Laboratory: Clinical Microbiology
Test Name:
EAR, OUTER (OTITIS EXTERNA), CULTURE, AEROBIC BACTERIA
Test Code: EAR
Clinical Information:
Test Indications:
To aid in the diagnosis of otitis externa, an infection and inflammation of the external auditory canal.
Otits externa can be acute, chronic or malignant. Acute diffuse infections, sometimes referred to as “swimmer’s ear”, are frequently caused by Pseudomonas aeruginosa (freshwater otitis) or Vibrio alginolyticus (ocean exposure). S. aureus and S. pyogenes (group A) may also be involved.  Invasive or malignant otitis externa is a deep-seated infection that occurs when P. aeruginosa (95%) invades the cartilage of the ear, may progress to cellulitis or osteomyelitis and affects primarily immunocompromised or diabetic patients. Aspergillus and (less commonly) Candida species are the most frequently isolated fungi in cases of otomycosis.

Recommendations:
1.  Since a swab is used for collection, the specimen is often contaminated with external ear canal flora, including coagulase-negative staphylococci, viridans streptococci and corynebacteria.
2.  Vigorous swabbing is required after debris or crust has been removed since surface swabbing may miss pathogens.
3.  Obtain specimen prior to initiation of antimicrobial therapy. If not possible, indicate antimicrobial therapy on ordering requisition.
4.  Do not simply label as “ear”. The sample type and/or site must be indicated, e.g., right ear canal.
5.  Indicate current antimicrobial therapy on the requisition.
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:
Outer ear (swab):
1.  Use a swab moistened with sterile physiological saline to remove any debris or crust from the ear canal.
2.  Obtain sample by firmly rotating the specimen swab in the outer canal. Vigorous swabbing is required since surface swabbing may miss pathogens.
Collection Devices:
Preferred Device:
1 - eSwab  - Specimens received in other collection devices will not be processed.
Specimen Required: Ear canal swab, Outer ear fluid or swab (Adult and Pediatric)
Referral:
Requisition:
Reference Values:
Negative after 3 days incubation.
For positive samples, a descriptive report will be provided. Mixed cultures of skin or respiratory organisms will be reported as normal flora.
Availability:
Daily
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.