Control of microbial contamination in dental unit water systems using tetra-sodium EDTA

Aim:  To examine the efficacy of tetra-sodium EDTA in controlling microbial contamination of dental unit water systems (DUWS).
Methods and Results:  Ten dental units were treated once a week with either 4% or 8% tetra-sodium EDTA for four or two consecutive weeks, respectively. Before treatment, 43% and 60% of the water samples from the air/water triple syringe and high-speed hand-pieces, respectively, exceeded the American Dental Association (ADA) guidelines of 200 CFU ml⁻¹ water during a 6-week baseline period. After each weekend treatment, the levels of microbial contamination in all DUWS fell significantly ( P  < 0·001) to below the ADA guideline. By the end of the week, microbial counts in the outflowing water had returned to baseline levels indicating a transient effect of single doses of tetra-sodium EDTA, and the need for multiple applications. The biofilms were virtually eliminated after a single weekend treatment.
Conclusions:  Tetra-sodium EDTA is effective in controlling microbial contamination in DUWS.
Significance and Impact of the Study:  Inexpensive, effective and safe products for reducing the microbial load of water from DUWS are needed to meet ADA and other national guidelines. Tetra-sodium EDTA can significantly reduce microbial biofilms and bacterial counts in outflowing water, and is compatible for use in DUWS.     

Microbial biofilm formation and contamination of dental-unit water systems in general dental practice

Dental-unit water systems (DUWS) harbor bacterial biofilms, which may serve as a haven for pathogens. The aim of this study was to investigate the microbial load of water from DUWS in general dental practices and the biofouling of DUWS tubing. Water and tube samples were taken from 55 dental surgeries in southwestern England. Contamination was determined by viable counts on environmentally selective, clinically selective, and pathogen-selective media, and biofouling was determined by using microscopic and image analysis techniques. Microbial loading ranged from 500 to 10(5) CFU. ml(-1); in 95% of DUWS water samples, it exceeded European Union drinking water guidelines and in 83% it exceeded American Dental Association DUWS standards. Among visible bacteria, 68% were viable by BacLight staining, but only 5% of this "viable by BacLight" fraction produced colonies on agar plates. Legionella pneumophila, Mycobacterium spp., Candida spp., and Pseudomonas spp. were detected in one, five, two, and nine different surgeries, respectively. Presumptive oral streptococci and Fusobacterium spp. were detected in four and one surgeries, respectively, suggesting back siphonage and failure of antiretraction devices. Hepatitis B virus was never detected. Decontamination strategies (5 of 55 surgeries) significantly reduced biofilm coverage but significantly increased microbial numbers in the water phase (in both cases, P < 0.05). Microbial loads were not significantly different in DUWS fed with soft, hard, deionized, or distilled water or in different DUWS (main, tank, or bottle fed). Microbiologically, no DUWS can be considered "cleaner" than others. DUWS deliver water to patients with microbial levels exceeding those considered safe for drinking water.     

Biofilm problems in dental unit water systems and its practical control

Dental chair units (DCUs) contain integrated systems that provide the instruments and services for a wide range of dental procedures. DCUs use water to cool and irrigate DCU-supplied instruments and tooth surfaces during dental treatment. Water is supplied to these instruments by a network of interconnected narrow-bore (2–3 mm) plastic tubes called dental unit waterlines (DUWLs). Many studies over the last 40 years demonstrated that DUWL output water is often contaminated with high densities of micro-organisms, predominantly Gram-negative aerobic heterotropic environmental bacteria, including Legionella and Pseudomonas species. Untreated DUWLs host biofilms that permit micro-organisms to multiply and disperse through the water network and which are aerosolized by DCU instrument use, thus exposing patients and staff to these micro-organisms, to fragments of biofilm and bacterial endotoxins. This review concentrates on how practical developments and innovations in specific areas can contribute to effective DUWL biofilm control. These include the use of effective DUWL treatment agents, improvements to DCU supply water quality, DCU design changes, development of automated DUWL treatment procedures that are effective at controlling biofilm in the long-term and require minimal human intervention, are safe for patients and staff, and which do not cause deterioration of DCU components following prolonged use.     

