(0913) Comparative Analysis of the Microbiome in Patients With Cholesteatomatous and Noncholesteatomatous Chronic Otitis Media

Introduction: : Chronic otitis media (COM) is a disease that causes irreversible damage to the middle ear. It could be classified into two groups: cholesteatomatous and non-cholesteatomatous (CCOM & NCOM respectively). A pathophysiological basis related to the microorganisms that colonize the middle ear has been proposed; however, there are insufficient studies to define the role of middle ear microbiota in these diseases. We conducted a retrospective study collecting microbiological culture results from patients with COM, describing the characteristics of both groups.

Methods: A retrospective study was carried out, reviewing otologic surgeries performed at our institution from February to December 2023; including patients with CCOM and NCOM who underwent surgery and had a microbiological sample taken during the procedure. Patient demographic data, comorbidities, diagnosis, and results of cultures were collected.

Results: A total of 24 patients were included, 11 in the CCOM group and 13 in the NCOM group. Of them, 70% had no comorbidities. The mean age at diagnosis was 53 years, and 74% were female. A history of otorrhea at some point during the disease was reported by 91.6% of patients. The highest proportion of transoperative bleeding occurred in the CCOM group. In the CCOM group, 63.64% resulted in some microbiological isolation; in the NCOM group, only 30.76% yielded positive cultures. From the CCOM group, some of the microorganisms isolated were Staphylococcus spp., P. mirabilis, E. faecalis, B. pyogenes, C. albicans, and C. parapsilosis. In contrast, in the NCOM group, Staphylococcus spp. and Candida spp. were isolated.

Conclusions: The proportion of microbiological isolations was notably higher in the CCOM group, with 63.64% of the samples with isolation versus 30.76% in the NCOM group. Regarding the isolated microorganisms, there was a greater diversity of microorganisms in the CCOM group, with gram-positive cocci, enterobacteria, anaerobes, and yeast fungi. This opens new pathways for research into the pathophysiology of COM, with ongoing studies in our institution.