A 17-year longitudinal analysis of microbial shifts and resistance profiles in chronic suppurative otitis media: the modulating role of cholesteatoma

This study aimed to identify evolving microbiological trends and compare pathogen profiles and antibiotic susceptibility patterns in chronic suppurative otitis media (CSOM) based on age and cholesteatoma status over a 17-year period. A retrospective analysis was conducted on 595 ear cultures from CSOM patients managed at a tertiary referral center between 2009 and 2025. Patients were stratified by age (pediatric ≤ 16 vs. adult > 16 years) and the presence or absence of cholesteatoma. Out of 595 samples, 427 pathogen-positive cultures were analyzed. Pseudomonas aeruginosa (29.5%) and Staphylococcus aureus (21.3%) were the predominant isolates. Fungal pathogens, primarily Aspergillus spp., constituted 11.2%. Adults demonstrated a significantly higher culture yield than pediatric patients (84.3% vs. 69.3%; p = 0.002). Aspergillus spp. was significantly more prevalent in non-cholesteatoma cases (13.5% vs. 2.2%; p = 0.001, Fisher’s exact test), whereas Escherichia coli was significantly associated with cholesteatoma (10.8% vs. 4.5%; p = 0.041, Fisher’s exact test). Over time, the point estimate for imipenem resistance in P. aeruginosa was 5.9% in 2009–2014, 0% in 2015–2019, and 33.3% in 2020–2025; comparing the first and last periods yielded a statistically significant difference ( p = 0.021), though wide confidence intervals in earlier years require cautious interpretation. Ciprofloxacin resistance was alarmingly high for both P. aeruginosa (69.6%, n = 78/112) and E. coli (69.2%, n = 18/26). Although P. aeruginosa and S. aureus remain the primary etiologies of CSOM, local resistance dynamics have evolved unfavorably, suggesting that, as indicated by systemic breakpoint testing, standard empirical topical fluoroquinolones may be unreliable as monotherapy. Furthermore, cholesteatoma acts as a distinct pathological modulator that reshapes the microbial microflora. Therapeutic protocols must be dynamically adapted based on regional temporal trends and cholesteatoma status.