Otitis Externa in Children: Causes and Risk Factors

Primary Bacterial Pathogens

Pseudomonas aeruginosa is the most frequently isolated organism, accounting for 20-60% of cases in children with otitis externa, according to the American Academy of Otolaryngology-Head and Neck Surgery 1, 2
Staphylococcus aureus is the second most common pathogen, responsible for 10-70% of infections, as reported by the American Academy of Otolaryngology-Head and Neck Surgery 1, 2
Other gram-negative organisms (excluding P. aeruginosa) collectively cause only 2-3% of cases, as found by the American Academy of Otolaryngology-Head and Neck Surgery 1, 2
Methicillin-resistant Staphylococcus aureus (MRSA) should be suspected when otorrhea is recurrent or fails to respond to initial treatment, according to the American Academy of Otolaryngology-Head and Neck Surgery 4

Fungal infections are distinctly uncommon in primary acute otitis externa but may occur after prolonged topical antibiotic therapy, as noted by the American Academy of Otolaryngology-Head and Neck Surgery 1, 2
Aspergillus and Candida species are the primary fungal pathogens when otomycosis does occur, as reported by the Journal of the American College of Radiology 5
Fungal overgrowth is more likely in tropical climates, humid environments, diabetic patients, or immunocompromised children, although the strength of evidence for this is not specified 6

Excessive moisture exposure converts the normal acidic pH of the external auditory canal to an alkaline environment, promoting bacterial growth, as found by the Journal of the American College of Radiology and the American Academy of Otolaryngology-Head and Neck Surgery 1, 5, 7
Water activities are strongly associated with otitis externa, with 44% of visits occurring during summer months (June-August), according to the American Academy of Otolaryngology-Head and Neck Surgery 7, 8
Warm, humid climates increase susceptibility, with the highest incidence in the Southern United States (9.1 per 1000 population), as reported by the American Academy of Otolaryngology-Head and Neck Surgery 7, 8

Children aged 5-14 years account for just under half of all otitis externa visits, as found by the American Academy of Otolaryngology-Head and Neck Surgery 7, 8
The condition is uncommon before age 2 years, with very limited evidence for this age group, according to the American Academy of Otolaryngology-Head and Neck Surgery 1, 7, 8
Lifetime incidence reaches approximately 10% across all ages, as reported by the Journal of the American College of Radiology 5

Otitis externa must be distinguished from acute otitis media in children, as the latter is caused by different organisms (Streptococcus pneumoniae and Hemophilus influenzae) and requires different management, as noted by the Journal of the American College of Radiology and the American Academy of Otolaryngology-Head and Neck Surgery 1, 5, 6