parvum in nonpregnant women."

The non-association is the finding, not the percentage. These are detection rates in a symptomatic clinic population, not a measure of how common Ureaplasma is in the general public. In a group where most people did have symptoms, having Ureaplasma did not explain them.

The European STI Guidelines Editorial Board reached the same place from the clinical side. Its position statement records that "Asymptomatic carriage of these bacteria is common and the majority of individuals do not develop disease", and — about testing and treating people who test positive — "At present, we have no evidence that we are doing more good than harm." It also notes that treating carriage "may result in selection of antimicrobial resistance", and that "eradication is not strongly associated with cure".

So a positive result on its own does not establish that Ureaplasma is causing anything you are experiencing. Take it to the clinician who ordered the panel, alongside any symptoms, rather than reading it as an infection to be cleared.

The two species are not the same finding

The report may name Ureaplasma parvum, Ureaplasma urealyticum, or just Ureaplasma species. Where it names only the genus, the distinction below is one the result does not make for you.

• Ureaplasma parvum is the more common of the two and the one with the weaker case for causing disease. The European position statement cites a meta-analysis of case–control studies that "demonstrated no association of U. parvum with NGU" — non-gonococcal urethritis — and notes that U. parvum "is detected more often in controls than cases in most studies." For people who test positive for U. parvum, the statement records that "subsequent antimicrobial treatment of positive men or women is currently not recommended."
• Ureaplasma urealyticum has a narrower and conditional association. The same statement says it "has been associated with urethritis in men, it is probably not causal unless a high load is present", and that "Only men with high U. urealyticum load should be considered for treatment." CDC puts it as "The majority of men with Ureaplasma infections do not have overt disease unless a high organism load is present."

A standard qualitative NAA result does not report load. It reports presence.

There is one setting where the European statement says testing can be considered. For a man with symptomatic urethritis, once gonorrhea, chlamydia, Mycoplasma genitalium and trichomonas are excluded, it says that if testing is undertaken "quantitative species-specific molecular diagnostic tests should be used", and that "Only men with high U. urealyticum load should be considered for treatment." That pathway needs a quantitative test; the positive/negative result this page describes is a different assay.

Is Ureaplasma a sexually transmitted infection?

It is not treated as one by the bodies that write the guidelines.

These organisms are discussed inside sexual-health guidance and can be present in sexually active people, which is why panels include them and why the result can arrive alongside chlamydia and gonorrhea. But CDC does not recommend testing for them, and states that "No specific evidence exists for a role for Ureaplasma parvum or Ureaplasma urealyticum in cervicitis" and that "Data are inconsistent regarding other Mycoplasma and Ureaplasma species as etiologic agents of urethritis." The European statement advises against routine screening and routine testing for these organisms, and against treating people who test positive outside the narrow case above.

A positive result is therefore not evidence of a sexually transmitted infection, nor evidence about a partner's behavior. Whether a partner should be told or tested is a conversation for the clinician — not something this result settles.

What a negative result means

No Ureaplasma DNA was amplified from that sample. Since routine testing is not recommended, a negative result mostly closes a question routine practice would not have opened. It says nothing about chlamydia, gonorrhea, Mycoplasma genitalium, trichomonas or anything else not on the panel, and it does not explain symptoms that are still present.

If you remember only one thing

A positive Ureaplasma result is usually colonization, not a diagnosis. In a study of 1,272 non-pregnant women attending a sexual health service in Melbourne, most of whom had symptoms, detection was not associated with symptoms or signs — in a group that largely had symptoms. Routine testing for these organisms is not recommended, and treating a positive result is not recommended outside one narrow case in men with symptomatic urethritis. If you have symptoms, they need explaining — but this result is not the explanation until a clinician says it is.

Two people, same result

Two people both have a positive Ureaplasma spp NAA result.

The first ordered a direct-to-consumer panel out of caution and has no symptoms. Hers is a genus-level result that does not say which species was found — an organism routine testing is not recommended for, and that was not associated with symptoms in the study above.

The second has had burning on urination for three weeks and was tested while working that up. Same word, different situation — not because the result means more, but because the symptoms do. What is causing them is the question, and a positive Ureaplasma is one finding a clinician weighs, not the answer.

Nothing in the result distinguishes them. Symptoms do, and so does why the test was ordered.

What this result cannot tell you

It cannot tell you whether Ureaplasma is causing your symptoms. Detection and causation come apart here, and the gap is wide.

It cannot tell you the organism load — the one variable the evidence suggests matters for U. urealyticum in men. A qualitative NAA reports presence, not quantity.

