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[Fiberoptic bronchoscope disinfection with glutaraldehyde phenolate in 1:8 solution].

We evaluated the efficacy of phenolated glutaraldehyde in a 1:8 solution for the disinfection of bronchofibroscopes that were highly contaminated with Serratia marcescens and Pseudomonas aeruginosa. An Olympus BF-P10 bronchofibroscope was contaminated with artificial samples containing one of the aforementioned microorganisms in concentrations nearing 10(8) colony forming units per milliliter (cfu/ml). The instruments were then washed with soap and water and submerged in a 1:8 solution of phenolated glutaraldehyde. Samples were taken for culturing after contamination, after washing, and after 10, 15 and 30 min in the disinfectant solution. The level of cfu/ml in the cultures was measured and the definition of failure-to-disinfect was a finding of > or = 1 cfu/ml after each experimental procedure. Twenty procedures, 10 for each microorganism, were carried out. Washing of the bronchofibroscope afforded significant elimination of microorganisms and no colony growth was observed in cultures after 10 min submersion in phenolated glutaraldehyde. We conclude that immersion in a 1:8 solution of phenolated glutaraldehyde after careful washing is a valid way to disinfect bronchofibroscopes that are highly contaminated with S. marcescens and P. aeruginosa.

Bronchoscopes↗

Disinfectant susceptibility testing of avian and swine Campylobacter isolates by a filtration method.

The susceptibility testing of disinfectants against Campylobacter jejuni and Campylobacter coli strains from broilers and pigs was investigated. The filtration method European standard EN 1040 was adapted to Campylobacter cultures and validated with reference strains. Two disinfectants were tested: 1% benzalkonium chloride active matter, as quaternary ammonium compound, and 0.63% sodium hypochlorite as chlorine-releasing agent. Both disinfectants were effective against the 34 Campylobacter strains tested after 5 min exposure under in vitro conditions. No link between resistance to disinfectants and antibiotics could be observed.

Animals↗

Evaluation of disinfection and sterilization of reusable angioscopes with the duck hepatitis B model.

PURPOSE: Nosocomial transmission of viral hepatitis and retrovirus infection has been reported. The expected risk is greatest for the hepatitis B virus (HBV). The duck HBV (DHBV) has similar biologic and structural characteristics to HBV and has been adopted as a suitable model for disinfectant testing. METHODS: Angioscopic examination of the external jugular vein was performed on DHBV-infected ducks. After use, the instrument was air dried for 3 minutes. Samples were obtained by flushing the channel with 5 mL of phosphate buffered saline solution. The samples were collected immediately after drying (control), after flushing with 5 mL of water, after glutaraldehyde disinfection for 5, 10, and 20 minutes, and after ethylene oxide gas sterilization. Angioscopes were either precleaned or uncleaned before disinfection/sterilization. Residual infectivity was assessed with inoculation of samples into the peritoneal cavity of day-old ducks (n = 231). RESULTS: DNA analysis results of liver samples showed that all 38 control ducks became infected. The frequency of DHBV infection was reduced to 93% (14 of 15) by flushing the angioscope with 5 mL of sterile water. No transmission occurred after the use of any of the properly precleaned and disinfected/sterilized angioscopes. However, after the use of the uncleaned angioscopes, the transmission rate was 90% (9 of 10) and 70% (7 of 10) after 5 and 10 minutes of contact time, respectively, in 2% glutaraldehyde. Even after the recommended 20 minutes of contact time, there was still 6% (2 of 35) transmission. After ethylene oxide sterilization, two of the recipient ducklings (2 of 35) were infected with DHBV. CONCLUSION: There was no disease transmission after reuse of disposable angioscopes adequately cleaned before disinfection or sterilization. However, if the angioscopes are inadequately cleaned, DHBV can survive despite glutaraldehyde disinfection or ethylene oxide sterilization. This contrasts with previous in vitro and in vivo data with solid surgical instruments. It is postulated that the presence of a narrow lumen or residual protein shielding within the lumen may compromise effective inactivation of hepadnaviruses on angioscopes, with the potential risk for patient-to-patient transmission.

