The Bead Assay for Biofilms: A Quick, Easy and Robust Method for Testing Disinfectants

Bacteria live primarily in microbial communities (biofilms), where they exhibit considerably higher biocide tolerance than their planktonic counterparts. Current standardized efficacy testing protocols of disinfectants, however, employ predominantly planktonic bacteria. In order to test the efficacy of biocides on biofilms in a standardized manner, a new assay was developed and optimized for easy-handling, quickness, low running costs, and above all—repeatability. In this assay, 5 mm glass- or polytetrafluoroethylene beads in 24 well microtiter plates served as substrate for Pseudomonas aeruginosa biofilms. After optimizing result-relevant steps, the actual performance of the assay was explored by treating P. aeruginosa biofilms with glutaraldehyde, isopropanol, or peracetic acid in predefined concentrations. The aspired 5 log10 reduction in CFU counts was achieved by glutaraldehyde at 5% (30 min), and by peracetic acid at 0.3% (10 min). In contrast, 80% isopropanol (30 min) failed to meet the reduction goal. However, the main accomplishment of this study was to unveil the potential of the array itself; most noteworthy here, a reliable repeatability of the results. The new bead assay for biofilms is a robust, quick and cost-effective method for assessing the efficacy of biocides against biofilms

Ethanol is indispensable for virucidal hand antisepsis: memorandum from the alcohol-based hand rub (ABHR) Task Force, WHO Collaborating Centre on Patient Safety, and the Commission for Hospital Hygiene and Infection Prevention (KRINKO), Robert Koch Institute, Berlin, Germany

Background: The approval of ethanol by the Biocidal Products Regulation has been under evaluation since 2007. This follows concern over alcohol uptake from ethanol-based hand rubs (EBHR). If ethanol is classified as carcinogenic, mutagenic, or reprotoxic by the European Chemicals Agency (ECHA), then this would affect infection prevention and control practices. Aim: A review was performed to prove that ethanol is toxicological uncritical and indispensable for hand antisepsis because of its unique activity against non-enveloped viruses and thus the resulting lack of alternatives. Therefore, the following main points are analyzed: The effectiveness of ethanol in hand hygiene, the evidence of ethanol at blood/tissue levels through hand hygiene in healthcare, and the evidence of toxicity of different blood/tissue ethanol levels and the non-comparability with alcoholic consumption and industrial exposure. Results: EBHR are essential for preventing infections caused by non-enveloped viruses, especially in healthcare, nursing homes, food industry and other areas. Propanols are effective against enveloped viruses as opposed to non-enveloped viruses but there are no other alternatives for virucidal hand antisepsis. Long-term ingestion of ethanol in the form of alcoholic beverages can cause tumours. However, lifetime exposure to ethanol from occupational exposure < 500 ppm does not significantly contribute to the cancer risk. Mutagenic effects were observed only at doses within the toxic range in animal studies. While reprotoxicity is linked with abuse of alcoholic beverages, there is no epidemiological evidence for this from EBHR use in healthcare facilities or from products containing ethanol in non-healthcare settings. Conclusion: The body of evidence shows EBHRs have strong efficacy in killing non-enveloped viruses, whereas 1-propanol and 2-propanol do not kill non-enveloped viruses, that pose significant risk of infection. Ethanol absorbed through the skin during hand hygiene is similar to consumption of beverages with hidden ethanol content (< 0.5% v/v), such as apple juice or kefir. There is no risk of carcinogenicity, mutagenicity or reprotoxicity from repeated use of EBHR. Hence, the WHO Task Force strongly recommend retaining ethanol as an essential constituent in hand rubs for healthcare

How long do nosocomial pathogens persist on inanimate surfaces? A systematic review

BACKGROUND: Inanimate surfaces have often been described as the source for outbreaks of nosocomial infections. The aim of this review is to summarize data on the persistence of different nosocomial pathogens on inanimate surfaces. METHODS: The literature was systematically reviewed in MedLine without language restrictions. In addition, cited articles in a report were assessed and standard textbooks on the topic were reviewed. All reports with experimental evidence on the duration of persistence of a nosocomial pathogen on any type of surface were included. RESULTS: Most gram-positive bacteria, such as Enterococcus spp. (including VRE), Staphylococcus aureus (including MRSA), or Streptococcus pyogenes, survive for months on dry surfaces. Many gram-negative species, such as Acinetobacter spp., Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, Serratia marcescens, or Shigella spp., can also survive for months. A few others, such as Bordetella pertussis, Haemophilus influenzae, Proteus vulgaris, or Vibrio cholerae, however, persist only for days. Mycobacteria, including Mycobacterium tuberculosis, and spore-forming bacteria, including Clostridium difficile, can also survive for months on surfaces. Candida albicans as the most important nosocomial fungal pathogen can survive up to 4 months on surfaces. Persistence of other yeasts, such as Torulopsis glabrata, was described to be similar (5 months) or shorter (Candida parapsilosis, 14 days). Most viruses from the respiratory tract, such as corona, coxsackie, influenza, SARS or rhino virus, can persist on surfaces for a few days. Viruses from the gastrointestinal tract, such as astrovirus, HAV, polio- or rota virus, persist for approximately 2 months. Blood-borne viruses, such as HBV or HIV, can persist for more than one week. Herpes viruses, such as CMV or HSV type 1 and 2, have been shown to persist from only a few hours up to 7 days. CONCLUSION: The most common nosocomial pathogens may well survive or persist on surfaces for months and can thereby be a continuous source of transmission if no regular preventive surface disinfection is performed

