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Effectiveness of commercial disinfectants for inactivating hepatitis A virus on agri-food surfaces.

Six commercial disinfectants were tested for their efficacy in inactivating hepatitis A virus in solution or attached to agri-food surfaces. Disinfectant I contains 10% quaternary ammonium plus 5% glutaraldehyde; disinfectant II contains 12% sodium hypochlorite; disinfectant III contains 2.9% dodecylbenzene sulfonic acid plus 16% phosphoric acid; disinfectant IV contains 10% quaternary ammonium; disinfectant V contains 2% iodide; and disinfectant VI contains 2% stabilized chlorine dioxide. Among these, disinfectants I and II were shown to be the most effective in inactivating hepatitis A virus in solution. The efficacy of these disinfectants was further tested against hepatitis A virus attached to common agri-food surfaces, including polyvinyl chlorine, high-density polyethylene, aluminum, stainless steel, and copper. Disinfectant II was shown to be the most effective, with a maximum inactivation level of about 3 log10. The inactivation efficacy was shown to be affected by the concentration of the active ingredient, the contact time between the disinfectant and the contaminated surfaces, and the incubation temperature. In general, hepatitis A virus was shown to be highly resistant to most disinfectants tested, and high concentrations of active ingredient were needed to achieve acceptable inactivation levels.

Bacterial Adhesion↗

[Methods for testing surface disinfection procedures under current conventional conditions].

A method of testing surface disinfection procedures is described with which the same conditions are maintained as those encountered in practice. The disinfectant is applied to surfaces in a conventional manner at a natural scale. A standardised wet-mopping procedure (two-bucket method) applied to floors of glazed clinker serves as a reference. The test method is quantitative. For comparison the same procedure using water of standardised hardness is used. The test parameters are the reduction of the colony count (CC) both on the surface treated and in the used washing water following certain periods of exposure to the disinfectant. For the suitability test of disinfectants the surface is contaminated with reference strains, Kl. pneumoniae ATCC 27736 and Staph. aureus Wood 46. In some special cases wild strains were used for contamination. When testing surface disinfection under user conditions, the flora settling on the surface used is investigated. The bacterial collector after Thran is employed for the extraction of the germs from the surface. Wet mopping with water of standardised hardness has already reduced the count on the floor of Kl. pneumoniae by 2.8 log on average and the count of Staph. aureus by 2.2 log. By the use of the three types of disinfectants tested the count was additionally reduced by 0.45 to 0.72 log for Kl. pneumoniae and by 1.2 to 2.2 log for Staph. aureus. Even after disinfection a spread of germs can be observed; however, it is slight and corresponds to the spread found after the use of water. After mopping with 17 degrees dH water, practically the total germ count applied is found in the cleaning water. After application of the disinfectant the germ counts for Kl. pneumoniae are reduced by 1.8 to 3.7 log and by 3.1 to 3.7 log for Staph. aureus, depending on the type of disinfectant after an exposition of 5 min in the washing water. With respect to Kl. pneumoniae, reduction of the count continues to amount to 2.7 to 3.8 log after 30 min, so that merely 20 to 30 CFU/100 ml washing water remain. The concentration of the disinfectant mainly influences the reduction of germs in the washing water. Thus the analysis of the washing water constitutes an important parameter for the evaluation of a surface disinfectant. The testing procedure proposed is very flexible as it can be readily adapted to the various disinfection problems and evaluation criteria.

Disinfectants↗

[Disinfectant tests at 20 and 10 degrees C to determine the virucidal activity against circoviruses].

To evaluate virucidal activity against porcine circovirus type 2 (PCV2), four disinfectants were tested under laboratory conditions. As basis to perform the testing the "Guidelines for testing chemical disinfectants" of the German Veterinary Association (DVG-guidelines) were applied. For simulation of field conditions, the tests were carried out in virus carrier tests, at 20 and 10 degrees C, and under protein load (40% foetal calf serum (FCS) in virus suspension). For disinfection of PCV2 at 20 degrees C an exposure time of 120 min in 2% Disinfectant 1 (20% glutaraldehyde, 12% 2-propenal, polymer with formaldehyde) or Disinfectant 2 (55% formic acid, 7% glyoxylic acid) was necessary. 1% of Disinfectant 3 (Component 1: Potassium peroxomonosulphate. Component 2: Active detergents) disinfected PCV2 on carriers within 180 min. After a reaction time of 120 min with 1% and 60 min with 2% Disinfectant 4 (21% glutaraldehyde, 17% formaldehyde) there could not be detected any virus. Reduction on effectivity through temperature reduction to 10 degrees C were more significant for aldehyde containing preparations Disinfectant 1 and Disinfectant 4 than for Disinfectant 2 and Disinfectant 3. These losses on effectivity could be corrected through extension of exposure time or increase of concentration.

