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PubMed1975

Investigations on the efficacy of surface disinfection and surface cleaning procedures. 1. Tests under real-life conditions.

The suitability of disinfection preparations is assessed on the basis of laboratory tests, different methods being used in the various countries. Since such model tests are rather inadequate when it comes to judging surface disinfectants, additional in-use tests are desirable. They might, in any case, serve as a reference system for judging the evaluation criteria which still differ widely at the moment. The experiments described in this study were chiefly designed to establish the effect of cleaning and disinfection measures on bacteria normally present on surfaces and on the artificial contamination of surfaces with Sarcinae as model germs. The tests were carried out in the halls on 5 floors of a medical (lift landings). "Rodac" plates were used to identify the germs. 3 disinfectants (aldehydes, phenol derivative), 3 disinfectant cleaning agents and soft soap were used. The preparations reduced the normal germ count by approx. 80 per cent. The reduction was mainly due to the cleaning effect (soft soap was as effective as the preparations with disinfectant properties). The effect on the "normal germ count" cannot, therefore, be used as sole criterion of disinfectant action. When the various preparations were applied in twice the concentration recommended for Staphylococcus hospitalism, the Sarcina count was reduced by 99 to 99.9 per cent within 2 hours. The efficacy of disinfectants and disinfectant cleaning agents was practically the same. Additional laboratory tests are necessary before the effect of soft soap can be finally assessed. In actual practice the unit count of pathogenic germs- such as Staphylococci and Klebsiellae- is too low to enable an objective assessment of a disinfectant to be made. On the other hand, artificial contamination with such pathogens is not possible because of the risk involved. The use of Sarcina lutea as test germ is therefore subjects to certain limitations. One of the prerequisites for using it is, for example, prior reduction of the normal germ count to values of less than 500/100 cm2. The second communication will report on investigations into the chemoresistance of Sarcina and how this compares with that of Staphylococcus aureus and Klebsiella. The need for such studies arose from our present investigation.

Cell Count↗
PubMed2004

Assessment of enzymatic cleaning agents and disinfectants against bacterial biofilms.

PURPOSE: Microbial biofilm has become difficult to control by antibiotic and biocide regimes that are effective against suspended bacteria. Their colonization of surfaces can be a problem and is generally controlled through cleaning and disinfection. This study was undertaken to examine the efficacy of the disinfectants including Bio-Ow, Econase CE, Gamanase GC 140, IndiAge 44L, Mannanase AMB, Multifect P-3000, Neutrase, Pandion, Paradigm, Pectinex Ultra SP-L, Promozyme, Resinase A2X, Spezyme AA300, Spezyme GA300 and Vinozym EC, and the proteinase against bacterial biofilms. METHODS: The effectiveness of 20 commercial disinfectants against Pseudomonas aeruginosa (P. aeruginosa) biofilms using a fluorometric technique was examined. Additionally the disinfectants were also tested against Lactobacillus bulgaricus (L. bulgaricus), Lactobacillus lactis (L. lactis) and Streptococcus thermophilus (S. thermophilus) isolates using microtitration tray based turbidimetric techniques. Escherichia coli (E. coli) was used as the test bacteria in the fluorometric control method. RESULTS: Among the first group of the enzymatic cleaning agents tested, four disinfectants (Pandion, Resinase A2X, Spezyme GA300 and Paradigm) were the most potent against bacterial biofilms after 30 min incubation time (residual bacterial count less than 10(3) CFU (colony forming units)/ml). However, only Resinase A2X and Paradigm showed a good effect on bacterial biofilms after 15 min incubation time. Proteinase disinfectants (alkalase, chymotrypsin, cryotin and krilltrypsin) from the second group of the disinfectants showed a good effect against P. aeruginosa biofilm when tested in the absence of milk. The performance of the disinfectants was reduced in the presence of milk. The minimum inhibitory concentration (MIC) of the cleaning agents was determined as the lowest concentration inhibiting bacterial growth. The MIC was tested on Lactobacillus bulgaricus (L. bulgaricus), Lactobacillus lactis (L. lactis) and Streptococcus thermophilus (S. thermophilus) isolates. The minimum inhibitory concentrations (MIC) for Paradigm against S. thermophilus and L. Lactis were lower than L. Bulgaricus. Whereas, the MIC of Pandion against L. bulgaricus was lower than MIC against L. lactis. Resinase A2X had no inhibitory effect on bacterial growth when the concentration was less than or equal to 2.4 mg/ml and Spezyme GA 300 concentration less than or equal to 7.3 mg/ml. Minimum inhibitory concentration of Pandion against L. bulgaricus was 2.7 microg/ml and against L. lactis 5.3 microg/ml. Growth of S. thermophilus was inhibited in all concentration of Pandion tested. CONCLUSIONS: The choice of disinfectant or cleaning agent along with the optimum concentration and the time of action is very important when destroying microbes. It is also important that the resistances of microbes to different disinfectants and cleaning agents be taken into account when planning the cleaning process

