Ear swab

An ear swab is a microbiological test that detects bacteria causing ear infection in a sample taken from the outer ear canal. It is performed when an ear infection produces discharge, persists despite treatment or recurs, because the result identifies the pathogen and the medicines to which it is susceptible.

Who is this test for

• people with outer ear canal inflammation and substantial discharge;
• people whose symptoms persist after approximately two weeks of ear-drop treatment;
• people with ear infections that recur or last for months;
• people with ear discharge and a perforated eardrum, ventilation tube or previous ear surgery.

Contact a doctor or emergency department immediately if ear pain is accompanied by a high fever, swelling, redness or tenderness behind the ear, facial muscle weakness, a severe headache or a stiff neck. Also seek urgent care if you have diabetes or weakened immunity and severe, persistent ear pain.

What an ear swab shows

Inflammation of the outer ear canal (otitis externa) is most often caused by bacteria, primarily Pseudomonas aeruginosa and golden staphylococcus (Staphylococcus aureus). Less commonly, the cause is a fungus such as Aspergillus or Candida, particularly after prolonged antibiotic ear-drop use. Water in the ear after swimming, cleaning with cotton buds, hearing aids and skin diseases such as eczema favour this inflammation.

The report lists bacteria found and, if necessary, an antibiogram, meaning a list of antibiotics to which they are susceptible. Skin bacteria also live in healthy people’s ear canals, so results are always interpreted alongside symptoms. A swab does not detect viruses.

Middle ear infection occurs behind the eardrum, which an ear-canal swab cannot reach. A swab is therefore useful only when discharge comes from the ear, for example with a perforated eardrum or a ventilation tube.

A swab is generally unnecessary for uncomplicated outer ear canal inflammation that settles quickly with drops. A swab is also not performed for acute middle ear infection with an intact eardrum, common in children; a doctor diagnoses it by examining the ear.

Preparation and sample

• The swab is best taken before treatment begins. Do not put drops or ointments in the ear the day before sampling unless your doctor has told you otherwise. If you have already used them or are taking an antibiotic, mention this at sampling.
• Wash the outside of the ear as usual, but do not clean the ear canal with cotton buds or rinse it, so that enough discharge remains for testing.
• The entrance to the ear canal is cleaned first, then a sample is carefully taken from the canal using a sterile cotton swab. Collection takes a few seconds. If the canal is inflamed, it may be uncomfortable, but the swab does not enter deeply or touch the eardrum.

How results are interpreted

A negative result, often described as normal flora, means no significant bacteria were found. If symptoms persist, a doctor looks for another cause, such as eczema, an allergic reaction to drops or an earwax blockage.

A positive result lists bacteria found. Outer ear canal inflammation is usually treated with ear drops because the medicine reaches a much higher concentration in the canal than tablets; an antibiogram is particularly useful when initial treatment has failed. A doctor decides on treatment based on the result, ear examination and your symptoms.

How to arrange testing

A nurse takes ear swabs at all our branches without an appointment or referral (branches are listed on the Contactpage). Prices for all tests and panels are listed in the service price list.

Frequently asked questions

Does an ear swab hurt?

No. The swab enters only the outer ear canal and does not touch the eardrum. If the canal is inflamed and swollen, contact may be briefly uncomfortable.

Can I use ear drops before the swab?

If possible, the swab is taken before treatment begins; do not put drops or ointments in the ear the day before. If your doctor has already prescribed drops, do not stop them yourself; mention this at sampling because they can affect the result.

What does Pseudomonas in an ear swab mean?

Pseudomonas aeruginosa is a bacterium that thrives in moisture and one of the most common causes of outer ear canal inflammation, particularly in swimmers. Together with symptoms, it points to the cause of infection, and the doctor chooses appropriate drops or another medicine based on the antibiogram.

Does a child need an ear swab for middle ear infection?

Generally not. Middle ear infection occurs behind the eardrum, and an ear-canal swab does not identify its cause. A swab is useful only when pus drains from the ear or the infection persists despite treatment, as decided by a paediatrician or ear, nose and throat specialist.