EVALUATION OF FACTORS WHICH MAY BE OF IMPORTANCE IN THE PRODUCTION OF EXTERNAL EAR INFECTIONS

[摘要] An external ear infection showing morphologic and bacteriologic findings and pathologic changes similar to those observed in humans was produced regularly in cats. Therefore, a series of experiments were designed using cats to evaluate the importance of the following factors in the production of external otitis (1) Infection with Pseudomonas aeruginosa; (2) high temperature; (3) high humidity; (4) removal of lipids and (5) trauma. No single factor produced consistent morphologic and pathologic inflammatory changes of the skin lining of the external ear. It was repeatedly demonstrated that infection with Pseudomonas organisms is a most important factor in the production of external ear disease when combined with trauma and/or lipid removal. High temperature and elevated humidity alone or in combination did not increase the degree of inflammatory changes produced by the other factors. Serial bacteriologic studies failed to reveal a rapid disappearance of Pseudomonas organisms following instillation into the untreated external ear. Positive cultures persisted for long periods and the rate of disappearance could not be correlated with any of the factors tested. Further studies concerning these factors are now in progress.