Biofilms↗
PubMed1996

In-hospital evaluation of 7.5% hydrogen peroxide as a disinfectant for flexible endoscopes.

The effectiveness of Sporox (Reckitt and Colman Inc, New Jersey), a 7.5% solution of hydrogen peroxide, was compared with that of Cidex (Johnson & Johnson), a 2% solution of alkaline glutaraldehyde, in the manual disinfection of flexible endoscopes at a large general hospital. For disinfection with Sporox, a soaking time of 10 mins at room temperature was used. The same disinfectant bath was used for nearly seven weeks and the Sporox level was monitored using reagent strips supplied with the product. Controls included endoscopes with precleaning (enzyme-detergent) but without any disinfection, and endoscopes that were precleaned and disinfected in Cidex only. A total of 3 mL of sterile normal saline was used for sampling each channel and immediately plated to detect aerobic and anaerobic bacteria as well as mycobacteria. There were 76 endoscopes sampled. Of these, 55 were disinfected in Sporox, 13 were disinfected in Cidex and eight were precleaned but not disinfected. None of the samples from endoscopes disinfected with either Sporox or Cidex yielded isolates generally regarded as pathogenic for humans. The findings of this in-hospital study indicate that Sporox is at least as efficacious as Cidex in the disinfection of flexible endoscopes between patients. In addition, the exposure time to Sporox was half as long compared with Cidex, and hydrogen peroxide is much less toxic to humans and the environment. Therefore, Sporox appears to have considerable potential as a safer substitute for glutaradehyde-based products in the decontamination of flexible endoscopes.

Anti-Infective Agents, Local↗
PubMed1976

[Test for the efficacy of disinfectants at surfaces in test models. I. (communication:) Dependence of experimental results on the method of demonstration of surviving germs (swab and rinsing) (author's transl)].

For the testing of disinfectants at surfaces, the germs having survived at the surface are demonstrated by means of swabs according to the guide-lines of the Deutsche Gesellschaft fur Hygiene und Mikrobiologie (DGHM): after the period of exposure to the disinfectant, the surfaces were rubbed off with a damp swab, and the frictional surface of the swab was plated out on nutrient agar. The effectiveness of this technique was compared with the effectiveness of a rinsing method in a test model. In the rinsing process, the objects to be tested for surviving germs were shaken together with a suspension and with glass beads. Then the content of germs in the suspension was quantitatively determined by means of dilution tests and pour plates. The findings were evaluated according to the guide-lines for evaluation of the DGHM (less than or equal to 10 surviving germs = adequate efficacy). For the findings obtained by rinsing, the average number of surviving germs was also determined. For maldehyde solutions were used as disinfectants for the test models (time of exposure: 4 hours; temperature 22 to 25 degrees C). These disinfecting experiments were performed on raw smoothed as well as on varnished beech-wood. The experimental results showed that the criterion "less than or equal to X surviving germs" in itself does not mean clear evidence of the efficacy of a disinfectant. The one and only decisive criterion is the frequency of the statement that a certain disinfectant or a corresponding dilution of this disinfectant has shown adequate efficacy. Therefore, one single test according to the guide-lines of the DGHM is insufficient. The frequency of the finding "adequate efficacy" is not only dependent on the concentration of the disinfectant but also on the technique used for the demonstration of surviving germs. The swab method (according to the guide-lines of the DGHM) occasionally resulted in the finding "adequate efficacy" already if 10(4) to 10(5) surviving germs were demonstrable by the rinsing method. The range of formaldehyde concentrations for which the finding of adequate efficacy were present with a frequency between 20% (minimum) and 80% (maximum) amounted to 0.2-0.5% (varnished surface) and 1.1-2.5% (raw surface), respectively for the swab method. The respective figures for the rinsing method were 0.8-1.3% and 4.8-6.5%, respectively. When using the swab method, there is a slower increase in the efficacy of the disinfectant with concentration as compared with the rinsing method. The rinsing method is, therefore, more representative of the efficacy of a disinfectant than the swab method. On account of the results of this study, it is recommended for model experiments to recover the surviving germs quantitatively by the rinsing method and to determine their number.

