Otitis externa laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Luke Rusowicz-Orazem, B.S.
Overview
Laboratory Findings
Laboratory findings will vary based on the suspected source of otitis externa.
Bacterial
- Otitis externa from a suspected bacterial infection will be determined by the following tests:
- Swab of the ear canal to determine if the infection is caused by Pseudomonas aeruginosa or Staphylococcus aureus.[1]
- This test will be performed in the event that the symptoms do not resolve with the treatment and the otitis externa becomes recurrent.
- Gram stain test: If the cause is determined to be bacterial, the gram-stain test will determine whether the cause is Psuedomonas aeruginosa or Staphylococcus aureus:[2]
- Results are purple: indicates that the culture is gram-positive and is indicative of Staphylococcus aureus.
- Results that are red: indicates that the culture is gram-negative and is indicative of Pseudomonas aeruginosa.
- Real-time polymerase chain reaction to detect and determine the exact bacterial pathogen.[3]
- Results indicative of Pseudomonas aeruginosa or Staphylococcus aureus include DNA samples from either pathogen.[4]
- Swab of the ear canal to determine if the infection is caused by Pseudomonas aeruginosa or Staphylococcus aureus.[1]
Fungal
- Otitis externa from a suspected fungal infection will be determined by the following tests:
- Swab of the ear canal to determine if the infection is caused by Aspergillus niger,Aspergillus fumigatus, or Candida albicans.[5]
- A fungal culture will be collected to cultivate spores for observation, determining the specific pathogenic fungus.
- Immunofluorescent microscopy may reveal the following results:[6]
- Fungal hyphae
- Arthrospores
- Arthroconidia
- Real-time polymerase chain reaction to detect and determine the exact fungal pathogen.[7]
- Results indicative of Aspergillus niger or Candida albicans include DNA samples from either pathogen.
References
- ↑ Llor, C.; McNulty, C. A. M.; Butler, C. C. (2014). "Ordering and interpreting ear swabs in otitis externa". BMJ. 349 (sep01 2): g5259–g5259. doi:10.1136/bmj.g5259. ISSN 1756-1833.
- ↑ Beveridge TJ (2001). "Use of the gram stain in microbiology". Biotech Histochem. 76 (3): 111–8. PMID 11475313.
- ↑ Khan AA, Cerniglia CE (1994). "Detection of Pseudomonas aeruginosa from clinical and environmental samples by amplification of the exotoxin A gene using PCR". Appl. Environ. Microbiol. 60 (10): 3739–45. PMC 201881. PMID 7986047.
- ↑ Brakstad OG, Aasbakk K, Maeland JA (1992). "Detection of Staphylococcus aureus by polymerase chain reaction amplification of the nuc gene". J. Clin. Microbiol. 30 (7): 1654–60. PMC 265359. PMID 1629319.
- ↑ Kaur R, Mittal N, Kakkar M, Aggarwal AK, Mathur MD (2000). "Otomycosis: a clinicomycologic study". Ear Nose Throat J. 79 (8): 606–9. PMID 10969470.
- ↑ "Aspergillus Otomycosis | Aspergillus & Aspergillosis Website".
- ↑ Van Burik JA, Myerson D, Schreckhise RW, Bowden RA (1998). "Panfungal PCR assay for detection of fungal infection in human blood specimens". J. Clin. Microbiol. 36 (5): 1169–75. PMC 104793. PMID 9574670.