Angioscopes↗

Thermal composting of faecal matter as treatment and possible disinfection method--laboratory-scale and pilot-scale studies.

When using toilets where the urine and faeces are collected separately for reuse as nutrients in agriculture, the collected matter should be disinfected. One way to do this is by thermal composting. Composting of different material mixes was investigated in a laboratory-scale experiment. This showed that the best mixture for dry thermal composting was a mix of faeces, food waste and amendment. The urine was collected separately by use of urine-diverting toilets. A new method was developed to mathematically evaluate and estimate the safety margins of pathogen inactivation during thermal composting. The method is based upon a mathematical calculation of the number of times total inactivation (at least 12log(10) reduction) of the organisms is achieved. In a pilot-scale experiment, the disinfection of a faeces/food waste mix was performed with a calculated safety margin of more than 37 times the total die-off of Enteroviruses and some 550 times that of Ascaris. Thus, well functioning composting seems to be effective for disinfection of faecal matter. To get a high temperature in all of the material, the reactor has to have sufficient insulation. A major disadvantage is the initial need for handling the raw un-disinfected material. The degradation of the organic matter in the compost was almost 75%, resulting in a small final volume that could safely be recycled.

Animals↗

Failure of hand disinfection with frequent hand washing: a need for prolonged field studies.

In a prolonged field trial a 4% chlorhexidine digluconate detergent scrub (Hibiscrub(R)), that had earlier proved to be an effective hand disinfectant, was studied in hospital wards. Finger tips were found to harbour more bacteria than the hand dorsum and the samples collected from them yielded more information on the bacteriological and dermatological effects of hand disinfectants in practice.In wards with a relatively low hand-washing frequency (less than 20 times in 8 hours) the bacteriological results resembled those obtained by in-use tests with volunteers. In the neonatal unit where the hand washing frequency was remarkably high, even occasionally over 100 times/8 h shift, an increase in the bacterial colony counts of the majority of the staff was recorded both before and after hand washing already after using the preparation for 1 week. Age, occupation and hand-washing frequency all correlated with the bacteriological results. Twenty-seven out of 37 persons complained of side effects such as wounds of finger tips and redness or heavy drying of the skin. Wounds, particularly on finger tips, resulted in the failure of disinfection. An increase in bacterial counts was sometimes noted without any dermatological or subjective changes. Drying of the skin was complained of less often when no increase in skin bacteria occurred.After the changeover of washing practice to a detergent followed by a rinse with spirit solution containing chlorhexidine and glycerol a decrease was recorded in the bacterial counts. It is concluded that more attention should be paid to long-term testing of hand washing and disinfection methods to ensure optimum final results in practice. It is obvious that the knowledge obtained from short time in-use testing cannot be applied to all conditions of use.

Adult↗

The relative effectiveness of commonly used disinfectants in inactivation of echovirus 11.

Echovirus 11 in the presence of fetal calf serum was exposed to six commonly used disinfectants for times of 10, 20 and 30 s. At the end of such exposure times, skim milk neutralized disinfectant activity and residual virus was assayed using the plaque technique. The six disinfectants studied were Javex, sodium hydroxide, ethanol, Wescodyne, One Stroke Ves-Phene, and Sonacide. Although 0.25% (w/v) sodium hydroxide and 95% (v/v) ethanol were equally virucidal and significantly more so than the other four disinfectants, causing 10(6) reduction in 20 s, they may not be practical to use in many instances. Javex at a dilution of 1/50 (1200 parts/10(6) chlorine) proved to be virucidal causing 10(3.5) reduction of echovirus 11 in 30 s. Wescodyne (1/50) and undiluted Sonacide were relatively ineffective causing 10 reduction or less of echovirus 11 in 30 s. One Stroke Ves-Phene (1/50) was ineffective causing no significant inactivation in 30 s.

Disinfectants↗

A bacteriological investigation of two leisure centre swimming pools disinfected with ozone.

