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Alloiococcus otitidis--otitis media pathogen or normal bacterial flora?
Krister Tano1, Robert von Essen, P O Eriksson
1Department of Clinical Science, Otorhinolaryngology, Sunderby Hospital, Luleå, Sweden. krister.tano@nll.se
APMIS : Acta Pathologica, Microbiologica, Et Immunologica Scandinavica
|November 26, 2008
Summary
Alloiococcus otitidis was found in healthy ear canals, suggesting it is normal flora, not a pathogen. A rat model showed mild middle ear reactions, questioning its role in otitis media.
Area of Science:
- Microbiology
- Otolaryngology
- Infectious Diseases
Background:
- Alloiococcus otitidis is a potential pathogen in otitis media, frequently found in middle ear effusions.
- Its role as a pathogen remains unclear, necessitating further investigation.
Purpose of the Study:
- To determine the presence of Alloiococcus otitidis in the nasopharynx and outer ear canals.
- To develop a reliable culture method for isolating A. otitidis.
- To assess the pathogenicity of A. otitidis in a rat model of acute otitis media.
Main Methods:
- Investigated nasopharyngeal and outer ear canal samples from children and healthy individuals using PCR and conventional culture.
- Utilized a rat model to evaluate the clinical outcome of A. otitidis middle ear infections.
- Developed a culture method using blood agar plates with 6% saline and specific antisera.
Main Results:
- A. otitidis was detected by PCR in 7% of children's nasopharynxes and 29% of healthy outer ear canals.
- Conventional culture successfully isolated A. otitidis from healthy ear canals but not from nasopharyngeal samples.
- The rat model demonstrated mild middle ear responses, failing to induce purulent acute otitis media.
Conclusions:
- Alloiococcus otitidis appears to be a commensal bacterium in the healthy outer ear canal flora.
- The study questions the pathogenicity of A. otitidis in causing acute otitis media.
- A modified culture method using 6% saline blood agar is effective for isolating A. otitidis from the outer ear canal.
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