Animals↗

[Survey of methods of cleaning, decontamination, disinfection and sterilization in dental health services in tropical areas].

The International Aid for Ontology (IAO) carried out this survey of hygiene in the dental health services of 5 French-speaking African countries in 1994, in association with the Faculty of Pharmaceutical and Biological Sciences of Paris. This study received support from the World Health Organization (WHO), the French Ministry for Cooperation and the European Community and the Ivory Coast Oral and Dental Hygiene and Health Committee (CIHSBD). Twenty-nine dental services from Benin (3), Burkina Faso (6), Ivory Coast (12), Mali (5), Niger (3) participated in this survey which gives an insight into the daily hygiene routines of these services. The cleaning, decontamination, disinfection and sterilization procedures for premises, dental equipment, instruments, hands and disposable items were investigated. No individual protocols are reported. Bench tops were cleaned or disinfected daily in 73% of centers and floors were cleaned or disinfected daily in 59% of centers. Walls were cleaned once per week in 44% of the centers. Hands were always washed between patients, with 68% of dental surgeons using only solid or liquid cleansing soaps and the others using antiseptic or disinfectant solutions. The dentist's chair was cleaned or disinfected daily in 68% of centers, mostly with soap (43%) or diluted bleach (23%). Vacuum equipment was cleaned with soap (50%) or diluted bleach (57%), with some surgeries using a combination of the two. Hand pieces and turbines were cleaned and disinfected after each use with alcohol (35%) or diluted bleach (26%) and were sterilized in 9% of centers. Instruments were sterilized with a Poupinel (63%), unspecified sterilizer (26%), autoclave (7%) or low temperature disinfection procedure (4%). Instruments were regularly sterilized in all centers. Single-use disposable items were often reused: 88% of centers reused gloves, 64% anesthetic cartridges and 32% disposable needles. This survey demonstrates that dentists do attempt to achieve appropriate hygiene standards despite difficult practice conditions, exacerbated by supply problems. In all applications, hygiene involves a succession of closely-related, logical steps, which form an asepsis chain aimed at preventing the transmission of infection. Our survey shows that fundamental elements of hygiene require attention to achieve this aim. The cleaning, disinfection and sterilizing of floor surfaces and equipment should be improved and more widespread use made of disposable items. It is important to define the hygiene level required for particular treatments, taking into account the oral and dental micro flora and whether the equipment has been decontaminated, disinfected or sterilized. A piece of equipment is decontaminated if it has been mechanically cleaned and decontaminated. It is disinfected if these steps are followed by rinsing with sterile water, drying and conditioning. An item is described as sterilized if it is cleaned, decontaminated, rinsed, dried, conditioned and then sterilized. We found that a wide variety of chemicals were used to clean hands, surfaces and equipment. The nature and appropriate methods of use of these chemicals were not widely known. Understanding the chemical composition of these chemicals makes it possible to classify them into cleaning agents, detergents, decontaminating agents and disinfectants. The definition, choice and use of antiseptics and disinfectants should be strictly controlled. It is also vital that single-use disposable items are used only once and are never reused. Hygiene in the dental surgery is a chain of processes aimed at protecting the patient and the medical staff. There are many links in the chain, involving floor and surface hygiene, hand washing by dentists and dental assistants, washing of surgery linen and treatment of equipment. Dental practitioners should continually focus on ensuring that the chain of hygiene procedures is not broken, in their own interests as well as in those of their patients.

Benin↗

Peracetic acid (PAA) disinfection of primary, secondary and tertiary treated municipal wastewaters.

