The Possible Role of Biofilm Formation in Recidivism of Cholesteatomatous and Noncholesteatomatous Chronic Suppurative Otitis Media.

Objective: Chronic suppurative otitis media (CSOM) is typically classified into two distinct types: CSOM (without cholestetoma) and CSOM with cholesteatoma (CCSOM). The main microbial agents in both types are Pseudomonas aeruginosa, Staphylococcus aureus, and Klebsiella pneumoniae. It is believed that the virulence of the infecting microorganisms and their biofilm production capacity play a role in the chronicity and persistence of the disease. The aim of this study was to investigate the pathogen microorganisms with their biofilm formation in CSOM, CCSOM, and their recidivism.

Materials and methods: A cohort of 57 patients was separated into four subgroups as primary CSOM (CSOM, CCSOM) and postoperatively recurring/residual CSOM [(R)CSOM, (R)CCSOM] groups. A control group was formed of 10 patients who underwent tympanotomy for conductive hearing loss without any known past/present ear inflammation. In all 67 patients, ear swabs for culture and the tissue samples for biofilm studies were obtained pre- or intraoperatively.

Results: The most common bacteria grown in the culture mediums were Pseudomonas spp., S. aureus, coagulase-negative Staphylococcus, and coliform bacteria. In the SEM study, biofilms were detected in 9 of 15 CCSOM and 6 of 14 CSOM, and in 13 of 14 (R)CCSOM and 11 of 14 (R)CSOM ears. Statistical analysis showed significantly higher rates of biofilm formation in both recidivist cholesteatomatous and noncholesteatomatous CSOM groups than their primary counterpart groups.

Conclusion: The findings that biofilm is more prevalent in the recidivist cases substantiated that biofilm formation is correlated with the persistence and additionally aggressiveness of the disease in both CSOM types. S. aureus appeared as the leading biofilm-producing bacterium.