Disinfectants↗
PubMed1975

[Virucidal activity of the disinfectant "gigasept" against different enveloped and non-enveloped RNA-and DNA-viruses, pathogenic for men. I. Investigation in the suspension test (author's transl)].

"Gigasept" is a highly efficient chemical disinfectant on the basis of succine dialdehyde and form aldehyde. The virucidal capacity was assayed in the suspension test procedure with different representative RNA and DNA viruses with and without an envelope, such as polio wild virus type I, coxsackie virus type B 3, adeno virus type 3, herpes virus type ) and vaccinia virus. Parameter for disinfectant activity was the virus inactivation kinetic, i. e. interdependence of titer reduction vs. disinfectant concentration and disinfectant contact time. A "minimal disinfection" was defined as a greater than or equal to 99.9% virus inactivation. A "disinfection per definitionem" must gain a titer reduction of greater than or equal to 10(3) ID 50 and absence of virus. According to these criteria all virus strains were inactivated by Gigasept regardless of absence or presence of serum, which was tested in a concentration of 40% calf serum. Disinfection per definitionem was achieved with Gigasept concentrations of 3% after 60 min. or 5% after 30 min. except for enteroviruses. This group of viruses has to be disinfected with a 10% solution for 4 hours or with a 5% solution overnight. Gigasept, on the basis of these results, can be classified as a highly effective virucidal disinfectant. As to the hepatitis virus group however, no data so far are available. An enterovirus - disinfection procedure is recommended in hepatitis risk areas, as long as test systems for hepatitis viruses are not developed.

Adenoviridae↗
PubMed1995

Disinfection: gaps between recommended and actual practice.

Basic practices on disinfection was surveyed in 6 hospitals using an observation and interview checklist. Two surveys were done, one pre-(first survey) and one post-intervention (second survey). The disinfection and sterilization policy of the Ministry of Health was not available in 66 (70.2%) and 12 (13%) of the units in the first and second survey respectively. In the second survey, staff in all the units washed disinfectant containers before refilling compared with 41.5% of the units in the first survey. Dilution of disinfectants not recommended was found to be used in the first survey. Storing cleaned and sterile items in disinfectants, using disinfectant as a substitute for sterilization of autoclavable items and not decontaminating spillages were some of the wrong practices observed. Considerable improvements were made in the second survey. Improper usage of disinfectants was also indicated by failure of the in-use test. Rate of failure of disinfectants in-use decreased from 11.6% in the first survey to 5.0% in the second survey. To ensure proper disinfection practices, a comprehensive training program on disinfection is required for nurses and attendants.

Data Collection↗
PubMed2001

Advances in disinfection testing and modelling.

AIMS: To develop a set of kinetic equations which more ably describe the disinfection process. METHODS AND RESULTS: A group of functions, the fat equations, based on the model used for the quantification of microbial inhibition, was produced. These functions introduce a limit to the numbers of micro-organisms capable of being disinfected. These new expressions were shown to be more general forms of currently-used (e.g. log-linear) disinfection models, and accommodate the lags and/or tails of non-linear log-survivor--time plots. An advance in the experimental procedures used to obtain disinfection data, using an optical density technique, was developed concomitantly. CONCLUSION: The methods of analyses (experimental and modelling) allow the researcher to examine, more ably, five-minute disinfection (or specific time disinfection tests) as well as the more important disinfection rate analyses. SIGNIFICANCE AND IMPACT OF THE STUDY: The fat equations are an improvement over commonly-used rate models of disinfection, which are shown to be special cases of these equations. This raises the question as to whether our current understanding of the kinetic basis of disinfection requires revision.

