The most common causative organism for external otitis in adults is:: (A) Streptococcus viridans, (B) Staphylococcus epidermidis, (C) Pseudomonas aeruginosa, (D) E. coli
Answer is C. Otitis externa is an inflammatory and infectious process of the external auditory canal. Pseudomonas aeruginosa and Staphylococcus aureus are the most commonly isolated organisms. Less commonly isolated organisms include Proteus species, Staphylococcus epidermidis, diphtheroids, and Escherichia coli.