A study of acute otitis externa at Wellington Hospital, 2007-2011

Background Acute otitis externa (AOE) is a common inflammatory condition affecting the external ear that occasionally presents with persistent, severe pain, which may be unresponsive to first-line therapy and require assessment and treatment in the hospital setting. Aims To identify the microorganisms responsible for cases of otitis externa presenting to Wellington Hospital, New Zealand, over a five-year period between 2007 and 2011. We also aim to evaluate current management of this condition and to recommend future treatment options. Method A five-year retrospective study, with data obtained from case notes and electronic records for all patients presenting with otitis externa to Wellington Hospital between 2007 and 2011. Results Of 347 cases identified, 144 were included in the study. Pseudomonas aeruginosa (P. aeruginosa) was the most common organism (46.5 per cent), while Staphylococcus aureus (S. aureus) was the second most common (31.9 per cent). Most patients received appropriate topical treatment. However, a significant number were treated with systemic antibiotics alone without adverse outcomes. Conclusion Pseudomonas aeruginosa is the most common microbe causing acute otitis externa in patients that require hospital level management in Wellington, New Zealand. In most cases, patients received appropriate topical therapy; however, it appears a large number received systemic antibiotic therapy without topical treatment. We recommend broad-spectrum topical antimicrobial therapy in all patients with uncomplicated AOE and culture-sensitive topical treatment with consideration of systemic antimicrobials for severe AOE requiring hospital admission.