The efficiency of peracetic acid (PAA) disinfection against enteric bacteria and viruses in municipal wastewaters was studied in pilot-scale. Disinfection pilot-plant was fed with the primary or secondary effluent of Kuopio municipal wastewater treatment plant or tertiary effluent from the pilot-scale dissolved air flotation (DAF) unit. Disinfectant doses ranged from 2 to 7 mg/l PAA in the secondary and tertiary effluents, and from 5 to 15 mg/l PAA in the primary effluents. Disinfection contact times were 4-27 min. Disinfection of secondary and tertiary effluents with 2-7 mg/l PAA and 27 min contact time achieved around 3 log reductions of total coliforms (TC) and enterococci (EC). PAA disinfection also significantly improved the hygienic quality of the primary effluents: 10-15 mg/l PAA achieved 3-4 log reductions of TC and EC, 5 mg/l PAA resulting in below 2 log reductions. F-RNA coliphages were more resistant against the PAA disinfection and around 1 log reductions of these enteric viruses were typically achieved in the disinfection treatments of the primary, secondary and tertiary effluents. Most of the microbial reductions occurred during the first 4-18 min of contact time, depending on the PAA dose and microorganism. The PAA disinfection efficiency remained relatively constant in the secondary and tertiary effluents, despite of small changes of wastewater quality (COD, SS, turbidity, 253.7 nm transmittance) or temperature. The disinfection efficiency clearly decreased in the primary effluents with substantially higher microbial, organic matter and suspended solids concentrations. The results demonstrated that PAA could be a good alternative disinfection method for elimination of enteric microbes from different wastewaters.

Coliphages↗

Dimensional stability and detail reproduction of irreversible hydrocolloid and elastomeric impressions disinfected by immersion.

STATEMENT OF PROBLEM: Because irreversible hydrocolloid impressions imbibe blood and saliva, immersion rather than spray disinfection may be more effective. Polyether has been shown to be dimensionally sensitive to immersion disinfection. PURPOSE: The aim of this study was to determine whether irreversible hydrocolloid and polyether impressions could be disinfected by immersion without sacrificing accuracy and surface quality. MATERIAL AND METHODS: Impressions were made of a master mandibular arch containing a crown preparation. Changes between the master and working casts were assessed. Irreversible hydrocolloids (Jeltrate; Palgaflex), a polyether (Impregum F), and an addition silicone (President) were used. Disinfectants were an iodophor (Biocide), a glyoxal glutaraldehyde (Impresept de), and a phenol glutaraldehyde (Sporicidin). The control was without disinfection. Casts were formed in Type IV gypsum. The roughness of working dies was also recorded and an analysis of variance was used for statistical evaluation. Results. Casts from disinfected irreversible hydrocolloid and elastomeric impressions maintained accuracy for anteroposterior and cross arch dimensions where differences from the master was less than 0.1%. Buccolingual and mesiodistal dimensions of working dies (disinfected and control) were 6 to 8 microm larger than the master for addition silicones and 11 to 16 pm for polyethers. The occlusogingival dimension of dies for control and disinfected polyether was 9 pm longer than the master compared with -3 microm for addition silicone. The range of mean surface roughness of working dies made from irreversible hydrocolloids was 1.4 to 1.7 microm and ranged from 0.5 to 0.7 microm for elastomeric impressions. Conclusion. Immersion disinfection of Jeltrate material with iodophor and Palgaflex material with glyoxal glutaraldehyde produced casts and dies as accurate as the control. Control and disinfected elastomeric impression produced dies as clinically accurate and smooth as the master. Disinfection of irreversible hydrocolloid impressions with the glyoxal and phenol glutaraldehyde produced a surface smoother than controls.

Alginates↗

Susceptibility of Salmonella isolated from fish feed factories to disinfectants and air-drying at surfaces.

The objective of this work was to determine whether persistence of certain Salmonella isolates in fish feed factories involved enhanced resistance to disinfectants or air-drying. Salmonella isolates known to be persistent in fish feed factories and Salmonella isolates from other origins were tested for their sensitivity to nine disinfectants by using a suspension test. More than 5log(10)reduction in viable count for all isolates was only achieved by two of the disinfectants at 80% of the lowest recommended user concentration. However, Salmonella isolates from fish feed factories were not more resistant to disinfectants compared to Salmonella from other origins. For four of the disinfectants, presence of fish feed had a more adverse effect on disinfection efficacy compared to the protein bovine serum albumin (BSA). In general, the Salmonella isolates were more resistant to disinfection than Escherichia coli DSM 682, a strain recommended in testing of disinfectants. The Salmonella isolates were also tested for their ability to survive air-drying at stainless steel surfaces, but there were no differences in survival of isolates from fish feed factories compared to isolates of other origin. In conclusion the Salmonella isolates from fish feed factories were not particularly resistant to disinfection or air-drying at surfaces. The data show that disinfectants to be used against Salmonella should be thoroughly tested and selected, since not all disinfectants appear to be effective against Salmonella.

