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Microbiology of normal external auditory canal
D W Stroman1, P S Roland, J Dohar
1Anti-infective Microbiology, Alcon Research, Ltd., Fort Worth, Texas 76134, USA. David.stroman@alconlabs.com
The Laryngoscope
|January 22, 2002
Summary
This study identified bacteria and fungi in healthy ears, finding Turicella otitidis and Alloiococcus otitidis are common normal otic flora. Antibiotic resistance in Staphylococcus epidermidis was also assessed.
Area of Science:
- Microbiology
- Otolaryngology
- Medical Diagnostics
Background:
- The microbial flora of the healthy human ear canal and cerumen is not fully characterized.
- Understanding normal otic flora is crucial for diagnosing ear infections and interpreting culture results.
Purpose of the Study:
- To isolate and identify bacteria and fungi from the external ear canals and cerumen of healthy individuals.
- To determine the antimicrobial susceptibility profiles of isolated bacterial species.
Main Methods:
- Prospective collection of ear canal and cerumen specimens from healthy subjects.
- Combined phenotypic and genotypic methods for species-level identification of microorganisms.
- Minimal inhibitory concentration (MIC) testing following Clinical Laboratory Standards Institute guidelines.
Main Results:
- A total of 314 organisms from cerumen and 310 from ear canals were isolated.
- Gram-positive bacteria, primarily Staphylococci (63%) and Coryneforms (19-22%), dominated both sample types.
- Turicella otitidis and Alloiococcus otitidis were found at higher frequencies than previously reported.
- Staphylococcus epidermidis exhibited significant resistance to neomycin, oxacillin, and ofloxacin.
Conclusions:
- Turicella otitidis and Alloiococcus otitidis should be considered part of the normal otic flora.
- Corynebacterium auris was isolated from healthy adults, expanding its known host range.
- Findings provide a baseline for normal ear microbiota and inform clinical decision-making regarding antibiotic use.
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