ABSTRACT
Chronic Otitis Media [COM] remains one of the most common childhood chronic infectious diseases worldwide. This study was carried out to determine the organisms inducing COM and their drug resistance patterns in Zanjan. This cluster cross-sectional study was conducted on 100 patients suffering from COM in the age range of 18-45. COM specimens were obtained in operating room and then cultured on 4 different media. Following the diagnostic tests and identifying the bacteria, their susceptibility to antibiotics was assessed. The most common isolated bacteria were Pseudomonas aeruginosa [24.7%], Staph ylococcus aureus [17.6%] and Proteus spp [15.2%]. The results of bioassay tests for isolated bacteria were as follows: Pseudomonas aeruginosa had the highest resistance to cefixime and co-trimoxazol [100%]. The highest resistance of Staphylococcus Aureus was to co-trimoxazol [70%] and cefixime [50%]. Regarding the multi-bacterial etiology of COM and high prevalence of antibiotic resistance, identification of causative bacteria and bioassay test prior to any therapeutic procedure seams necessary