Chloramphenicol↗
PubMed2001

The effect of interfering substances on the disinfection process: a mathematical model.

AIMS: To gain a greater understanding of the effect of interfering substances on the efficacy of disinfection. METHODS AND RESULTS: Current kinetic disinfection models were augmented by a term designed to quantify the deleterious effect of soils such as milk on the disinfection process of suspended organisms. The model was based on the assumption that inactivation by added soil occurred at a much faster rate than microbial inactivation. The new model, the fat-soil model, was also able to quantify the effect of changing the initial inoculum size (1 x 10(7)-5 x 10(7) ml(-1) of Staphylococcus aureus) on the outcome of the suspension tests. Addition of catalase to the disinfection of Escherichia coli by hydrogen peroxide, resulted in changes to the shape of the log survivor/time plots. These changes were modelled on the basis of changing biocide concentration commensurate with microbial inactivation. CONCLUSIONS: The reduction in efficacy of a disinfectant in the presence of an interfering substance can be quantified through the use of adaptations to current disinfection models. SIGNIFICANCE AND IMPACT OF THE STUDY: Understanding the effect of soil on disinfection efficacy allows us to understand the limitations of disinfectants and disinfection procedures. It also gives us a mechanism with which to investigate the soil tolerance of new biocides and formulations.

Animals↗
PubMed1999

Effect of disinfectant application methods on the bond strength of composite to dentin.

The use of cavity disinfectants with composite resins has raised important questions regarding their potential adverse effects on bond strength. The purpose of this study was to evaluate the effect of cavity disinfection on the bond strength of composite resin to dentin. Buccal surfaces of 64 caries-free extracted human third molars were ground flat by diamond flat-end cylinder bur, polished with a series of silicon carbide abrasive papers and mounted in autopolymerizing acrylic resin. They were randomly distributed into four groups (of 16). In group 1 (control group), dentin surfaces were treated with 35% phosphoric acid, Permagen primer and Permagen bonding resin and no disinfectant was used. In group 2, cavity disinfectant was applied and acid etching, priming and bonding procedures were performed as in group 1. In group 3, cavity disinfectant was applied after acid etching. In group 4, cavity disinfectant was applied as in group 3, but it was rinsed off before priming and bonding procedures. Then a Teflon mould 3 mm thick and 4 mm in diameter was attached to the dentin surfaces, filled with composite resin and light polymerized. After the specimens had been thermocycled, shear bond strengths were determined. Application of the disinfectant before or after acid etching significantly reduced the shear bond strength of composite to dentin (P<0.05). Rinsing off the cavity disinfectant before the bonding procedure did not affect the bond strength (P>0.05). The use of cavity disinfectant with composite resin restorations can influence the dentin bond strength.

Acid Etching, Dental↗
PubMed1997

Italian National Survey of Digestive Endoscopy Disinfection Procedures.

BACKGROUND AND STUDY AIMS: Inadequate disinfection of endoscopes and associated instrumentation can result in transmission of bacterial infections to patients. The aim of this study was to investigate the disinfection procedures carried out in the Italian centers of digestive endoscopy. MATERIALS AND METHODS: An anonymous postal questionnaire on the methods of cleaning and disinfecting endoscopy equipment in Italy was sent to 781 digestive endoscopy centers; 386 units (49.4 %) replied. RESULTS: Automatic washers were available in 47.6% of units. Nearly all the respondets (99.2%) cleaned the instruments before disinfection, using detergent, germicidal or enzymatic cleaner, but only 69.7% carried out brushing. Most centers (89.2 %) used a glutaraldehyde-based disinfectant (51 % used 2 % glutaraldehyde; 26.9% used 0.4% glutaraldehyde with 1.41% phenol and 0.26% sodium phenate; 5.9% used either; 5.4% did not specify glutaraldehyde formulation). The contact time of the disinfectant was < 10 minutes (1.8%), between 10 and 19 minutes (47.4%), between 20 and 29 minutes (31.9 %) and > or = 30 minutes (16.6%). The use-life of the disinfectant was > or = 14 days in 27.3 % of the centers with automatic washers and 30.8% in all centers. Only 25.4% of the centers carried out some form of sterilization for biopsy forceps. The majority (83.4 %) modified their disinfection procedures in the case of infectious disease patients. Quality control tests on the efficacy of the endoscopy disinfection procedures were carried out in 44.6 % of units. Only 43 % of the centers were based in hospitals with an infection control (surveillance) program. CONCLUSIONS: The data collected in the study showed that, in general, there is compliance with the Società Italiana di Endoscopia Digestiva (SIED) and Società Italiana di Gastroenterologia (SIGE) guidelines, although with some important exceptions.