Animal Feed↗

Cleaning and disinfection practices in digestive endoscopy in spain: results of a national survey.

BACKGROUND AND STUDY AIMS: Disinfection and surveillance of it are important for ensuring safety in gastrointestinal endoscopy. The aim of this survey was to assess the current status of disinfection in gastrointestinal endoscopy units in Spain. MATERIALS AND METHODS: An anonymous questionnaire on cleaning and disinfection methods was sent to gastrointestinal endoscopy units at 244 public hospitals in Spain. A minimum standard of disinfection (MSD) was defined to evaluate the appropriateness of disinfection practices. RESULTS: A total of 144 centers responded (58 %). All units perform manual washing of endoscopes before disinfection. Automatic washers are available in only 23 % of the centers. Selective cleaning of internal channels is systematically performed in 85 % of the centers. Glutaraldehyde-based disinfectants are the most commonly employed (84 % of units). The time of exposure to the disinfectant is at least 10 min in 97 % of units, but 20 min or more in only 36 % of them. Endoscopic accessories are sterilized in 57 % of centers. The MSD was complied with by 79 % of the units evaluated. Compliance with the MSD was significantly lower in small units (P = 0.0005) performing small numbers of examinations per month. Quality control tests on the efficacy of disinfection methods are conducted at 66 % of the centers. Specialized personnel record disinfection procedures in 85 % of the centers and supervise them in 55 % of the centers. Half of the units have inadequate equipment and facilities. CONCLUSIONS: This survey suggests that cleaning and disinfection practices in gastrointestinal endoscopy units in Spain have improved in recent years, and that there is a good compliance with standard guidelines. Most units should improve their equipment and facilities in order to provide better comfort and safety for patients and staff.

Disinfectants↗

Rates of hand disinfection associated with glove use, patient isolation, and changes between exposure to various body sites.

BACKGROUND: Handwashing is the most effective and economic intervention shown to reduce nosocomial infection rates. However, studies have consistently documented low hand disinfection compliance. Literature regarding the roles that concomitant glove use and isolation precautions play in health care worker compliance with hand disinfection is limited. It is unclear whether workers change gloves and disinfect hands adequately between exposures to different body sites/secretions while caring for a patient. METHODS: This was an observational study in which hand disinfection compliance and glove use among workers was evaluated in 2 intensive care units at a tertiary care hospital. RESULTS: Five hundred eighty-nine opportunities for hand disinfection were recorded in 40 hours of observation. Overall compliance was 22.1%. We found a statistically significant, positive association between glove use and subsequent hand disinfection (relative risk [RR], 3.9 [95% CI, 2.5-6.0]; P <.0001). Isolation precautions did not significantly increase disinfection compliance. Only 4.8% (3/63) of workers appropriately complied with disinfection when hands were exposed to multiple body sites/secretions while caring for a patient. CONCLUSIONS: Glove use increases compliance with hand disinfection. Isolation precautions do not increase compliance. Workers do not appropriately comply with disinfection guidelines when attending to multiple body sites/secretions on the same patient. Compliance with hand disinfection remains low.

Attitude of Health Personnel↗

[Effectiveness of instrument disinfectants under increased protein exposure and for standing times up to two weeks].