Microbial diversity of biofilms in dental unit water systems

We investigated the microbial diversity of biofilms found in dental unit water systems (DUWS) by three methods. The first was microscopic examination by scanning electron microscopy (SEM), acridine orange staining, and fluorescent in situ hybridization (FISH). Most bacteria present in the biofilm were viable. FISH detected the beta and gamma, but not the alpha, subclasses of Proteobacteria: In the second method, 55 cultivated biofilm isolates were identified with the Biolog system, fatty acid analysis, and 16S ribosomal DNA (rDNA) sequencing. Only 16S identified all 55 isolates, which represented 13 genera. The most common organisms, as shown by analyses of 16S rDNA, belonged to the genera Afipia (28%) and Sphingomonas (16%). The third method was a culture-independent direct amplification and sequencing of 165 subclones from community biofilm 16S rDNA. This method revealed 40 genera: the most common ones included Leptospira (20%), Sphingomonas (14%), Bacillus (7%), Escherichia (6%), Geobacter (5%), and Pseudomonas (5%). Some of these organisms may be opportunistic pathogens. Our results have demonstrated that a biofilm in a health care setting may harbor a vast diversity of organisms. The results also reflect the limitations of culture-based techniques to detect and identify bacteria. Although this is the greatest diversity reported in DUWS biofilms, other genera may have been missed. Using a technique based on jackknife subsampling, we projected that a 25-fold increase in the number of subclones sequenced would approximately double the number of genera observed, reflecting the richness and high diversity of microbial communities in these biofilms.     

Decontamination of dental unit water systems with hydrogen peroxide

AIMS: Transmission of microbial pathogens to patients from water in dental units is a concern. To reduce this risk, the decontaminating efficiency of hydrogen peroxide was evaluated. METHODS AND RESULTS: Three percent hydrogen peroxide diluted 1 : 4 in distilled water (contact time 15 min) was used daily to disinfect the waterlines of a pilot unit previously contaminated with Pseudomonas aeruginosa or Staphylococcus aureus. The behaviour of the test bacteria was seen to differ over time. Staph. aureus numbers slowly decreased until only low numbers were recovered, after which the levels remained stable. Ps. aeruginosa abatement was more rapid and the density of the bacteria reached a peak when the circuit was empty. CONCLUSIONS: Staph. aureus and Ps. aeruginosa treated with hydrogen peroxide fell from 6 to 4 log. SIGNIFICANCE AND IMPACT OF THE STUDY: Treatment of dental unit waterlines with hydrogen peroxide was seen to be able to keep the number of the bacteria under control, as long as the treatment was repeated daily.     

Microbiological evaluation of a range of disinfectant products to control mixed-species biofilm contamination in a laboratory model of a dental unit water system

Dental unit water system (DUWS) tubing harbors complex multispecies biofilms that are responsible for high microbial levels at the distal outlet. The aim of this study was to use an established biofilm laboratory model to simulate biofouling of DUWS to evaluate practical, cost-effective, and evidence-based methods of microbial decontamination. Reproducible biofilms were developed in the model over 14 days; decontamination was assessed using total viable counts (TVC) and microscopic-image analysis techniques to view the inner surface of tubing. Flushing did not reduce the biofilm coverage or TVC. Combizyme and ozone did not completely eliminate the viable bacteria (70 and 65% reduction in biofilm TVC, respectively), nor did they remove the biofilm (45 and 57% reduction in biofilm coverage, respectively). Chlorhexidine and Bio2000 (active agent: ethanol and chlorhexidine), Tegodor and Gigasept Rapid (aldehyde based), and Grotanol (hydroxide based) completely eliminated the TVC but did not completely remove biofilm (31, 53 33, 34, and 64.9% reduction of biofilm coverage, respectively). Other products including Grotanol Flussig (phenol based), Betadine (povidone-iodine based), Alpron (chlorite based), and the hydroxide-containing products Sporklenz, Sterilex Ultra, Dialox, Sterilox, Sanosil, Oxigenal, and Grotanat Bohrerbad resulted in a 100% reduction in the biofilm TVC and a >95% reduction in biofilm coverage. The study demonstrated that while many disinfectants achieve a sufficient reduction in TVC they may not necessarily remove unwanted biofilm from the tubing surfaces as tested in this laboratory-controlled biofilm model.     

