Microbial Colonization and Degradation of Rubber Materials in Water Transportation Systems

In wasserführenden Systemen wie Trink- und Abwassertransportleitungen werden Gummi-Dichtungen als zentrales Bauelement eingesetzt. Bezüglich der chemischen und mikrobiellen Beständigkeit sind diese Dichtungsmaterien eine Schwachstelle in den Rohrleitungssystemen. Dies ist darauf zurückzuführen, dass Gummi ein Naturstoff bzw. in seiner synthetischen Form ein naturverwandtes Material ist. Solche Materialien sind potenziell anfällig für mikrobielle Besiedlung und Materialzerstörung. Um zu untersuchen, ob synthetische Gummimaterialien mikrobiell besiedelt und zerstört werden können, wurden verschiedene praxisrelevante Laborversuche entwickelt und durchgeführt. Als Testmaterialien kamen dabei Gummimaterialien dreier Industrieunternehmen zum Einsatz, die zur Herstellung von Dichtungen für Trink- und Abwassertransportsystemen eingesetzt werden. Es wurden Oberflächenbewuchs- und Hemmstoffversuche sowie Anheftungsversuche durch geführt. Die Visualisierung angehefteter Zellen erfolgte mittels Atomic Force Microscopy (AFM = Rasterkraftmikroskopie) und Fluoreszenzmikroskopie. Es wurden Wachstumsversuche mit Gummi als einziger Energie- und Kohlenstoffquelle durchgeführt und von den mit Gummi angezüchteten Bakterien Fettsäurespektren aufgenommen. Außerdem erfolgten Abbauversuche mit den verschiedenen Gummimaterialien Die Resultate dieser Untersuchungen sind nachfolgend zusammengefasst: - Gummi abbauende Mikroorganismen können quantitativ an verschiedene praxisrelevante Gummimaterialien anheften. Zum ersten Mal konnten Gummi abbauende Mikroorganismen (Gordonia westfalica, Gordonia polyisoprenivorans) mit dem AFM visualisiert werden, die an verschiedene Gummimaterialien angeheftet waren. - Es wurde nachgewiesen, dass verschiedene Mikroorganismen mit Gummi als einziger Energie- und Kohlenstoffquelle wachsen können und hierbei typische Wachstumsverläufe mit logarithmischer Wachstumsphase, Plateauphase sowie Absterbephase zeigen. - Erstmals wurde eine DGGE-basierte molekularbiologische Kulturkontrolle artifizieller Bakterienkonsortien aus vier Mikrooganismenspezies während des Gummiabbaus mit Gummi als einziger Energie- und Kohlenstoffquelle etabliert - Von dem Gummi abbauenden Bakterium Gordonia polyisoprenivorans wurden zum ersten Mal Fettsäurespektren während des Wachstums mit synthetischem Gummi als einziger Energie- und Kohlenstoffquelle aufgenommen. Dieses Spektrum unterschied sich signifikant von Spektren, die von Bakterienkulturen aufgenommen wurden, die mit einer leicht verfügbaren Kohlenstoff- und Energiequelle wie Glukose angezüchtet worden sind. Diese Resultate zeigen, dass sich der mikrobielle Stoffwechsel an die Anforderungen des Gummiabbaus adaptieren konnte. - Erstmals konnte mikrobieller Abbau von vulkanisierten, synthetischen Gummimaterialien mit praxisrelevanten Testmaterialien nachgewiesen werden. Es wurden statistisch signifikante Gewichtsreduktionen innerhalb von 3 Monaten von bis zu 10 % nachgewiesen. Die Abbauraten sind organismen- und materialabhängig deutlich unterschiedlich. Die Ergebnisse zeigen, dass Bakterien aus der Familie der Actinomyceten z. B. Gordonia polyisoprenivorans aber auch der bekannte Infektionserreger Pseudomonas aeruginosa und der Schimmelpilze Aspergillus tamarii synthetische Gummimaterialien wie EPDM und SBR abbauen können. - Es wurde außerdem aus Trinkwasser mit Gummi als einziger Energie- und Kohlenstoffquelle das human-pathohene Bakterium Roseomonas mucosa isoliert

Investigations of solutions of Einstein's field equations close to lambda-Taub-NUT

We present investigations of a class of solutions of Einstein's field equations close to the family of lambda-Taub-NUT spacetimes. The studies are done using a numerical code introduced by the author elsewhere. One of the main technical complication is due to the S3-topology of the Cauchy surfaces. Complementing these numerical results with heuristic arguments, we are able to yield some first insights into the strong cosmic censorship issue and the conjectures by Belinskii, Khalatnikov, and Lifschitz in this class of spacetimes. In particular, the current investigations suggest that strong cosmic censorship holds in this class. We further identify open issues in our current approach and point to future research projects.Comment: 24 pages, 12 figures, uses psfrag and hyperref; replaced with published version, only minor corrections of typos and reference