Data Collection↗
PubMed2004

Assessing the residual antibacterial activity of clinical materials disinfected with glutaraldehyde, o-phthalaldehyde, hydrogen peroxide or 2-bromo-2-nitro-1,3-propanediol by means of a bacterial toxicity assay.

This study investigated the use of a rapid bacterial toxicity test for detecting disinfectant residues released by disinfected materials. The test substances included an environmental disinfectant used in hospitals in high-risk areas, such as critical care units or emergency services, and three disinfectants used on clinical devices when a high level of disinfection is required. The test materials were polyurethane, polypropylene, glass, latex and cotton from different instruments and utensils used in hospitals. Of the four test disinfectants, o-phthalaldehyde (OPA) and 2-bromo-2-nitro-1,3-propanediol (BNP) showed the greatest inhibitory activity (as much as 300-fold greater than hydrogen peroxide in the case of OPA) according to the toxicity text. However, with the exception of hydrogen peroxide on latex, it was the most porous test materials, namely latex and cotton, that accumulated the least residue. BNP was the disinfectant that left the least residue on the five test materials, while the greatest residual concentration was left by hydrogen peroxide on latex (as much as 5 microg/cm2). The biotest used in this study permitted the detection of disinfectant residues released by different types of previously disinfected clinical materials, and can be adapted to simulate elution conditions similar to those existing in routine hospital practice.

Biological Assay↗
PubMed1995

General disinfection guidelines.

Cleaning and disinfection of surfaces which have been in contact with animals, poultry or organic material is a vital element in controlling bacterial and viral diseases, and ensuring the wholesomeness and safety of foods. The thoroughness of pre-disinfection cleaning is the most important determinant of the efficacy of disinfection processes. Disinfectant users and officials responsible for the use of disinfectants must have clear goals and a sound plan of action. They must choose appropriate products, properly clean and prepare the site, and take the necessary steps to ensure the safety of animals, humans, equipment and the environment. They must also objectively evaluate the results of disinfection procedures. Safe and effective disinfectant strategies require an understanding of the actions and toxicological hazards of the chosen products, a clear plan of action, regulatory discipline, conscientious documentation, responsible supervision and post-disinfection testing. Disinfection procedures and policies must meet legal and environmental requirements and the changing expectations of society.

Animal Diseases↗
PubMed1995

[Udder disinfection and mastitis in cattle: a literature review].

Postmilking teat disinfection is accepted as an important part of standard preventive measures against mastitis in dairy cattle. The efficacy of postmilking teat disinfection against infections with contagious pathogens such as Staphylococcus aureus and Streptococcus agalactiae is beyond doubt. However, the efficacy of teat disinfection against infections with environmental pathogens such as Escherichia coli is disputed, and a negative effect has even been described in some situations. This article reviews the practice of teat disinfection in dairy cattle. Premilking and postmilking teat disinfection are discussed, as is the efficacy, different ways of teat disinfection, and different disinfectants. It is concluded that post-milking teat disinfection is an effective management measure in most herds. Selection of teat disinfectants should be based on proven efficacy, which is required for registration of the preparation as a veterinary medical product in the Netherlands.

Animals↗
PubMed2005

Possible associations between Salmonella persistence in poultry houses and resistance to commonly used disinfectants and a putative role of mar.