Air-borne microbial contamination of surfaces in a UK dental clinic

Little is known about the number, type, or antibiotic resistance profiles, of air-borne microbes present in hospital settings yet such information is important in designing effective measures to reduce cross-infection. In this study settle plates were used to identify and quantify the air-borne microbes present in a dental clinic. All isolates were identified to species level using partial 16S ribosomal RNA gene sequencing and their susceptibility to ampicillin, chloramphenicol, erythromycin, gentamicin, penicillin, tetracycline or vancomycin was performed. The mean numbers of viable bacteria detected for each sampling occasion during periods of clinical activity and in the absence of such activity were 21.9x10(2 )cfu/m(2)/h and 2.3x10(2 )cfu/m(2)/h respectively. One hundred ninety-three distinct colony morphotypes, comprising 73 species, were isolated during the study and 48% of these were resistant to at least one antibiotic. The mean numbers of different morphotypes detected per sampling occasion were 14.3 and 5 during periods of clinical activity and inactivity respectively. Propionibacterium acnes, Micrococcus luteus and Staphylococcus epidermidis were frequently isolated regardless of whether any clinical activities were taking place. These findings highlight the importance of preventing surfaces from becoming reservoirs of antibiotic-resistant bacteria and thereby contributing to cross-infection in the dental clinic.     

Weed biological control in the European Union: from serendipity to strategy

Biological control of weeds is a globally recognised approach to the management of some of the most troublesome invasive plants in the world. Accidental introductions of agents accounted for all weed biological control agent establishments in the European Union until 2010, but these examples include some current or emerging control successes both large and small, from the redistribution of the weevil Stenopelmus rufinasus Gyllenhal (Coleoptera: Curculionidae) for the control of small outbreaks of Azolla filiculoides Lam. (Azollaceae), to the large scale control provided by the cochineal insect Dactylopius opuntiae (Cockerell) (Hemiptera: Dactylopiidae), used against some problematic prickly pears (Opuntia spp. (Cactaceae)), and the ragweed beetle Ophraella communa LeSage (Coleoptera: Chrysomelidae), against common ragweed, Ambrosia artemisiifolia L. (Asteraceae), which are providing benefits to an increasing number of Member States of the European Union. Recent programmes involving the intentional introduction of biological control agents against target weeds including Fallopia japonica (Hout.) Ronse Decr. (Polygonaceae), Impatiens glandulifera Royle (Balsaminaceae) and Acacia longifolia (Andrews) Willd (Fabaceae) show a shift from luck to judgement in the European Union. The inclusion of new weed targets on the European Invasive Species Regulation should lead to a growth in the profile and use of biological control which would be assisted by the publication of any successes from the few intentional introductions covered in this paper.     

Comparison of bacterial composition between human saliva and dental unit water system

The bacterial compositions between the dental unit water system and human saliva were characterized and compared by direct sequence analysis of 16S rDNA clone libraries. Based on the species richness estimation, bacterial diversity in the dental unit water system (DUW) was more diverse than that of the human saliva (HS). The Chao1 estimates of species richness in HS and DUW samples were 12.0 and 72.4, respectively. The total numbers of OTUs observed in the combined libraries accounted for 83% (HS) and 59% (DUW) of the Chao1 diversity estimate as defined at the 80% similarity threshold. Based on the sequence analysis, the phylum Proteobacteria was the major group in both clone libraries at phylum level. DUW clone library contained 80.0% Proteobacteria, 8.0% Bacteroides, 4.0% Nitrospira, 4.0% Firmicutes, 2.0% Planctomycetes and 2.0% Acidobacteria. On the other hand, human saliva (HS) clone library contained 55.5% Proteobacteria, 36.1% Firmicutes and 8.4% Bacteroides. The majority of bacteria identified belonged to phylum Proteobacteria in both samples. In dental unit water system (DUW), Alphaproteobacteria was detected as the major group. There was no evidence of the bacterial contamination due to a dental treatment. Most sequences were related to microorganisms derived from biofilm in oligotrophic environments.     

Current practices and emerging possibilities for reducing the spread of oomycete pathogens in terrestrial and aquatic production systems in the European Union

Diseases caused by oomycete pathogens are a global threat to forestry, agriculture and aquaculture. Because of their complex life cycles, characterised by dormant resting structures that enable their survival for years under hostile environmental conditions, reducing the spread of oomycetes is a challenging task. In this review, we present an overview of this challenge, starting from the need to understand the natural and anthropogenic dispersal pathways of these pathogens. Focusing on the European Union, we explore current legislation that forms a backbone for biosecurity protocols against the spread of oomycetes through trade and transport. We discuss the options for prevention, containment and long-term management of oomycetes in different production settings, emphasising the importance of prevention as the most cost-efficient strategy to reduce the spread of these pathogens. Finally, we highlight some of the new and emerging technologies and strategies as potential tools in the integrated pest management of animal and plant diseases caused by oomycetes. We emphasise the urgency of actions to halt the global spread of these pathogens.     