To examine the possibility of prolongation of the standing times of instrument disinfectants, in vitro tests under high albumin exposure and tests in clinical practice were done. Concerning in vitro tests: The bactericidal effectiveness of 7 commercial preparations for instrument disinfection with different basic substances was determined in quantitative suspension tests and of 8 preparations in practice-oriented tests according to the guidelines for testing and approval of instrument disinfectants by the DGHM (German Society for Hygiene and Microbiology). Tests were carried out under increased albumin exposure and at prolonged standing times up to 12 days. The instrument disinfectants showed microbicidal efficacy up to 12 days at working concentrations slightly increased in relation to the concentrations listed by the DGHM. Concerning tests in clinical practice: In 4 clinical wards (intensive care unit, cystoscopy unit, urological operation unit, gastroenterological endoscopy unit with ERPC) the preparations for instrument disinfection were tested up to 12 days in respect to the protein exposure and the disinfecting activity of the working solution. The working solution was not renewed during the 12 days. The inserted instruments were recorded. Concentration of the disinfectants and the protein concentration were daily determined. Disinfecting activity was examined by practice-oriented microbiological tests. The highest protein exposure was 0.098% after a standing time of 12 days. A loss in concentration of disinfectants could not be found. Nevertheless independent from the protein exposure there was a loss in disinfecting activity of the tap water diluted specimens from the clinical practice. Loss in activity could not be seen in the specimen from laboratory parallel tests, which were diluted by water of standard hardness. The loss in disinfecting activity of the tap water diluted preparation from the gastroenterological endoscopy unit versus a dilution by water of standard hardness could be confirmed in control experiments (practice-oriented tests with S. aureus over a period of 5 days).

Albumins↗

Disinfection of fabrics and carpets artificially contaminated with calicivirus: relevance in institutional and healthcare centres.

Fabrics and carpets are used widely as surface coverings or linens in healthcare settings and are prone to contamination with infectious agents such as noroviruses (NoVs). Laundering, water cleaning and vacuuming are considered to be adequate for routine cleaning of these materials, but no standard procedure for their disinfection is available in case of contamination. Testing disinfectants for their efficacy against NoVs is difficult because these viruses cannot be cultivated in vitro. Therefore, feline calicivirus (FCV) has gained acceptance as a surrogate model for NoVs in disinfectant efficacy testing. The present study evaluated five disinfectants against FCV on various fabrics or carpets. FCV was dried on fabrics and carpets, followed by treatment with a given disinfectant for a defined contact time of 1, 5 or 10 min. The surviving virus was then eluted and titrated in Crandell-Reese feline kidney cells to determine virus inactivation. A disinfectant was considered to be effective if it inactivated at least 99% of the applied virus. Metricide, an activated dialdehyde-based product, was found to be the most effective disinfectant on all types of fabric and carpet, inactivating more than 99.99% of the virus in 1-10 min. In general, effectiveness of disinfectants increased with an increase in exposure time from 1 to 10 min. The disinfection of carpets was more difficult than the disinfection of fabrics; 100% polyester was the least amenable to disinfection. Only Metricide and Microbac-II (a phenolic compound) were able to inactivate 99% of FCV on 100% polyester. In summary, activated dialdehyde was found to be uniformly active against FCV on all types of material tested.

Animals↗

Disinfection of tonometers and contact lenses in the office setting: are current techniques adequate?

PURPOSE: To determine whether routine office techniques used to disinfect tonometer prisms and trial contact lenses are sufficient to prevent transmission of ocular infections. METHOD: We reviewed the current literature on the efficacy of certain disinfection protocols against commonly encountered viral, bacterial, and fungal pathogens as well as Acanthamoeba. RESULTS: Some commonly used disinfecting solutions and techniques may be inadequate for disinfection of viruses such as hepatitis C virus and organisms such as Acanthamoeba. When used in accordance with guidelines published by the United States Centers for Disease Control and Prevention (CDC) and the American Academy of Ophthalmology (AAO), 3% hydrogen peroxide is a very effective disinfectant against a wide variety of microorganisms. Specifically, tonometer prisms disinfected by a 5-minute soak in 3% hydrogen peroxide (or 70% isopropyl alcohol or a 1:10 dilution of sodium hypochlorite) are adequately disinfected against most ocular pathogens, with the exception of Acanthamoeba. Trial contact lenses that are disinfected with a 2-hour soak in 3% hydrogen peroxide are effectively rid of all pathogens of concern. After disinfection, rigid lenses should be stored dry, and soft lenses should be stored in a sterile, preserved solution. Repeat disinfection should be routinely performed at 1-month intervals to prevent regrowth of organisms. CONCLUSION: A safe office environment can be maintained by following current CDC recommendations for disinfection, as well as instituting some additional procedures.

