An ear drainage culture is a lab test to check for infection-causing substances in a sample of fluid, pus, wax, or blood from the ear.
How the Test is Performed
A sample of ear drainage is needed. Your health care provider will use a cotton swab to collect the sample from inside the outer ear canal. In some cases, a sample is collected from the middle ear during ear surgery.
The sample is sent to a lab and placed on a special dish (culture media).
The lab team checks the dish every day to see if bacteria, fungi, or viruses have grown. More tests may be done to look for specific substances and determine the best treatment.
How to Prepare for the Test
You do not need to prepare for this test.
Why the Test is Performed
The test may be done if you or your child has:
- An ear infection that is not getting better with treatment
- An infection of the outer ear (otitis externa)
- An ear infection with a ruptured eardrum and draining fluid
It may also be done as a routine part of myringotomy.
Note: Ear infections are diagnosed based on symptoms rather than using a culture.
The test is normal if there is no growth on the culture.
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
Abnormal results may be a sign of infection by bacteria, virus, or fungus.
The test results may show which organism is causing the infection. It will help your doctor decide on the right treatment.
No risks are involved with swabbing the ear canal. Ear surgery may involve some risks.
Culture - ear drainage
Buttaravoli P, Leffler SM. Otditis extgerna (swimmer's ear), acute. In: Buttaravoli P, Leffler SM, eds.Minor Emergencies
Murray, PR. The clinician and the microbiology laboratory. In: Bennett E, Dolin R, Blaser MJ, eds.Mandell, Douglass, and Bennett's Principles and Practice of Infectious Diseases.
Update Date 8/30/2014
Updated by: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.