It cannot tell you when you acquired it, or from whom. Detection is common and says nothing about timing.

It cannot tell you whether you need antibiotics. That is a clinical judgment, and the guidelines lean against treating carriage.

It does not speak to pregnancy. The study quoted throughout this page examined non-pregnant women by design. Pregnancy is a different clinical context and a question for the clinician managing it.

Common interpretation mistakes

Reading "positive" as "infected." Present and causing disease are different, and for Ureaplasma the gap between them is wide.

Treating a positive result as proof of an STI, or of a partner's behavior. The guidelines do not treat detection as an STI diagnosis.

Assuming the two species mean the same thing. A meta-analysis found no association of U. parvum with NGU; U. urealyticum has a conditional association that depends on load.

Assuming a positive result needs clearing. The European statement notes that eradication "is not strongly associated with cure" and that treating carriage can select for antimicrobial resistance.

Reading a negative result as an all-clear for sexual health. It covers Ureaplasma and nothing else.

Expecting this page's figures to apply in pregnancy. They were measured in non-pregnant adults.

Questions your doctor may ask

Do you have symptoms — discharge, burning, pelvic or testicular pain — and for how long? Who ordered this test, and what prompted it? Was it part of a larger panel, and what else was on it? Have chlamydia, gonorrhea and Mycoplasma genitalium been excluded? Any recent antibiotics? Are you pregnant or trying to conceive? And what would change in your care depending on the answer?

Read together with

Mycoplasma genitalium is the organism in this family with an established role in urethritis — the one worth having a result for if symptoms are being worked up.

Mycoplasma hominis is tested on the same panels and sits under the same CDC sentence advising against testing.

Chlamydia and gonorrhea are the organisms CDC's urethritis and cervicitis guidance is actually built around, and the results worth checking when a urogenital panel comes back mixed.

Clinical pearls

Reported on some panels as "Ureaplasma spp NAA": spp = species group, NAA = nucleic acid amplification.

U. parvum was detected in 72% and U. urealyticum in 32% of 1,272 non-pregnant women at a Melbourne sexual health service, 1,081 of whom had symptoms; neither species was associated with symptoms or signs.

CDC: testing for U. parvum, U. urealyticum and M. hominis is not recommended.

A meta-analysis found no association of U. parvum with NGU; U. urealyticum is "probably not causal unless a high load is present".

Qualitative NAA reports presence, not load — and load is the variable the U. urealyticum association depends on.

Treating carriage may select for antimicrobial resistance, and eradication is not strongly associated with cure.

Clinical Takeaway

A qualitative nucleic-acid amplification test for Ureaplasma DNA in urine or a genital swab, reported positive or negative and labeled on some panels "Ureaplasma spp NAA". Detection is common and poorly tied to disease: in 1,272 non-pregnant women at a Melbourne sexual health service, most of them symptomatic, U. parvum was found in 72% and U. urealyticum in 32%, and "Ureaplasma spp. were not associated with symptoms/signs." The two species differ — a meta-analysis found no association of U. parvum with NGU, while U. urealyticum "is probably not causal unless a high load is present", which a qualitative assay does not measure. Routine testing is not recommended — CDC advises against it in evaluating cervicitis, the European STI Guidelines Editorial Board against "routine screening of asymptomatic men and women or routine testing of symptomatic individuals", with one conditional exception: quantitative species-specific testing in men with symptomatic urethritis after established pathogens are excluded, treating only at high U. urealyticum load. Eradication "is not strongly associated with cure" and treatment "may result in selection of antimicrobial resistance". The evidence covers adult men and non-pregnant women; the European statement says the relevance of these bacteria "in pregnancy or in neonates was not addressed". A positive result belongs with the clinician who ordered the panel, read against symptoms rather than on its own.

In one sentence

A common urogenital organism, detected by DNA amplification and reported positive or negative — found in most of a 1,272-woman sexual-health-clinic study and not associated with symptoms even there, and not a test recommended for routine use.

Bottom line

If your result is positive, the most likely explanation is colonization rather than infection: in the study above, detection was not associated with symptoms or signs even in a group that largely had them. It is not by itself an infection, not by itself an STI, and not by itself a reason for antibiotics. If you have symptoms, they still need explaining, and a clinician weighs this result against everything else on the panel. If your result is negative, it closes one question and leaves the others open. Neither the study nor the guidance quoted here covers pregnancy or newborns. Either way the result belongs with the clinician who ordered it.