Otitis externa is a common presenting problem in clinical practice. In chronic cases, the infection frequently extends to the middle ear. While multiple factors contribute to otitis development and subsequent secondary infections, the organisms found most often in affected ears include Staphylococcus species, Malassezia pachydermatis, and Pseudomonas aeruginosa.
This is a snippet of a great article produced on the veterinary medicine dvm360 site.
Pseudomanas is becoming very prelevant in all dogs including newfies.