A putative link between Salmonella persistence in the agricultural sector and resistance to disinfectants has been sparsely investigated. Therefore, minimum inhibitory concentration (MIC) tests against five disinfectants commonly used in poultry premises (formaldehyde, glutaraldehyde/benzalkonium chloride compound, oxidising compound, tar oil phenol, iodophor) were performed on 286 Salmonella isolates, including 256 from Danish broiler houses, altogether representing nine serotypes. Six of these isolates were used for adaptation and de-adaptation studies involving the five disinfectants. Amongst 60 of these isolates selected for growth studies in cyclohexane (possibly associated with up-regulated efflux), only one isolate grew. From this isolate and the six isolates used in the adaptation and de-adaptation studies, mutants highly resistant to triclosan (a disinfectant linked with mar-type resistance) were selected. In addition, adaptation and de-adaptation studies with triclosan were performed. For the 286 isolates, the small variations in MICs could not be associated with Salmonella persistence in Danish broiler houses or previous use of relevant disinfectants. Adaptation and de-adaptation did not alter MICs to the five farm disinfectants. Compared to the parent isolates, MICs for the triclosan adapted and de-adapted isolates and the triclosan mutants were significantly increased to triclosan, but not to the five disinfectants. Moreover, most of the triclosan adapted and de-adapted isolates grew in cyclohexane. Thus, there was no correlation between triclosan and cyclohexane resistance on one hand and resistance to the five disinfectants on the other, suggesting that triclosan resistance is not linked with resistance to these disinfectants.

Adaptation, Physiological↗
PubMed2003

Evaluation of virucidal activity of three commercial disinfectants and formic acid using bovine enterovirus type 1 (ECBO virus), mammalian orthoreovirus type 1 and bovine adenovirus type 1.

A modified version of the test method of the Comité Européen de Normalisation (CEN) was developed using formic acid and three commercial disinfectants to evaluate virucidal activity against three non-enveloped viruses, bovine enterovirus type 1 (ECBO virus), mammalian orthoreovirus type 1 and bovine adenovirus type 1 (BAV 1). Determination of the effects of temperature was carried out at 20 and 10 degrees C. All tests with protein load used bovine serum albumin (BSA) and yeast extract. The investigations were performed in suspension tests and in carrier tests using poplar wood virus carriers. The carrier tests showed that ECBO virus could be inactivated at 20 degrees C with 1% formic acid within a 60 min reaction time. For disinfection of ECBO virus at 10 degrees C within 60 min, a 2% concentration of formic acid was necessary. Formic acid was ineffective against reovirus and bovine adenovirus and cannot be recommended as a reference disinfectant. Inactivation of ECBO virus and adenovirus type 1 using a disinfectant containing aldehydes and alcohols could be achieved, but only at room temperature. The disinfection of reovirus type 1 at room temperature with this product was possible without a protein load. This disinfectant exhibited disinfection ability at 10 degrees C at a concentration of more than 2% or with a longer exposure time. A disinfectant containing aldehydes was effective at room temperature but its effect was reduced in the presence of organic matter. Inactivation at 10 degrees C was found only against adenovirus. The fourth disinfectant, which contained peroxiacetic acid, inactivated all test viruses at a concentration of 0.5% within 15 min independent of temperature and protein load.

Animals↗
PubMed2005

Impact of food disinfection on beneficial biothiol contents in vegetables.

In this work we investigated the impact of food disinfection on the beneficial biothiol contents in a suite of vegetables consumed daily, including spinach, green bean, asparagus, cucumber, and red pepper. Four disinfection technologies commonly studied and/or used in food processing and preservation, including hydrogen peroxide, free chlorine, and gaseous- and aqueous-phase ozone, were examined with common dosages and contact times. Results indicate that the common disinfection technologies may result in significant loss of beneficial biothiols in vegetables which are essentially important to human health. For example, as much as 70% of biothiols were lost when spinach was treated with hydrogen peroxide (5.0 wt %) for 30 min. Approximately 48-54% of biothiols were destroyed by free chlorine and gaseous- and aqueous-phase ozone under typical contacting conditions. In red pepper, about 60-71% of reduced glutathione was oxidized by the disinfectants. The potential decrease in biothiols during disinfection was dependent upon the biothiol type, the disinfectant, and the vegetable. The effectiveness of total bacterial inactivation by the four disinfection technologies was concurrently evaluated. Results show that free chlorine is most effective, achieving disinfection efficiencies of greater than 4 log for all study vegetables. This study may provide important information for the food industry to design optimum contacting methods for vegetables to simultaneously achieve sufficient bacterial disinfection while minimizing loss of beneficial biothiols.

