Microbiological Profile and Recorded Antimicrobial Susceptibility Findings in Patients with Refractory Chronic Suppurative Otitis Media: A Retrospective Study

Background: To evaluate the distribution of bacterial microorganisms isolated from ear cultures and to describe the recorded antimicrobial susceptibility and resistance findings in patients with refractory chronic suppurative otitis media (CSOM) and persistent otorrhea.
Materials and Methods: This retrospective study included patients with CSOM treated at a tertiary care university hospital between January 2021 and December 2023. Refractory CSOM was defined as persistent active otorrhea despite two consecutive standardized 14-day courses of medical treatment. Ear cultures were obtained seven days after completion of the last antibiotic course. Microorganisms were identified using conventional microbiological methods and the VITEK® system. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method and interpreted according to EUCAST criteria. Because the number of isolates tested against each individual antibiotic was unavailable, antimicrobial findings were summarized as frequencies of recorded susceptible and resistant results.
Results: A total of 185 patients were evaluated. Nineteen patients with negative cultures and 15 patients with fungal growth were excluded, leaving 151 patients with bacterial growth for the final analysis. The mean age was 33.4 ± 21.4 years, and 99 patients  (65.6%) were female. The predominant bacterial isolates were Pseudomonas aeruginosa  (n=92; 60.9%) and Staphylococcus aureus  (n=36; 23.8%). Meropenem  (n=72) and amikacin  (n=63) were the most frequently documented agents among the recorded susceptible results. Ciprofloxacin  (n=49), erythromycin  (n=47), and tetracycline  (n=44) were the most frequently documented agents among the recorded resistant results. Conclusions: Pseudomonas aeruginosa and Staphylococcus aureus were the predominant bacterial isolates in patients with refractory CSOM. Because antibiotic-specific testing denominators were unavailable, the antimicrobial findings should be interpreted as descriptive frequencies rather than isolate-specific susceptibility or resistance rates. Microbiological evaluation may help identify the causative organism and inform subsequent management in patients with persistent otorrhea after standardized medical treatment.