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Laboratory: Clinical Microbiology
Test Name:
Test Code: EAR
Clinical Information:
Test Indications:
To aid in the diagnosis of otitis media.
Acute otitis media is an acute infection of the middle ear marked by the presence of fluid in the middle ear and inflammation. Acute otitis media with effusion is the clinical variant most associated with a bacterial etiology. The most common agents of otitis media are Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. Other less frequent causes include Staphylococcus aureus, Gram-negative bacilli, Streptococcus pyogenes and other beta-hemolytic streptococci. Rarely, anaerobic organisms, fungi, Nocardia and mycobacteria may be involved in cases of chronic infection and a pathogen is often not isolated.
The majority of cases of otitis media can be diagnosed clinically and if indicated, treated empirically without a microbiological diagnosis. Mild disease may be viral or due to less virulent bacteria (e.g., M. catarrhalis), resolving spontaneously with or without antibiotics.
Due to the invasive nature of the collection process, efforts to determine the cause of otitis media are only recommended in cases of complicated, recurrent or chronic persistent otitis media, and/or where previous therapy has failed. Middle ear fluid/tympanocentesis fluid, obtained as an aspirate, is the specimen of choice in both adult and pediatric patients. Swabs are not recommended due to contamination from flora of the ear canal, making interpretation difficult. A swab may be used when the ear drum has ruptured or as a result of a myringotomy and fluid can be collected (after cleaning the external ear canal).
Nasopharyngeal cultures have poor predictability for detecting otitis media pathogens and should not be submitted for that purpose. 
For fungal culture, mycobacterial/AFB culture, or otitis externa, refer to corresponding LIM entries below.

1. Do not label as “ear”. The sample type and/or site must be indicated, e.g., tympanocentesis fluid. Indicate left or right ear.
2. Indicate antimicrobial therapy on ordering requisition.
3. When possible, send fluid (aspirate) rather than a swab. The volume of specimen obtained using a swab as the collection device is suboptimal. Do not send a swab dipped in fluid.
4. Clearly indicate on the microbiology requisition the test(s) requested. If requests are being made for more than one test on a swab taken from a specific site, i.e., bacterial culture aerobes, bacterial culture anaerobes and/or fungus culture, please ensure that a separate swab sample is submitted for each test requested. Failure to provide separate swabs will result in sub optimal microbiology culture results.
5. A Gram stain result will automatically be provided.
6. Samples and requisitions must be labeled/completed in accordance with the Shared Health Specimen Acceptance Policy.
7. Accurate patient identification must be made prior to sample collection. Patient identification should be done in accordance with the site policy.

Patient Preparation Instructions:
Inner ear (fluid - preferred):
1. Sample must be acquired using aseptic technique, e.g., cleaning the ear canal with antiseptic solution, followed by surgical incision or needle aspirate. Follow protocols outlined by your health care facility for this sample type.
2. Submit in sterile screw-capped specimen container. Always submit as much sample as possible.
Inner ear (swab):
1. First clean the external ear canal.
2. Collect fluid or drainage using a swab and submit in transport medium.
Collection Devices:
Specimen Required: Middle ear fluid, Tympanocentesis fluid, Myringotomy tube drainage, Inner ear fluid or swab of drainage (Adult and Pediatric)
Reference Values:
Negative after 3 days incubation.
For positive samples, a descriptive report will be provided.
See Also:
More Information:
Specimen Handling:
Specimen must be delivered to the laboratory as soon as possible and ideally within 24 hours of collection.
Local (fluid or swab): ≤2 hrs, store at room temperature.
Courier/local storage (fluid): ≤48 hrs (≤24 hrs optimal), store at room temperature.
Courier/local storage (swab): ≤48 hrs (≤24 hrs optimal), store at 4°C.
Ensure samples that are being sent to a referral laboratory are packaged in accordance with Transport of Dangerous Goods recommendations for diagnostic samples.