Search

Abstract Background Environmental surface decontamination is a crucial tool to prevent the spread of infections in hospitals. However, manual cleaning and disinfection may be insufficient to eliminate pathogens from contaminated surfaces. Ultraviolet-C (UV-C) irradiation deploying autonomous disinfection devices, i.e. robots, are increasingly advertised to complement standard decontamination procedures with concurrent reduction of time and workload. Although the principle of UV-C based disinfection is proven, little is known about the operational details of UV-C disinfection delivered by robots. To explore the impact of a UV-C disinfection robot in the clinical setting, we investigated its usability and the effectiveness as an add-on to standard environmental cleaning and disinfection. Additionally, its effect on Candida auris, a yeast pathogen resistant to antifungals and disinfectants, was studied. Methods After setting the parameters “surface distance” and “exposure time” for each area as given by the manufacturer, the robot moved autonomously and emitted UV-C irradiation in the waiting areas of two hospital outpatient clinics after routine cleaning and/or disinfection. To quantify the efficacy of the robotic UV-C disinfection, we obtained cultures from defined sampling sites in these areas at baseline, after manual cleaning/disinfection and after the use of the robot. Four different C. auris strains at two concentrations and either in a lag or in a stationary growth phase were placed in these areas and exposed to UV-C disinfection as well. Results The UV-C irradiation significantly reduced the microbial growth on the surfaces after manual cleaning and disinfection. C. auris growth in the lag phase was inhibited by the UV-C irradiation but not in the presence of the rim shadows. The effects on C. auris in the stationary phase were differential, but overall C. auris strains were not effectively killed by the standard UV-C disinfection cycle. Regarding usability, the robot’s interface was not intuitive, requiring advanced technical knowledge or intensive training prior to its use. Additionally, the robot required interventions by the technical operator during the disinfection process, e.g. stopping due to unforeseen minor dislocation of items during the clinical service or due to moving individuals, making it a delicate high-tech device but not yet ready for the autonomous use in the clinical routine. Conclusions Presently, the UV-C robot tested in this study is not ready to be integrated in the environmental cleaning and disinfection procedures in our hospital. The single standard disinfection UV-C irradiation cycle is not sufficient to inactivate pathogens with augmented environmental resilience, e.g. C. auris, particularly when microbial loads are high.

Abstract: Background: Biofilm formation on voice prostheses in laryngectomized patients usually limits the lifetime of the device. The purpose of this study was to compare the biofilm resistance of different valve flaps of modern voice prostheses in an in vitro simulation of an oropharyngeal biofilm. Methods: Growth of biofilm deposits on valve flaps (n = 12) removed from Provox 2, Provox Vega, Provox ActiValve, Blom Singer Advantage, and Phonax voice prostheses was evaluated and compared to medical‐grade silicone (n = 12) in an in vitro biofilm model (22 days) after incubation with a multispecies bacterial‐fungal biofilm composition. Results: The Provox ActiValve and the Blom Singer Advantage prostheses showed significantly less surface biofilm formation than the other prostheses and then silicone. Conclusion: The use of silver oxide and Teflon as valve flap materials proves to reduce long‐term biofilm formation in vitro. The applied model allows rapid screening for novel biofilm‐inhibitive materials and durable coatings designated for more biofilm resistant medical devices. [ABSTRACT FROM AUTHOR]

Objectives/Hypothesis: Recent in vitro models simulating biofilm formation on medical polymers are restricted to only short-term observation periods of 2 hours to 12 days. Study Design: The goal of this study was to develop an in vitro model to generate a long-term polymicrobial biofilm with Candida albicans ( C albicans) and Streptococcus salivarius ( S salivarius) on thermoplastic medical grade silicone (TPS) and polyurethane (TPU) and continuous documentation of growth kinetics. Methods: Test platelets of TPS and TPU were incubated in well plates in RPMI agar at 37°C. Both microbial specimen were isolated from explanted voice prostheses and added every second day for 28 days. Afterward, only the nutrition solution has been changed regularly. Biofilm kinetics were monitored using a specially designed image analysis software to calculate the percentual surface covering of each platelet. Biofilm architecture was investigated by scanning electron microscopy (SEM). Microbial infiltration was examined by crystal violet staining and thin section microscopy. Results: On both materials tested, a cover of living candida biofilm could be generated over 140 days. Colonization was permanent with at least 10% surface coverage. Initially, both materials showed coverage of up to 80% followed by biofilm detachment, which could be reduced by adding planktonic microbes. SEM confirmed three-dimensional biofilm architecture with dimorphic candida growth. Microbial material infiltration of nonhypheal types was proved in 2 TPU platelets, but not in TPS. Conclusions: The in vitro model presented in this study mimics in vivo events of biofilm formation on medical polymers with continuous monitoring of living biofilm kinetics. Laryngoscope, 2013 [ABSTRACT FROM AUTHOR]