[Bacterial epidemiology of chronic otitis. Prophylactic and therapeutic deductions].

Antimicrobial sampling was performed in the external auditory canal and in the mastoid cavity when possible in 80 middle ears operated on during the last 15 months. These samplings concerned 20 cholesteatomas. 25 suppurative chronic otitis, 25 non suppurative chronic otitis and 6 miscellaneous. In 20 out of 80 cases (25%), one or several microbial agents were identified: cholesteatomas (35%), suppurative chronic otitis (38%), non suppurative ones (4%) and miscellaneous (16%). In most cases a staphylococcus or a negative gram agent was sensitive to amoxycillin-clavulanique acid. When sampling was performed in the mastoid cavity, the agent was not sensitive to this antibiotic (80% of cases). This study demonstrates that a prophylactic therapy against aerobic and anaerobic agents is necessary in non suppurative chronic otitis whereas the antimicrobial therapy must be adapted in other pathologies.