Comparison of the Efficacies of Disinfectants To Control Microbial Contamination in Dental Unit Water Systems in General Dental Practices across the European Union

Water delivered by dental unit water systems (DUWS) in general dental practices can harbor high numbers of bacteria, including opportunistic pathogens. Biofilms on tubing within DUWS provide a reservoir for microorganisms and should be controlled. This study compared disinfection products for their ability to meet the American Dental Association's guideline of <200 CFU · ml⁻¹ for DUWS water. Alpron, BioBlue, Dentosept, Oxygenal, Sanosil, Sterilex Ultra, and Ster4Spray were tested in DUWS (n = 134) in Denmark, Germany, Greece, Ireland, The Netherlands, Spain, and the United Kingdom. Weekly water samples were tested for total viable counts (TVCs) on yeast extract agar, and, where possible, the effects of products on established biofilm (TVCs) were measured. A 4- to 5-week baseline measurement period was followed by 6 to 8 weeks of disinfection (intermittent or continuous product application). DUWS water TVCs before disinfection ranged from 0 to 5.41 log CFU · ml⁻¹. Disinfectants achieved reductions in the median water TVC ranging from 0.69 (Ster4Spray) to 3.11 (Dentosept) log CFU · ml⁻¹, although occasional high values (up to 4.88 log CFU · ml⁻¹) occurred with all products. Before treatment, 64% of all baseline samples exceeded American Dental Association guidelines, compared to only 17% following commencement of treatment; where tested, biofilm TVCs were reduced to below detectable levels. The antimicrobial efficacies of products varied (e.g., 91% of water samples from DUWS treated with Dentosept or Oxygenal met American Dental Association guidelines, compared to 60% of those treated with Ster4Spray). Overall, the continuously applied products performed better than those applied intermittently. The most effective products were Dentosept and Oxygenal, although Dentosept gave the most consistent and sustained antimicrobial effect over time.     

Epidemiology and control prospects of foodborne parasitic zoonoses in the European Union

In the 27 Member States of the European Union, zoonotic parasites transmitted by food are circulating with different prevalence according to the country, the environmental conditions, the human behaviour, and the socio-economic level. Foodborne parasites can be divided in two main groups according to the way of transmission to humans. These foodborne parasites reach the human beings through the consumption of raw infected food such as muscle tissues of different animal species (Toxoplasma gondii, Sarcocystis hominis, Sarcocystis suishominis, Diphyllobotrium latum, Taenia solium, Taenia saginata, Opisthorchis felineus, Anisakis spp., Pseudoterranova spp., Trichinella spp.), or vegetables (Fasciola hepatica), and contaminated food and water resources (Giardia duodenalis, Cryptosporidium spp., T. gondii, Echinococcus granulosus sensu latu, Echinococcus multilocularis, T. solium, Taenia multiceps). As a general role, the control strategies should be based on the education of the consumers, farmers and shepherds, the improvement of farming conditions, the improvement or the development of more sensitive methods to detect these parasites in slaughtered animals and in foodstuff, a control of sewage sludge on pastures and of drinking water resources, and the reduction of contacts between livestock and wild animals which frequently represent the most important reservoir of these pathogens.     

Faecal contamination of drinking water sources of Dhaka city during the 2004 flood in Bangladesh and use of disinfectants for water treatment

AIMS: To describe the extent of faecal pollution and point of use water treatment strategy during and after the 2004 flood in Dhaka. METHODS: A total of 300 water samples were collected from 20 different drinking water sources in Kamalapur, Dhaka city from August 2004 to January 2005. The level of faecal contamination was estimated using measurements of faecal indicator bacteria (total coliforms, faecal coliforms and faecal streptococci) and isolation of Vibrio cholerae was carried out following standard procedures. Total dissolved solids, dissolved oxygen, hardness, chloride and pH were also monitored. The efficacy of four disinfectants including Halotab, Zeoline-200, alum potash and bleaching powder were tested as point of use water treatment agents. The unacceptable level of contamination of total coliforms (TC), faecal coliforms (FC) and faecal streptococci (FS) ranged from 23.8% to 95.2%, 28.6% to 95.2% and 33.3% to 90.0%, respectively. The isolation rates of V. cholerae O1 and O139 were both 0.33%, and non-O1/non-O139 was 7.0%. CONCLUSION: Water collected during and after floods was contaminated with TC, FC, FS and V. cholerae. Although alum potash, bleaching powder, Halotab and Zeoline-200 were all effective general disinfectants, Halotab and Zeoline-200 were superior to bleaching powder and alum potash against FC. SIGNIFICANCE AND IMPACT OF THE STUDY: During and after floods, point of use water treatment could reduce waterborne diseases among flood-affected people.     

