Investigation of bacterial agents prevalence and their antibiotic susceptibility pattern in acute diffuse otitis externa in Semnan (2000-2003)Investigation of bacterial agents prevalence and their antibiotic susceptibility pattern in acute diffuse otitis externa in Semnan (2000-2003)

Introduction: Acute diffuse otitis externa is one of the most common type of the otitis externa, also known as “Swimmers ear”. In most cases bacterial agents are pathogens associated with this infection. P. aeruginosa and S. aureus are most common bacterial agents. In creasing antimicrobial resistance to many antibiotics , adds to the challeng of optimizing empric treatment for complicated otitis externa. The subject of this study is to determine the bacteriology of acute otitis externa and the susceptibility profiles of isolated bacteria to selected antibiotics. Materials and Methods: External ear canal discharg swabs, collected from 70 acute otitis externa were inculated (at 35ºC for 14 hrs) in thiologycolat broth, sheep blood and mac conkyagar. All isolates recovered were identified to species level by grams staning and biochemical media. Antibiotic susceptibility test has been done using Kirby-bauer method. Resultes: 89.2% of patients were women. 73 bacterial agents were isolated from 70 samples. P. aeruginosa and S. aureus were the most common recovered organism. 94.5% of isolated bacterial agents were susceptible to Ciprofloxacin and 89% to Gentamycin. The least antibiotic susceptibility was to Amoxicillin (5.5%), Cloxacillin (10.9%) and Ampicillin (15.7%). Conclusion: Our study showed that prevalence of acute diffuse otitis externa is higher in female sex (89.2%) and was seen in ages of 20-29 years. About 90% of isolated bactrial agents were susceptible to both Amoxicilin and Gentamycin. Findings (sex and age of infection) of this study were different from those of similar study. The underling causes of observed contraversy were discussed.