Objectives: Aetiological diagnosis of external or media otitis by aerobic and anaerobic culture with identification and susceptibility test of the isolated organism(s).

Test material: Pus from the external or middle ear.

Collection time: Before start of antibiotic therapy.

Equipment: Cotton wool or dacron swab, test tube with transport medium.

Procedure: 1. Collect a specimen of the discharge on a thin, sterile cotton wool or dacron swab.

2. Place the swab in a container with the transport medium, breaking off the swab stick to allow the stopper to be replaced tightly.

3. Label the specimen and send it to the laboratory.

Storage: Refrigerated (2-8 °C).

Transportation: Preferably in a cooling box (2-8 °C), if delayed for more than one hour.

Reporting: Results can be expected within 48 hours.

Comments: For external ear infections only Staphylococcus aureus, Strepto-coccus pyogenes, Pseudomonas aeruginosa, Vibrio spp. and Aspergillus will be looked for and reported. For middle ear infections only pneumococcus, Streptococcus pyogenes, Haemophilus influenzae and Staphylococcus aureus will be reported with a susceptibility test. For the chronic discharging ear, Bacteroides species and fungi will also be reported in addition to the organisms reported for middle ear infections.

    Cultures of the external auditory canal generally do not reflect the bacteria causing middle ear infection unless there has been a recent rupture of the tympanic membrane. Tympanic membrane aspiration is rarely performed.