Abstract
Four types of investigation of the causes of diffuse otitis externa revealed the following:
1) Bacteriological examinations of 54 patients (54 ears) with diffuse otitis externa with effusion showed 53 strains of bacteria in 47 ears: Staphylococcus aureus in 29 ears (62%), Pseudomonas aeruginosa in 8 ears (17%) and multiple drug resistant Staphylococcus aureus in 2 ears (4%).
These results confirmed the importance of bacteriological examinations.
2) Bacteriological examinations of 7 other patients with unilateral diffuse otitis externa revealed Staphylococcus epidermis in 4 of the 7 normal ears and in only one ear of the infected ears.
In general, Staphylococcus epidermis is thought to play a protective role. These results indicate that removal of Staphylococcus epidermis by excessive cleaning of the external ear canal is not recommended.
3) The incidence of diffuse otitis externa was high in summer and early fall: 46 cases in July, 76 in August, 62 in September and 48 in October.
It was found that scratching of the external ear canal after the onset of the disease may worsen the symptoms.
4) The anterior inferior meatal recess was proved to be deeper in patients with diffuse otitis externa with effusion than in those with simple chronic otitis media with effusion or with otitis externa without effusion.
These findings suggest that deposits of debris and effusion in this recess may be a causative factor in this disease.
It seems that in most cases several factors may be involved in the etiology of diffuse otitis externa, so in order to cure this disease several causative factors must be removed.
