Special Precautions/Comments:

N.B.  For investigation of fungal infection, scrapings of material from the ear canal are preferred although swabs can also be used.

Interferences:  Antibiotics may affect growth of certain bacteria.

Method:  Culture on selective media. Length of anaerobic culture will be based on provided clinical detail. Isolates will be identified where clear. Where identification is not clear a likely/possible identity will be given until additional tests can be performed to confirm identity. Significant isolates will undergo antibiotic susceptibility testing.  Calibration: N/A.  EQA scheme: NEQAS EQA scheme. IQC: Regular resubmission of anonymised patient samples.

Interpretation: Negative cultures will be reported as No growth. Typical/expected skin flora and mixed coliforms (including mixed coliforms with pseudomonads) will be reported as such, these samples will not receive further identification and testing. Lancefield group B streptococci and Enterococci will be reported as No bacterial pathogens isolated, these samples will not receive further identification and testing. Significant organisms will be identified and tested for antibiotic susceptibility. Please note that yeast and fungal isolates will be identified but are not routinely be tested for antibiotic susceptibility. Where Group A Beta haemolytic Streptococcus species are isolated from in-patient samples, the Consultant Microbiologist will be informed upon identification and clinical comment will be provided where appropriate. Unusual/unexpected results may be sent to a reference laboratory (turnaround 7-10 days).

Additional Information:

Background information: 

Otitis Externa:  In general, infection of the external auditory canal resembles infection of skin and soft tissue elsewhere. However, there are some notable differences. The canal is narrow and, as a result, foreign materials and fluid that enter can become trapped, causing irritation and maceration of the superficial tissues. Otitis externa can be subdivided into categories: acute localised; acute diffuse; chronic; and invasive (‘malignant’). However, except for invasive, they are rarely differentiated as such in clinical practice.

Otitis Media:  Otitis media covers a broad spectrum of disease, which includes acute otitis media and chronic suppurative otitis media, both these conditions are covered in more detail below. Although uncommon in adults, the causative organisms and treatment of otitis media are the same as in children. As uptake of the pneumococcal vaccination has become more widespread the causative organisms for this condition have changed. An external ear swab is not useful in the investigation of otitis media unless there is perforation of the eardrum. Tympanocentesis, to sample middle ear effusion, is rarely justified.

Keywords: Ear, otitis media, otitis externa, candida, aspergillus, pseudomonas