Evaluation of Disinfection Efficacy in Flexible Laryngoscopy According to Cidex Ortho-Phthalaldehyde Immersion Time: A Multicenter Study

Background and Objectives Flexible laryngoscopes are indispensable tools in otolaryngology, but their frequent use makes them vulnerable to contamination, thus posing a risk of cross-infection. Unlike gastrointestinal endoscopes, flexible laryngoscopes currently lack standardized disinfection protocols. This study evaluates the efficacy of Cidex OPA (0.55% ortho-phthalaldehyde) to establish an effective, practical disinfection protocol for flexible laryngoscopes.Materials and Method This multicenter study involved the use of flexible laryngoscopes in otolaryngology outpatient clinics across five university hospitals. Laryngoscopes were immersed in Cidex OPA for 1, 5, or 12 minutes, with an additional group treated using Tristel wipes and foam after a 12-minute immersion. Swab samples were collected from the distal 15 cm of each laryngoscope following disinfection and cultured on blood agar plates under aerobic conditions at 35°C–37°C with 5% CO<sub>2</sub> for 72 hours. Positive controls included laryngoscopes directly contaminated with saliva or laryngeal secretions.Results Six out of ten positive control samples demonstrated bacterial growth. However, no bacterial growth was observed in any sample from the Cidex OPA immersion groups (1, 5, or 12 minutes), including the group treated with Tristel. These findings indicate that even a 1-minute immersion in Cidex OPA effectively eliminates bacterial contamination.Conclusion This study provides evidence supporting an efficient disinfection method that can enhance infection control and streamline clinical workflow. Further research with a larger sample size and varied disinfection techniques is needed to establish comprehensive disinfection guidelines for flexible laryngoscopes.