Nasal swab

A nasal swab is a microbiological test that cultures bacteria from a sample taken from the front of the nasal cavity. It is most commonly used to check for carriage of golden staphylococcus (Staphylococcus aureus), including methicillin-resistant strains (MRSA), for example before certain operations or in recurrent purulent skin infections.

Who the test is for

• people awaiting a planned operation or hospital admission, when the hospital or doctor requests a check for Staphylococcus aureus or MRSA carriage;
• people with recurrent boils (furuncles) or other purulent skin infections, either themselves or in household members;
• people with recurrent purulent infections and crusts at the front of the nose;
• people whose employer or healthcare institution requests a carriage check.

A swab is not useful for an ordinary cold and runny nose, since the cause is usually a virus. A swab from the front of the nose does not reliably identify the cause of sinusitis either, so a doctor makes the diagnosis through examination, and an ear, nose and throat specialist takes a sinus sample if needed.

What a nasal swab shows

Everyone has bacteria in their nose that do not cause disease. Approximately one in three people carries Staphylococcus aureus on their skin or in their nose, mostly without any symptoms; this is called carriage. A carrier can nevertheless transmit the bacterium to others or develop an infection themselves, such as a skin boil or a wound infection after surgery.

The sample is inoculated onto culture media. The report lists the bacteria found and, if necessary, an antibiogram, meaning a list of antibiotics to which the bacterium is susceptible.

A nasal swab does not detect viruses, so it is not a test for colds, influenza or COVID. Other tests are available for respiratory viruses, described on the page viral respiratory panel.

A nasal swab and a nasopharyngeal swab are not the same

A nasal swab is taken from the entrance to the nostrils, where Staphylococcus aureus is found. A nasopharyngeal swab is taken using a thin, flexible swab passed through the nostril to the back of the nasal cavity, above the throat. This is a different sample with different purposes, such as detecting whooping cough or respiratory viruses. If your doctor requested a nasopharyngeal swab, tell the nurse at the branch.

Preparation and sample

• The swab is best taken before antibiotic treatment, including antibiotic nasal ointments. If you have used these, mention it when the sample is taken.
• Do not use nasal drops, sprays, ointments or nasal rinsing solutions for at least 12 hours beforehand, and do not clean your nose on the day of sampling.
• A sterile cotton swab is moved in a circular motion along the inner wall of the front of both nostrils. Sampling takes a few seconds and is painless, but may cause sneezing or watery eyes.

How to interpret the result

A negative result, often described as usual flora, means that no significant bacteria grew.

If Staphylococcus aureus is isolated and you have no symptoms, this represents carriage, which generally does not require treatment in a healthy person. A doctor sometimes recommends removing the staphylococcus from the nose, for example before surgery or for recurrent skin infections. This is most commonly done with an antibiotic nasal ointment and washing the skin with an antiseptic, according to the antibiogram.

If you had the swab before a planned procedure, forward the result to your doctor and hospital, since the hospital uses special protective measures for antibiotic-resistant bacteria. Your doctor interprets the result alongside your symptoms and the reason the swab was taken.

How to arrange testing

A nurse takes the swab at all branches, without an appointment or referral. The branch list is available on the page Contact. Prices for all tests and panels are listed in the service price list.

Frequently asked questions

What does Staphylococcus aureus in a nasal swab mean?

Most often, it simply means you are a carrier, like many healthy people. This is not a disease and usually does not require an antibiotic. Your doctor decides whether it needs to be removed, based on the reason for testing and the antibiogram.

Is a nasal swab needed for a cold or sinusitis?

Generally not. Colds are caused by viruses, and bacteria from the front of the nose do not necessarily correspond to the cause of a sinus infection. A doctor requests a swab only when there is a specific reason.

Can I have nasal and throat swabs taken together?

Yes. If your doctor has requested them, both samples can be taken during the same visit. A throat swab is primarily used to detect streptococcal throat infection, whereas a nasal swab checks for staphylococcal carriage.

Does taking a nasal swab hurt?

It is painless. The swab enters only the front of the nostril, so the sensation is brief and mildly uncomfortable, and many people sneeze.