Aetiology and pathology 1.Bacteriology: characteristic of the bacteriology of chronic otitis media is a shift towards a predominance of gram negative bacilli, most frequently isolated bacteria include Pseudomonas aeruginosa, staphylococcus, proteus and corynebacteriumAetiology and pathology  1.Bacteriology: characteristic of the bacteriology of chronic otitis media is a shift towards a predominance of gram￾negative bacilli, most frequently isolated bacteria include Pseudomonas aeruginosa, staphylococcus, proteus and corynebacterium