Phenotypes associated with pathogenicity

Around 85% of the environments on Earth are permanently or seasonally colder than 5 °C. Among those, the poles constitute unique biomes, which harbor a broad variety of microbial life, including an abundance of fungi. Many fungi have an outstanding ability to withstand extreme conditions and play vital ecosystem roles of decomposers as well as obligate or facultative symbionts of many other organisms. Due to their dispersal capabilities, microorganisms from cryosphere samples can be distributed around the world. Such dispersal involves both species with undefined pathogenicity and potentially pathogenic strains. Here we describe the isolation of fungal species from pristine Arctic locations in Greenland and Svalbard and the testing of the expression of characteristics usually associated with pathogenic species, such as growth at 37 °C, hemolytic ability, and susceptibility to antifungal agents. A total of 320 fungal isolates were obtained, and 24 of the most abundant and representative species were further analyzed. Species known as emerging pathogens, like Aureobasidium melanogenum, Naganishia albida, and Rhodotorula mucilaginosa, were able to grow at 37 °C, showed beta-hemolytic activity, and were intrinsically resistant to commonly used antifungals such as azoles and echinocandins. Antifungal resistance screening revealed a low susceptibility to voriconazole in N. albida and Penicillium spp. and to fluconazole in Glaciozyma watsonii and Glaciozyma-related taxon

Decolonization potential of 0.02% polyhexanide irrigation solution in urethral catheters under practice-like in vitro conditions

Abstract Background Long-term use of indwelling urethral catheters is associated with high risk of urinary tract infection (UTI) and blockage, which may in turn cause significant morbidity and reduce the life of the catheter. A 0.02% polyhexanide irrigation solution has been developed for routine mechanical rinsing together with bacterial decolonization of suprapubic and indwelling urethral catheters. Methods Using a practice-like in vitro assay and standard silicon catheters, artificially contaminated with clinically relevant bacteria, experiments were carried out to evaluate the bacterial decolonization potential of polyhexanide vs. 1) no intervention (standard approach) and 2) irrigation with a saline (NaCl 0.9%) solution. Swabbing and irrigation was used to extract the bacteria. Results Irrigation with polyhexanide reduced the microbial population vs. the control catheters by a factor of 1.64 log10 (swab extraction) and by a factor of 2.56 log10 (membrane filtration). The difference in mean microbial counts between the two groups (0.90) was statistically significant in favor of polyhexanide when the liquid extraction method was used (p = 0.034). The difference between the two groups using the swab extraction method did not reach statistical significance. Conclusions The saline and polyhexanide solutions are able to reduce bacterial load of catheters, which shows a combined mechanical and antimicrobial effect. Further research is required to evaluate the long-term tolerability and efficacy of polyhexanide in clinical practice

Virucidal efficacy of a sonicated hydrogen peroxide system (trophon EPR) following European and German test methods.

The virucidal efficacy of an automated ultrasound probe disinfector (trophon® EPR) was evaluated in a three step procedure according to European and German test methods. This system uses sonicated hydrogen peroxide mist (35%) at elevated temperature (50°C) in a closed chamber with control of all parameters within a 7 minute cycle. Methods: In the first step of examination, the peroxide solution was tested in a quantitative suspension assay according to the Guideline of Deutsche Vereinigung zur Bekämpfung der Viruskrankheiten (DVV) e.V. and Robert Koch-Institute (RKI) and in parallel with the European Norm EN 14476 with all test viruses creating a virucidal claim. In the second step, the virucidal efficacy of the hydrogen peroxide solution was evaluated in a hard surface carrier test according to the Guideline of DVV with adenovirus, murine norovirus and parvovirus simulating practical conditions. Finally, the efficacy was evaluated by the automated system using stainless steel carriers inoculated with test virus and positioned at different levels inside the chamber