Disinfection↗
PubMed2002

Wettability, imbibition, and mass change of disinfected low-viscosity impression materials.

STATEMENT OF PROBLEM: There is an ongoing effort by dental manufacturers to create impression materials with improved wetting properties. Disinfection solutions may alter the surface characteristics of these newer materials. PURPOSE: This study compared wettability, imbibition, and mass change of various recently introduced automixed low-viscosity addition silicone and polyether materials before and after immersion disinfection. MATERIAL AND METHODS: The Wilhelmy technique was used for deriving wetting properties of 5 addition silicone materials (Clinician's Choice Affinity, Clinician's Choice Superhydrophilic [experimental], Kerr's Take One, 3M's Imprint II, and Dentsply's Aquasil LV) and 2 polyether materials (ESPE's Permadyne Garant and Impregum Garant). Conditions included a control with no disinfection (0 hours), as well as (1/2) hour of immersion disinfection in a full-strength solution of 2% acid glutaraldehyde disinfectant (Banicide). Weight changes before and after disinfection and weight loss in air were measured over an 18-hour period to detect imbibition and mass change over time. The data were analyzed with a 1-way analysis of variance at alpha=0.05, with n = 3 for advancing (ACA) and receding (RCA) contact angles and n = 2 for imbibition and mass change. RESULTS: Statistical significant differences in wettability (P<.001) were found among nondisinfection control groups, as well as among (1/2)-hour disinfection groups. Polyethers were the most wettable materials overall. Impregum Garant polyether demonstrated significantly lower RCA for the control (48.4 degrees) and at (1/2) hour of disinfection (51.8 degrees). The 2 polyethers and Take One lost mass, whereas Aquasil LV gained mass in air; however, all materials exhibited some degree of imbibition during disinfection. CONCLUSION: Within the limitations of this study, the 2 polyether materials tested exhibited significantly lower ACA's and RCA's compared with the 5 addition silicones tested. Imbibition for the 2 polyether materials was significantly higher (P<.001). Polyether materials lost significantly more (0.6% to 0.8%) and Aquasil LV gained significantly more (0.6%) mass in air.

Absorption↗
PubMed2006

Comparison of UV C light and chemicals for disinfection of surfaces in hospital isolation units.

OBJECTIVE: To determine the bactericidal effect on surfaces of ceiling- and wall-mounted UV C (UVC) light (wavelength, 254 nm) in isolation units, compared with standard hospital environmental cleaning and chemical disinfection during final disinfection after patients are treated for infections. DESIGN: Microbial samples were obtained from surfaces in isolation units (patient room, anteroom, and bathroom) before and after irradiation with UVC, chloramine disinfection, and standard hospital environmental cleaning. Samples were tested using standard contact plates. SETTING: Four identical, negative air-pressure isolation units (patient room, anteroom, and bathroom) with a defined number of ceiling- and wall-mounted UVC light units. The UVC distribution was monitored in one isolation unit after irradiation for approximately 40 minutes, corresponding to doses ranging from 160 J/m2 in a shadowed area to 19,230 J/m2 at the mostly highly exposed site (which is high enough to inactivate most bacterial organisms, including spores). RESULTS: UVC disinfection significantly reduced the number of bacteria on surfaces directly or indirectly exposed to UVC to a very low number, as did 5% chloramine disinfection alone (P<.001 for both). Completely shadowed areas in the isolation unit (eg, the bed rail, lockers, and mattresses) still required disinfection by chemicals. CONCLUSION: Disinfection with UVC light may significantly reduce environmental bacterial contamination and thereby protect the next patient housed in an isolation room. UVC disinfection may not be used alone but is a good addition to chemical disinfection.

Bacteria↗