Explanation

Mycoplasma hominis PCR (urine): what is measured?

Mycoplasma hominis is a small bacterium without a cell wall that is found in the genital organs of many healthy people without causing symptoms (carriership). The bacterium can be transmitted through sex, but is not counted as an STI, because it has not been shown to cause disease in adults. In women, it is mainly found in larger amounts with bacterial vaginosis (a disturbance of the normal bacteria in the vagina). The PCR looks for genetic material of the bacterium in the first part of the urine and does not say whether the bacterium causes symptoms.

What can it detect?

Presence of Mycoplasma hominis in the urethra; this is usually carriership without symptoms

Result

What does the result mean?

Positive result

A positive result means that the bacterium is present. This is common in people without symptoms and usually does not mean disease. According to a position statement of the European STI guidelines editorial board (IUSTI, 2018), there is no good evidence that Mycoplasma hominis causes inflammation or infertility in adult men or non-pregnant women, and it has not been shown that treatment does more good than harm. Treating a positive result without symptoms is therefore not needed. In men, according to that recommendation, a positive result often reflects the bacteria of a female partner.

Negative result

A negative result means that the bacterium was not found. Because Mycoplasma hominis also occurs in healthy people and is not a proven pathogen, a negative result has little meaning for your health. This result neither explains nor rules out urethral symptoms; tests for, among others, chlamydia, gonorrhea and Mycoplasma genitalium are intended for that.

After an abnormal result

With a positive result without symptoms, no treatment or follow-up check is needed according to the European recommendation. With symptoms, the GP first looks for other causes, such as chlamydia, gonorrhea, trichomonas or, in women, bacterial vaginosis. Mycoplasma hominis is not notifiable.

Reliability

How reliable is the test?

The PCR detects the bacterium reliably, but a positive result does not distinguish between carriership and an infection that causes symptoms. Mycoplasma hominis is not a proven pathogen: the evidence that this bacterium causes urethritis or other symptoms is insufficient. As a result, a positive result says little, both in people without symptoms and in people with symptoms.

What can affect the result?

A positive result does not say whether the bacterium causes symptoms; many people without symptoms also carry the bacterium.
In men, according to the European recommendation, the bacterium is not linked to urethritis.
Mycoplasma hominis is naturally insensitive to some of the common antibiotics and often does not disappear permanently after treatment.
If you urinated less than 1 hour before collecting the sample, or collect more than the first part of the stream, the sample is diluted and the test can miss an infection.

Preparation

Collect the urine when you have not passed urine for at least 1 hour.
Collect only the first part of the stream, not the middle part.

Who it is for

Who is the test useful for?

Useful for

The result usually does not explain symptoms, because the bacterium also occurs in many healthy people. Urethral symptoms more often fit chlamydia or gonorrhea, and, with symptoms lasting longer than 4 weeks, Mycoplasma genitalium. This test is not suitable for questions about pregnancy or fertility.

How common is it?

How often Mycoplasma hominis occurs in the Netherlands is not known, because it is not routinely tested for. In international research using PCR, the bacterium was found in 3 to 15 percent of sexually active women who were not pregnant. In men who visited an STI clinic, this was 2 to 4 percent; most people with the bacterium do not become ill.

Horner et al., European STI Guidelines Editorial Board (IUSTI), 2018

Drawbacks and risks

A positive result can lead to unnecessary treatment with antibiotics, with a risk of side effects and of resistance in this bacterium and in other bacteria, including the causes of real STIs.
A positive result can wrongly give the idea that you have an STI, resulting in worry or tension in a relationship.

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