Haben wir seine Botschaft verstanden? – Ein Abriss zur Geschichte der Händehygiene anlässlich des 200. Geburtstages von Ignaz Philipp Semmelweis

Das Epidemiologische Bulletin 18/2018 beleuchtet die historische und aktuelle Entwicklung der Händedesinfektion. Anlass ist der 200. Geburtstag des Frauenarztes Ignaz Semmelweis am 1. Juli, der als Begründer der Händedesinfektion gilt. Am 5. Mai ist zudem „Internationaler Tag der Händehygiene“, der 2009 von der WHO initiiert wurde und alljährlich die Aufmerksamkeit auf die Händehygiene in medizinischen und pflegerischen Einrichtungen lenken soll.Peer Reviewe

Dichtung und Wahrheit – von Mythen, Irrtümern und Begleitumständen zur Händedesinfektion

Im Epidemiologischen Bulletin 19/2019 gehen zwei Beiträge auf das Thema Händehygiene in medizinischen und pflegerischen Einrichtungen ein, zum einen auf "Mythen, Irrtümer und Begleitumstände zur Händedesinfektion" und zum anderen auf "Nutzen und Risiko bei der Verwendung von pathogenfreien medizinischen Einmalhandschuhen". Anlass ist der von der Weltgesundheitsorganisation 2009 initiierte „Internationale Tag der Händehygiene“ am 5.5. Das Datum symbolisiert die fünf Finger der zwei Hände. Mit dem Tag soll die Aufmerksamkeit auf die Händehygiene in medizinischen und pflegerischen Einrichtungen gelenkt werden. In der WHO-Kampagne wird besonders die Händedesinfektion als die wirksamste Einzelmaßnahme zur Unterbrechung von Infektionsketten hervorgehoben.Peer Reviewe

Aktueller Stand zur Viruzidieprüfung – ein Überblick

Die Arbeit befasst sich mit der Entwicklung der Viruzidietestung insbesondere in Deutschland. Die gegenwärtig zur Verfügung stehenden Prüfmethoden in Form von Suspension- bzw. praxisnahen Tests werden vorgestellt und erläutert. Basierend auf Prüfungen mit diesen Tests existieren verschiedene Listen bzw. Zusammenstellungen zur Viruswirksamkeit von Desinfektionsmitteln, deren jeweilige Besonderheiten beschrieben werden.The paper addresses the development of virucidal testing especially in Germany. Currently existing test methods for suspension and practical tests are presented and explained. Based on results of these tests different lists and compilations on virucidal efficacy of disinfectants exist. The characteristics of these lists are described

Evaluation of Virus Inactivation by Formaldehyde to Enhance Biosafety of Diagnostic Electron Microscopy

Formaldehyde (FA) fixation of infectious samples is a well-established protocol in diagnostic electron microscopy of viruses. However, published experimental data that demonstrate virus inactivation by these fixation procedures are lacking. Usually, fixation is performed immediately before the sample preparation for microscopy. The fixation procedure should transform viruses in a non–infectious but nonetheless structurally intact form in order to allow a proper diagnosis based on morphology. FA provides an essential advantage in comparison to other disinfectants, because it preserves the ultrastructure of biological material without interfering significantly with the preparation (i.e., the negative staining) and the detection of viruses. To examine the efficiency of FA inactivation, we used Vaccinia virus, Human adenovirus and Murine norovirus as models and treated them with FA under various conditions. Critical parameters for the inactivation efficiency were the temperature, the duration of the FA treatment, and the resistance of the virus in question. Our results show that FA inactivation at low temperature (4 °C) bears a high risk of incomplete inactivation. Higher temperatures (25 °C) are more efficient, although they still require rather long incubation times to fully inactivate a complex and highly robust virus like Vaccinia. A protocol, which applied 2% buffered FA for 60 min and a temperature–shift from 25 to 37 °C after 30 min was efficient for the complete inactivation of all test viruses, and therefore has the potential to improve both biosafety and speed of diagnostic electron microscopy