Anti-Infective Agents↗

Effects of biofilm formation on haemodialysis monitor disinfection.

BACKGROUND: Biofilms are composed of communities of micro-organisms adhering to essentially any surface. We evaluated whether biofilm formation in the hydraulic circuit of a purposely contaminated haemodialysis monitor would modify the efficacy of different disinfection modalities against bacteria and endotoxin concentrations. METHODS: A water-borne Pseudomonas aeruginosa (109) suspension was recirculated for 1 h and was left standing for 72 h (stationary phase) in the hydraulic circuit of the monitor. The monitor was then washed and disinfected by different physical (heat, 85 degrees C) or chemical (hypochlorite or peracetic acid) disinfection modalities (protocol A). In protocol B, the bacterial suspension was also recirculated for 1 h, but the monitor was then immediately washed and disinfected by different chemical disinfection modalities (hypochlorite or peracetic acid). RESULTS: Biofilm formation was revealed by scanning and confocal laser electron microscopy after the stationary phase (protocol A), but was absent when the monitor was immediately washed and disinfected (protocol B). In the presence of biofilm (protocol A), heat in association with citric acid was the most effective modality for reducing both colony forming units and endotoxin concentrations, whereas heat by itself was the least effective method of disinfection. Dwelling (60 h) with diluted peracetic acid completely prevented the formation of biofilm. In the absence of biofilm (protocol B), chemical disinfection proved to be effective against both colony forming units and endotoxin concentrations. CONCLUSIONS: We found that biofilm formation may markedly reduce the efficacy of presently available disinfection modalities. Therefore, different disinfection modalities and the combined action of descaling (by citric acid) and disinfection (physical/chemical agents) should be used periodically in haemodialysis monitors. In addition, dwelling with diluted peracetic acid should be adopted whenever monitors are not in use.

Bacterial Infections↗

Comparison of static and dynamic disinfection models for bacteria and viruses in water of varying quality.

Disinfection studies rarely use natural waters due to demands exerted on the applied disinfectants and lack of consistent disinfectant residuals. This study compared the degree of disinfection achieved in natural waters between conventional batch (static) models and a system of similar volume where disinfectant residuals were maintained at constant levels (dynamic). In the latter, disinfectant was delivered through a hollow fibre cartridge from a slipstream of a full-scale (chloramine) or pilot (chlorine) water treatment plant. The test organisms (hepatitis A virus, poliovirus, MS-2, Mycobacterium terrae and Enterococcus durans) were selected with different resistance to the disinfectants. In general, for water of "good" quality, the differences between the two systems were often small or not apparent for monochloramine. However, for low chlorine residuals, or when additional demand was placed on the disinfectant, differences between the two systems became more apparent. Little difference was seen between disinfection of the test organisms singly or in mixtures, but injury of vegetative bacteria with monochloramine was very apparent. This system could be useful for understanding the fluctuations in disinfection efficacy that may occur in source water of varying quality, or in distribution systems, as disinfectant residuals decline.

Chlorine↗

Disinfection kinetics of Legionella pneumophila by ultraviolet irradiation.

Disinfection kinetics of Legionella pneumophila by ultraviolet irradiation was investigated. The change in viable cell concentration with exposure time could be divided into three steps: lag step in which little change in viable cell concentration was observed, fast disinfection step and slow disinfection step. The slow disinfection step was not observed at the initial cell concentrations below about 10(6) cfu/mL. The disinfection kinetics were well described with two parameters; lag time and disinfection rate constant of the fast disinfection step. The effects of UV intensity, temperature and initial cell concentration in the kinetic parameters were investigated. With increasing initial cell concentration, the lag time decreased and the disinfection rate constant increased. The effects of initial cell concentration on the kinetic parameters were considered to be attributed to the decrease in the effective UV irradiation intensity due to the partial shield of UV light by the disinfected cells. The empirical correlations were presented for predicting the lag time and disinfection rate constant. Furthermore, UV disinfection of L. pneuophila in a model hot-tub connected with external irradiation chamber was also discussed.

Disinfection↗

The effect of a range of disinfectants on the dimensional accuracy of some impression materials.