Comparison of curricula in radiation technology in the field of radiotherapy in selected European Union countries

Background

Radiation technology is a discipline of medical science which deals with diagnostics, imaging and radiotherapy, that is treatment by ionizing radiation.

Aim

To present and compare the existing curricula of radiation technology in selected EU countries.

Materials and methods

The research work done for the purpose of the comparative analysis was based on the methods of diagnostic test and document analysis.

Results

The comparison of curricula in selected countries, namely Austria, France, the Netherlands and Poland, showed that admission criteria to radiation technology courses are varied and depend on regulations of respective Ministries of Health. The most restrictive conditions, including written tests in biology, chemistry and physics, and psychometric test, are those in France. Contents of basic and specialist subject groups are very similar in all the countries. The difference is in the number of ECT points assigned to particular subjects and the number of course hours offered. The longest practical training is provided in the Netherlands and the shortest one in Poland. The duration of studies in the Netherlands is 4 years, while in Poland it is 3 years. Austria is the only country to offer extra practical training in quality management.

Conclusion

Graduates in the compared EU countries have similar level of qualifications in the fields of operation of radiological equipment, radiotherapy, nuclear medicine, foreign language and specialist terminology in the field of medical and physical sciences, general knowledge of medical and physical sciences, and detailed knowledge of radiation technology.     

Comparison of new Brazilian legislation for the approval of advanced therapy medicinal products with existing systems in the USA,European Union and Japan

Background aimsAdvanced therapy medicinal products (ATMPs) are a class of biological products for human use that are based on genes, cells and tissues. The first ATMP received marketing authorization in Europe in 2009, whereas Brazil granted the first authorization in 2020. The objective of this study was to compare the regulatory models adopted by Brazil, the USA, Japan and the European Union, which comprise the member countries of the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use, with regard to the marketing authorization of ATMPs.MethodsThe authors performed a review of the scientific literature and official documents of the regulatory agencies in the aforementioned countries.ResultsThe legislation and regulatory guidelines adopted by the regulatory agencies exhibit similarities and differences. It was not possible to assess whether these differences can be translated into divergent final recommendations by regulatory authorities upon a request for marketing authorization.ConclusionsIn the future, it will be appropriate to start a progressive process of harmonization between these agencies in terms of terminology, legal recommendations and characterization requirements. This is particularly important for emerging countries such as Brazil. In this sense, some measures can be taken to achieve alignment between regulators.     

植物离体培养中微生物污染的鉴定与控制(综述)

本文综述植物离体培养过程中微生物污染的鉴定与控制的研究进展,包括通过指示培养和菌种鉴别以鉴定污染菌;从保护条件下生长的植株上取材以及材料的预处理,以便有效地控制附生菌和应用抗生素控制内生菌.     

Strategic dilemmas of biosecurity in the European Union

Systems for societal/homeland security in both Europe and the United States are in flux to adjust to 21st century threats, such as terrorism, the proliferation of weapons of mass destruction, regional conflicts, state failures, and organized crime. It is important that reforms take place on both sides of the Atlantic that recognize the interdependence of Europe and the United States. Security, including biosecurity, for Europe is strongly connected to security in the U.S. Diseases transcend borders, and their consequences can be the same, irrespective of where the outbreak occurs or whether it is a natural occurrence or an act of bioterrorism. This article examines the political and strategic dilemmas and complexities that would confront the European Union (EU) in the event of a bioterrorism attack or a naturally occurring outbreak. Although several initiatives have been taken by the 15 member states and within the EU Commission, the EU is not institutionally prepared for transnational, rapidly moving diseases that could cause grave consequences in Europe and other regions, including the U.S. The prime responsibility for protecting European citizens against outbreaks rests with each member state. However, with intertwined and open European societies, the consequences would likely spill across borders. The EU Commission would have to become involved because such aspects as the internal market and freedom of movement would be affected. Responsibility, but not authority, would be pushed to the top. A coordinated EU response to such crises depends on European political leadership.