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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.

Biofilms have developed various mechanisms to protect themselves from external influences and antibiotics. Next steps might seek to exploit recent successes in biofilm research to develop next-generation antibiotics, to better simulate in vitro the effects of antibiotics on bacteria and biofilms under laboratory conditions. CORR Insights®: Halicin Is Effective Against Staphylococcus aureus Biofilms In Vitro. [Extracted from the article]

Infections related to orthopedic procedures are considered particularly severe when implantation materials are used, because effective treatments for biofilm removal are lacking. In this study, the relatively new approach for infection control by using an erbium:yttrium‐aluminum‐garnet (Er:YAG) laser was tested. This laser vaporizes all water containing cells in a very effective, precise, and predictable manner and results in only minimal thermal damage. For preliminary testing, 42 steel plates and 42 pins were seeded with mixed cultures. First, the minimally necessary laser energy for biofilm removal was determined. Subsequently, the effectiveness of biofilm removal with the Er:YAG laser and the cleansing of the metal implants with octenidine‐soaked gauze was compared. Then, we compared the effectiveness of biofilm removal on 207 steel pins from 41 patients directly after explantation. Sonication and scanning electron microscopy were used for analysis. Laser fluences exceeding 2.8 J/cm2 caused a complete extinction of all living cells by a single‐laser impulse. Cleansing with octenidine‐soaked gauze and irradiation with the Er:YAG laser are both thoroughly effective when applied to seeded pins. In contrast, when explanted pins with fully developed biofilms were analyzed, we found a significant advantage of the laser procedure. The Er:YAG laser offers a secure, complete, and nontoxic eradication of all kinds of pathogens from metal implants without damaging the implant and without the possible development of resistance. The precise noncontact removal of adjacent tissue is a decisive advantage over conventional disinfectants. Therefore, laser irradiation could become a valuable method in every debridement, antibiotics, and implant retention procedure. [ABSTRACT FROM AUTHOR]

The antibacterial efficacy of hydrogen peroxide encapsulated in micelles (mH2O2) against biofilms was compared with that of hydrogen peroxide alone and of three commercially available aqueous biocides. The activity of mH2O2 on 24-h biofilms of reference strains of Staphylococcus spp. and Pseudomonas aeruginosa was tested in a static microtiter plate model. The biofilms were incubated with mH2O2 (17% v/v H2O2, 2% lactic acid, 0.3% phytoextract, H2O) and its individual ingredients and compared with three aqueous biocides at different concentrations and times of exposure. After 5-min exposure, 10% mH2O2 (corresponding to 1.7% v/v H2O2) achieved > 8 log10 reductions against all the test strains, while 1.7% H2O2 achieved a maximum of 1.5 log10 reduction. After 5-min exposure, none of the commercially available biocides tested showed themselves to be capable of completely eliminating the test strains embedded in biofilms. Hydrogen peroxide encapsulated in micelles demonstrated enhanced activity against planktonic cells and biofilms of Staphylococcus spp. and P. aeruginosa. [ABSTRACT FROM AUTHOR]

Staphylococcus lugdunensis is an emerging high-virulent pathogen causative of hospital-acquired infections. Biofilm formation is a complex pathogenic process that leads to well-established bacterial communities. There is a paucity of data on the composition of the biofilm matrix among S. lugdunensis strains. Here, twenty-two S. lugdunensis clinical isolates, mainly from orthopaedic infections but also from other clinical sources, were sub-grouped by ribotyping and dendrogram analysis. Biofilms were analysed by fluorimetric methods based on FITC-Wheat Germ Agglutinin, SYPRO Ruby and TOTO-1 dyes to detect exopolysaccharides, proteins and extracellular DNA (eDNA), respectively. Biofilm morphology was investigated under confocal laser scanning microscopy (CLSM). Isolates displayed intriguing diversities in biofilm mass and matrix composition. The content of exopolysaccharides was found to be to be strongly associated with the biofilm mass (R2 = 0.882), while the content of proteins turned out to be weakly (R2 = 0.465) and that of eDNA very weakly associated (R2 = 0.202) to the biofilm mass. [ABSTRACT FROM AUTHOR]

Aims. Microbial colonization of silicone voice prostheses by bacteria and Candida species limits the device lifetime of modern voice prostheses in laryngectomized patients. Thus, research focuses on biofilm inhibitive properties of novel materials, coatings, and surface enhancements. Goal of this in vitro study was the evaluation of seven commonly used growth media to simulate growth of mixed oropharyngeal species as mesoscale biofilms on prosthetic silicone for future research purposes. Methods and Results. Yeast Peptone Dextrose medium (YPD), Yeast Nitrogen Base medium (YNB), M199 medium, Spider medium, RPMI 1640 medium, Tryptic Soy Broth (TSB), and Fetal Bovine Serum (FBS) were used to culture combined mixed Candida strains and mixed bacterial-fungal compositions on silicone over the period of 22 days. The biofilm surface spread and the microscopic growth showed variations from in vivo biofilms depending on the microbial composition and growth medium. Conclusion. YPD and FBS prove to support continuous in vitro growth of mixed bacterial-fungal oropharyngeal biofilms deposits over weeks as needed for longterm in vitro testing with oropharyngeal biofilm compositions. Significance and Impact of Study. The study provides data on culture conditions for mixed multispecies biofilm compositions that can be used for future prosthesis designs. [ABSTRACT FROM AUTHOR]

In a retrospective study the association of the production of extracellular DNA (eDNA) in biofilms of clinical staphylococcal isolates from 60 patients with prosthetic joint infection (PJI) and the clinical outcome were investigated. Data from a previous study on eDNA production determined in 24-hour biofilms of staphylococcal isolates (Staphylococcus aureus n=30, Staphylococcus epidermidis n=30) was correlated with the patients’ clinical outcome after 3 and 12 months. Statistical analysis was performed using either the Spearman’s rank correlations test or the t-test. eDNA production of S. epidermidis in 24-hour biofilms correlated with the patients’ outcome ‘not cured‘ after 12 months. For S. aureus no such correlation was detected. Thus, eDNA may be a virulence factor of S. epidermidis. Quantification of eDNA production as a surrogate marker for biofilm formation might be a potential predictive marker for the management of PJI. [ABSTRACT FROM AUTHOR]

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]

Objectives/Hypothesis: Voice rehabilitation with voice prostheses is a standard therapy in laryngectomized patients. Biofilm formation on the surface of the voice prostheses causes device failure and requires frequent replacements. Studies analyzing the biofilm of voice prostheses have mainly focused on aerobic bacteria. Anaerobic bacteria as an integral part of the biofilms on voice prostheses have not been investigated yet. Study Design: Prospective pilot study on the occurrence of anaerobic and microaerophilic pathogens in biofilm formation on voice prostheses. Methods: Biofilm samples of 15 voice prostheses were analyzed using a polymerase chain reaction-based hybridization method regarding the presence of 11 selected anaerobic and microaerophilic pathogens. Results: In 80% of the voice prostheses, at least one and up to 10 of the tested bacteria could be identified. Fusobacterium nucleatum was the pathogen most often present (73%). Other frequently occurring pathogens were Treponema denticola (40%), Tannerella forsythia (33%), and Eikenella corrodens (33%). There was no correlation between the number of identified bacteria and the indwelling times (mean, 127 days; maximum, 344 days; minimum, 22 days). Conclusions: For the first time, anaerobic and microaerophilic pathogens have been identified as part of the biofilm formation on the surface of voice prostheses. Those pathogens might be responsible for accelerated biofilm formation and reduced lifetime of the voice prostheses. [ABSTRACT FROM AUTHOR]