Virucidal efficacy of peracetic acid for instrument disinfection

Abstract Background Various peracetic-acid (PAA)-based products for processing flexible endoscopes on the market are often based on a two-component system including a cleaning step before the addition of PAA as disinfectant. The peracetic acid concentrations in these formulations from different manufacturers are ranging from 400 to 1500 ppm (part per million). These products are used at temperatures between 20 °C and 37 °C. Since information on the virus-inactivating properties of peracetic acid at different concentrations and temperature is missing, it was the aim of the study to evaluate peracetic acid solutions against test viruses using the quantitative suspension test, EN 14476. In addition, further studies were performed with the recently established European pre norm (prEN 17111:2017) describing a carrier assay for simulating practical conditions using frosted glass. Methods In the first step of examination, different PAA solutions between 400 and 1500 ppm were tested at 20 °C, 25 °C, and 35 °C with three test viruses (adenovirus, murine norovirus and poliovirus) necessary for creating a virucidal action according to the European Norm, EN 14476. A second step for simulating practical conditions based on prEN 17111:2017 followed by spreading a test virus together with soil load onto a glass carrier which was immerged into a peracetic acid solution. A fixed exposure time of five minutes was used in all experiments. Results In the quantitative suspension test 1500 ppm PAA solution was needed at 35 °C for five minutes for the inactivation of poliovirus, whereas only 400 ppm at 20 °C for adeno- and murine norovirus were necessary. In the carrier assay 400 ppm peracetic acid at 20 °C were sufficient for adenovirus inactivation, whereas 600 ppm PAA were needed at 25 °C and 35 °C and 1000 ppm at 20 °C for murine norovirus. A PAA solution with 1000 ppm at 35 °C was required for complete inactivation of poliovirus. However, a dramatically decrease of titer after the drying and immerging could be observed. In consequence, a four log reduction of poliovirus titer could not be achieved in the carrier test. Conclusion In summary, 1500 ppm PAA at 35 °C was necessary for a virucidal action in the quantitative suspension test. After passing the requirements of the suspension test, additional examinations with adeno- and murine norovirus on glass carriers based on prEN 17111:2017 will not additionally contribute to the final claim of an instrument disinfectant for virucidal efficacy. This is due to the great stability of poliovirus in the preceded quantitative suspension test and the fact that poliovirus could not serve as test virus in the following carrier assay

Development and virucidal activity of a novel alcohol-based hand disinfectant supplemented with urea and citric acid.

Hand disinfectants are important for the prevention of virus transmission in the health care system and environment. The development of broad antiviral spectrum hand disinfectants with activity against enveloped and non-enveloped viruses is limited due to a small number of permissible active ingredients able to inactivate viruses

A new topical panthenol-containing emollient: Results from two randomized controlled studies assessing its skin moisturization and barrier restoration potential, and the effect on skin microflora

Purpose: Two randomized, intra-individual comparison studies were performed in healthy subjects to evaluate the skin moisturization and barrier restoration potential of a new topical panthenol-containing emollient (NTP-CE) (Study 1), and its effect on skin microflora (Study 2). Methods: In Study 1 (N = 23), two skin areas, one challenged with 0.5% sodium dodecyl sulfate (SDS) solution and one unchallenged, were treated with NTP-CE for 3 weeks. Transepidermal water loss (TEWL), skin hydration, and intercellular lipid lamellae (ICLL) organization were measured at regular intervals during the study. In Study 2 (N = 20), quantitative bacterial cultures were obtained over 6 h from a skin area undergoing wash stress with 10% SDS with subsequent single application of NTP-CE. Results: In Study 1, mean AUC for TEWL reduction from baseline was more pronounced with NTP-CE compared with control (−168.36 vs. −123.38 g/m2/h, p = 0.023). NTP-CE use was also associated with statistically significant improvements in stratum corneum hydration and an increase in mean ICLL length from baseline (day 22: 120.61 vs. 35.85 nm/1000 nm2, p < 0.001). In Study 2, NTP-CE use had no negative impact on bacterial viability. Conclusions: NTP-CE use has favorable and lasting effects on barrier function and repair as well as skin hydration without negatively influencing bacterial viability

A realistic transfer method reveals low risk of SARS-CoV-2 transmission via contaminated euro coins and banknotes

The current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has created a significant threat to global health. While respiratory aerosols or droplets are considered as the main route of human-to-human transmission, secretions expelled by infected individuals can also contaminate surfaces and objects, potentially creating the risk of fomite-based transmission. Consequently, frequently touched objects such as paper currency and coins have been suspected as potential transmission vehicle. To assess the risk of SARS-CoV-2 transmission by banknotes and coins, we examined the stability of SARS-CoV-2 and bovine coronavirus, as surrogate with lower biosafety restrictions, on these different means of payment and developed a touch transfer method to examine transfer efficiency from contaminated surfaces to fingertips. Although we observed prolonged virus stability, our results indicate that transmission of SARS-CoV-2 via contaminated coins and banknotes is unlikely and requires high viral loads and a timely order of specific events

A realistic transfer method reveals low risk of SARS-CoV-2 transmission via contaminated euro coins and banknotes

The current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has created a significant threat to global health. While respiratory aerosols or droplets are considered as the main route of human-to-human transmission, secretions expelled by infected individuals can also contaminate surfaces and objects, potentially creating the risk of fomite-based transmission. Consequently, frequently touched objects such as paper currency and coins have been suspected as potential transmission vehicle. To assess the risk of SARS-CoV-2 transmission by banknotes and coins, we examined the stability of SARS-CoV-2 and bovine coronavirus, as surrogate with lower biosafety restrictions, on these different means of payment and developed a touch transfer method to examine transfer efficiency from contaminated surfaces to fingertips. Although we observed prolonged virus stability, our results indicate that transmission of SARS-CoV-2 via contaminated coins and banknotes is unlikely and requires high viral loads and a timely order of specific events