Flexible endoscope reprocessing is an important requirement to minimize the risk of cross-infection between patients due to incomplete disinfection of a bacteria biofilm. The present study introduces a novel opto-chemical treatment to disinfect microbial biofilms (both Gram-positive and Gram-negative bacterial biofilms), commonly found in flexible endoscopes. A low concentration disinfectant combined with infrared and blue light irradiations was applied to disinfect the bacterial biofilms in the endoscope. A basket-integrated optical device was designed to deliver uniform and concentric light onto the channel surface of the endoscope. Colony-forming unit assays were performed to quantify the vial cells while scanning electron microscopy (SEM) illustrated an extracellular matrix (ECM) of the bacterial biofilm. The infrared light irradiation heated the surface of the bacterial biofilm to ~ 65°C. The blue light irradiation induced a relative temperature increase of 30°C on the bacterial biofilm. The results showed that the opto-chemical treatment reduced approximately 7.5-log10 of the bacterial biofilm, which was four times higher than that of a standard disinfectant solution (2% glutaraldehyde). In comparison with the control untreated samples with intact ECMs, the SEM images showed significant damage to the bacterial biofilm under the opto-chemical treatment. The combined treatment induced antimicrobial effects in terms of inhibition of protein synthesis, thermal destruction, and oxidative stress, eradicating the bacterial biofilm more than the standard chemical disinfection. The proposed technique could be an alternative approach to disinfect the microbial biofilms and minimize the risk of secondary infection in endoscopy-related medical facilities.
Flexible cystoscopy is a widely used diagnostic and therapeutic procedure in urology. However, some dangerous bacteria are resistant to traditional antibiotics. Thus, the current study introduced a combination of glutaraldehyde (GTA), 808- nm, and 405-nm laser to disinfect Staphylococcus aureus bacterial biofilms inside flexible cystoscopes based upon a Teflon tubing model. Based upon the pilot study, the samples were exposed either under GTA (0.5% in 180 s), 808-nm (1.6 W/cm2 in 180 s), and 405-nm laser (1.6 W/cm2 in 180 s) alone or their combinations. An infrared (IR) camera was deployed to provide the real-time monitoring of temperature development on the biofilm surface while colony forming unit (CFU) analysis was employed to count viable cells before and after the treatment. The preliminary results showed that GTA, 808-nm, and 405-nm laser alone could induce a 2.2-, 1.4-, and 2-log10 CFU/cm2 reduction of S. aureus bacterial biofilm, respectively. However, their triple combination could eradicate around 6.5-log10 CFU/cm2 reduction in microorganism population. Therefore, the triple combination may be a useful modality for cystoscope reprocessing to prevent any secondary infection in the urinary tract during the cystoscopy.
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