Clinical impact of major pathogenic genotypes of Pseudomonas aeruginosa associated with refractory chronic suppurative otitis media.

Purpose: Chronic suppurative otitis media (CSOM) is characterized by persistent inflammation of the mucous membrane of the middle ear and mastoid. One of the primary causative agents of CSOM is P. aeruginosa, known for its production of virulent toxins and enzymes. Some cases of CSOM, improvement may not occur despite treatment lasting three weeks, leading to what is termed refractory CSOM. This research aims to characterize the P. aeruginosa strains isolated from patients with refractory CSOM in Gyeongsangnam-do, South Korea, providing insights into their pathogenic profiles.
Methods: We conducted a retrospective analysis of P. aeruginosa isolates from the otorrhea of patients diagnosed with CSOM at a tertiary hospital in Gyeongsangnam-do, over a period from January 2005 to August 2022. The strains were examined using multilocus sequence typing (MLST) and toxin gene assay to assess genetic diversity and virulence.
Results: 39 samples were obtained from 13 cases of refractory CSOM and 15 cases of non-refractory CSOM. The findings unveiled that the P. aeruginosa cultured from patients with refractory CSOM belonged to the P. aeruginosa sequence type 235 (ST235) strain, which harbors the exoU gene as a major virulence factor.
Conclusion: The detection of ST235 in refractory CSOM signifies a challenging clinical scenario. Given the genotype's strong virulence and antibiotic resistance, identifying ST235 through MLST can guide effective management approaches, including potential surgical intervention. This study underscores the necessity of broader epidemiological investigations to understand ST235 behavior and advocates for patient education to mitigate the impacts of this formidable pathogen in CSOM.
Competing Interests: Declarations. Ethics approval and consent to participate: This study adhered to the principles outlined in the Declaration of Helsinki. It received approval from the Institutional Review Board (IRB) of Gyeongsang National University Hospital on May 24, 2024, under the IRB approval number [2024-24-006-002]. Due to the retrospective design of the study and the absence of any associated harm to the participants, the IRB waived the need for investigators to obtain signed informed consent forms from the participants. The bacterial strains analyzed were provided by the Fastidious Specialized Pathogen Resources Bank (a member of the National Culture Collection for Pathogens, GNUH, Jinju, Korea), which supplies clinically isolated strains for research purposes under ethical guidelines. Competing interests: The authors declare no competing interests.
(© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)