Effect of simethicone on the bactericidal efficacy of a high-level disinfectant

<b>Introduction.</b> Simethicone is an over-the-counter product that is frequently used by clinicians during endoscopic procedures to reduce foaming and improve visualization. Published studies have found simethicone residue on endoscopes after cleaning and disinfecting the devices as per the manufacturer's instructions. Some literature suggests that simethicone residue may reduce disinfection efficacy and increase the risk of patient infections.<b>Gap Statement.</b> However, there appears to be a lack of direct evidence in the literature to either disprove this or correlate simethicone presence with an increased microbial risk.<b>Aim</b>: Research was conducted to evaluate the <i>in vitro</i> impact of simethicone on disinfection efficacy.<b>Methodology.</b> Bacteria were grown in a microtitre plate assay in the presence of a range of simethicone concentrations and then treated with a disinfectant. Bacterial growth was assessed by spotting each microtitre well onto an agar plate.<b>Results.</b> The results demonstrated that, under the conditions tested, simethicone did not reduce the efficacy of Cidex ortho-phthalaldehyde disinfectant, which demonstrated at least a 6-log unit reduction in bacterial viability. Additional experiments showed that direct exposure to 66 mg ml^-1 of simethicone reduced bacterial viability.<b>Conclusion.</b> These results indicate that simethicone may not reduce the bactericidal efficacy of disinfectant during reprocessing, under certain conditions.