en Anti-microbial agents, resistance and treatment protocols Anti-microbial agents, resistance and treatment protocols Original article Original article <strong>Introduction:</strong> Chronic suppurative otitis media (CSOM) is one of the most common middle ear infections leading to extra and intracranial complications if not diagnosed promptly. Early identification and detection of the etiological agents and antibiotic susceptibility patterns assist in preventing complications. <strong>Methods:</strong> Two hundred twelve ear swabs were collected using sterile cotton swabs. Direct gram staining was done and then inoculated into blood, MacConkey, and Nutrient agar. Bacterial isolates were identified using conventional methods. According to CLSI guidelines, Antibiotic susceptibility testing was performed by Kirby-Bauer disc diffusion method. Minimum inhibitory concentration (MIC) was performed by the agar dilution method. Extended-spectrum beta-lactamases producing bacteria were detected by the phenotypic confirmatory test and then corroborated by uniplex PCR. <strong>Results:</strong> Out of 212 samples, 157 samples (74.06%) were culture-positive for bacteria. The isolated bacteria included <em>Pseudomonas aeruginosa</em> (46.24%), <em>Staphylococcus aureus</em> (26.59%), <em>Klebsiella pneumoniae</em> (14.45%), coagulase-negative <em>Staphylococcus aureus</em> (5.20%), <em>Proteus mirabilis</em> (4.05%), <em>Enterococcus faecalis</em> (2.89%), and <em>Escherichia coli</em> (0.58%). The <em>P. aeruginosa</em> isolates showed 96.25% and 95% susceptibility to amikacin and ofloxacin, respectively. All Gram-negative bacilli isolates were 100% sensitivite to imipenem. Ten (30.30%) isolates were ESBL producers with the <em>CTX-M-14</em> gene detected in most of them. <strong>Conclusion:</strong> Our study found that <em>P. aeruginosa</em> was the most common isolated pathogen bacteria. Knowledge of CSOM causing bacteria and their susceptibility to antibiotics would help choose an appropriate treatment, thereby preventing antibiotic resistance and complications in these cases. Chronic suppurative otitis media (CSOM), Minimum Inhibitory Concentration, ESBL, Uniplex PCR 196 202 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-346-1&slc_lang=en&sid=1 A.V. Kavitha kaviavk@gmail.com 0000-0002-1465-1109 No Department of Microbiology, Government Kilpauk Medical College, Chennai, Tamilnadu, India Radhika Katragadda radhikatra@gmail.com 0000-0002-6756-7306 No Department of Microbiology, Government Kilpauk Medical College, Chennai, Tamilnadu, India Leela Vajravelu dr.k.v.leela@gmail.com 0000-0003-3288-1335 No Department of Microbiology, Government Kilpauk Medical College, Chennai, Tamilnadu, India Thyagarajan Ravinder drtravinder67@gmail.com 0000-0002-5602-5245 Yes Department of Microbiology, Government Kilpauk Medical College, Chennai, Tamilnadu, India