Ear drainage culture

• Illustrations
• Alternative names
• Definition
• How the test is performed
• How to prepare for the test
• How the test will feel

• Why the test is performed
• Normal Values
• What abnormal results mean
• What the risks are
• Special considerations

Alternative names    Return to top

Definition    Return to top

Ear drainage culture is a laboratory test to identify organisms that cause ear infections.

How the test is performed    Return to top

A sample of ear drainage either from the outer ear or middle ear is placed on culture media for the purpose of growing microorganisms (bacteria, fungus, or viruses) in the laboratory, which will later be identified.

The microbiologist inspects the cultures daily for growth. If microorganisms are detected, other tests may be initiated to determine the sensitivity of the organism to medications (sensitivity analysis). Antibiotic therapy can then be determined based on these results.

How to prepare for the test    Return to top

There is no preparation.

How the test will feel    Return to top

The specimen will be collected from a cotton swab placed gently inside the outer ear canal. No pain is associated with the test. However, ear pain may be present already if infection is suspected.

If a myringotomy (surgical opening of the eardrum) is performed for relief of a painful, bulging tympanic membrane in otitis media, fluid will be collected at this time. Rarely, a needle may be inserted through the tympanic membrane (eardrum) to obtain a sample of the fluid from the middle ear.

Why the test is performed    Return to top

The test may be performed for an infection of the outer ear (see otitis externa; acute), as a routine part of myringotomy, otitis media with ruptured eardrum and draining fluid, or otitis media not responding to treatment. Most ear infections are diagnosed by clinical symptoms rather than by obtaining a culture.

Normal Values    Return to top

No organisms seen on the culture is normal.

What abnormal results mean    Return to top

Abnormal results indicate infection. The infection may be bacterial, viral, or fungal. The causative organism and an effective medication to treat the organism, if available, may be indicated in the results.

What the risks are    Return to top

No risks are involved with swabbing the ear canal. Risks of myringotomy and needle aspiration include bleeding, infection, and hearing loss.

Special considerations    Return to top

Sometimes special stains of the fluid, such as a Gram stain or KOH stain, are done to help with the initial diagnosis.