In this study the dimensional accuracy of two model materials; dental stone and plaster of Paris, reproduced from three commonly used impression materials; alginate, polyether and addition-cured silicone, retained by their adhesives in acrylic resin trays and exposed to four disinfectant solutions was evaluated. Ninety casts were used to investigate the effect of the four disinfectants on the dimensional accuracy of alginate, polyether and addition-cured silicone impression material. For each impression material 30 impressions were taken, half were poured in dental stone and half in plaster of Paris. The disinfectants used were Dimenol, Perform-ID, MD-520, and Haz-tabs. Measurements were carried out using a High Precision Reflex Microscope. For the alginate impressions only those disinfected by 5-minute immersion in Haz-tabs solution and in full-strength MD 520 were not adversely affected by the disinfection treatment. All polyether impressions subjected to immersion disinfection exhibited a clinically acceptable expansion. Disinfected addition-cured silicone impressions produced very accurate stone casts. Those disinfected by spraying with fill-strength Dimenol produced casts that were very similar to those left as controls, but those treated by immersion disinfection exhibited negligible and clinically acceptable expansion. The results of the studied demonstrated that the various disinfection treatments had different effects on the impression materials. It is important that an appropriate disinfectant is used for each type of impression material.

2-Propanol↗

[Study on the resistance of Escherichia coli O157:H7 to disinfectants in relationship with its plasmid pO157 and chromosome DNA].

OBJECTIVE: To study the change of Escherichia coli O157:H7 resistance to disinfectants in continuous disinfection and the relationship between the resistance and pO157, chromosome DNA. METHODS: Using 4 disinfectants in a separate manner to disinfect 5 Escherichia coli O157:H7 50 generations continuously, we made a before-after comparison of their resistibility and analyzed the change of the structure of pO157 and chromosome DNA. RESULTS: After the 50-generation-continuous disinfection, the bacteria resistance to sodium dichloroisocyanurate, iodophor and quaternary ammonium increased, but the resistance to chlorhexidiniacetas did not any change; the maps Cal I and Rsr II cutting pO157 revealed some changed after disinfection by sodium dichloroisocyanurate and quaternary ammonium, but the maps showed no change after disinfection by iodophor and chlorhexidiniacetas; the chromosome DNA PFGE maps change considerably after 50 generations of disinfection by sodium dichloroisocyanurate, iodophor and quaternary ammonium, but the chromosome DNA PFGE maps were similar after 50 generation of disinfection by chlorhexidiniacetas. CONCLUSION: The Escherichia coli O157:H7 resistance to disinfectants will increase after the 50-generation-continuous disinfection by sodium dichloroisocyanurate, iodophor and quaternary ammonium. There may be genes both in chromosome DNA and in pO157 which resist sodium dichloroisocyanurate and quaternary ammonium, the reason for increase of resistance may be related with the change of chromosome DNA and pO157. There may be genes in chromosome DNA which resist iodophor, the reason for increase of resistance to iodophor may be related with the change of chromosome DNA, but not related with pO157.

DNA, Bacterial↗

Defining unnecessary disinfection procedures for single-dose and multiple-dose vials.

BACKGROUND: Recommendations in the literature conflict on the necessity of disinfecting single-use vials prior to aspiration of fluid. Interventions to disinfect the stopper surface on multiple-dose vials vary considerably. OBJECTIVES: To determine the necessity of alcohol disinfection of the stopper on single-dose vials and to compare povidone-iodine and alcohol versus alcohol-only disinfection of the stopper prior to each needle penetration on multiple-dose vials. METHODS: The rubber stopper surfaces of 100 single-dose vials were cultured for the presence of bacteria. To determine the efficacy of two procedures for disinfection of multiple-dose vials, 87 stopper surfaces routinely disinfected with both povidone-iodine and alcohol were cultured for bacteria. After a change in practice, 100 multiple-dose vials routinely disinfected with alcohol only were cultured for the presence of bacteria. RESULTS: Of the cultures done on single-dose vial stoppers, 99% were sterile. A comparison of the two disinfection techniques for multiple-dose vials revealed that 83 (95%) of the 87 vials prepped with both povidone-iodine and alcohol were sterile, compared with all stoppers disinfected with alcohol only. CONCLUSIONS: This study shows the lack of necessity of any disinfection procedure on the rubber stopper of single-dose vials and the efficacy of alcohol only for disinfecting the stopper of multiple-dose vials.

1-Propanol↗