A bacteriological study was carried out on the first Leisure Centre swimming pools in the United Kingdom to be disinfected with ozone/chlorine. Results suggested that a free chlorine concentration of approximately 0.8 mg/l was necessary to maintain the pools in a bacteriologically satisfactory condition. This amount of free chlorine was similar to that required when the pool was disinfected with chlorine alone. However, the associated amount of combined chlorine was much lower when disinfection was by ozone/chlorine and this gave more acceptable bathing conditions. Implications for the manamgement of pools disinfected by this method are discussed.

Chlorine↗

Evaluation of disinfectants in the domestic environment under 'in use' conditions.

An 'in use' test was developed to investigate effectiveness of disinfectant application and of detergent of hot water cleaning at kitchen, bathroom and toilet sites in the domestic environment. Detergent and hot water cleaning produced no observable reduction in microbial contamination. Single and daily application tests demonstrated that hypochlorite and phenolic disinfectants can be used to produce substantial reductions in bacterial contamination in the home. Results indicate that maximum protection afforded by disinfection is relatively brief; 3-6 h after disinfection, contamination levels were only marginally less than those observed at pretreatment. Some suggestions are made for improvements in home hygiene.

Bedding and Linens↗

Chemical disinfection of human rotavirus-contaminated inanimate surfaces.

Fomites may play a role in the transmission of rotavirus infections, and in view of this, 27 disinfectants were evaluated for their ability to inactivate human rotavirus (HRV) on contaminated non-porous inanimate surfaces. Disks of stainless steel, glass and two types of plastics were contaminated with about 10(7) plaque-forming units of HRV suspended in faecal matter. The inoculum was allowed to dry and an equal volume of the product under test was applied to the contaminated surface. After contact for 1 min, the action of the disinfectant was stopped by dilution. Surviving infectious virus on the disks was determined by plaque assay in MA-104 cells. A product was considered to be effective if it could reduce the virus titre by at least 3 log10. Only 33.3% (9/27) of the formulations tested proved to be effective. Further testing of the effective products, which included antiseptics, instrument soaks and hard-surface disinfectants, showed that all of them could, in fact, reduce the virus titre on contaminated surfaces by at least 6 log10. These findings show the relative resistance of HRV to a wide range of chemical disinfectants in common use, and also emphasize the need for a more thorough evaluation of the virucidal potential of formulations regularly employed in attempts to prevent and control outbreaks of rotaviral diarrhoea.

Disinfectants↗

A new synergized glutaraldehyde-phenate sterilizing solution and concentrated disinfectant.

Research leading to the development of Sporicidin, a new (synergized glutaraldehyde-phenate) sterilant and concentrated disinfectant, is reported. Microbial evaluation and shelf life testing of the new formulation was done using AOAC tests--Use-Dilution, Sporicidal, Tuberculocidal--and the E.P.A. Virucidal Test. Full-strength Sporicidin sterilizes (is sporicidal) in 6 3/4 hours at both 20C and 25C, and disinfects in 1-2 minutes. When diluted with 15 parts of tap water, Sporicidin is tuberculocidal, virucidal, and germicidal in 10 minutes, qualifying as a hospital disinfectant that will not "yellow" the hands or skin. The shelf life of activated Sporidicin, full strength or diluted 1 in 16, is 30 days. According to the data presented, which were the basis of E.P.A. registrations, Sporicidin is: (a) the fastest glutaraldehyde sterilant at room temperature, and (b) the only glutaraldehyde product that can be diluted below 2% and still qualify as a hospital disinfectant.

Aldehydes↗

Direct determination of peracetic acid, hydrogen peroxide, and acetic acid in disinfectant solutions by far-ultraviolet absorption spectroscopy.

In this paper we propose a rapid and highly selective far-ultraviolet (FUV) spectroscopic method for the simultaneous determination of peracetic acid (PAA), hydrogen peroxide, and acetic acid (AA). For this purpose we developed a novel FUV spectrometer that enables us to measure the spectra down to 180 nm. Direct determination of PAA, H(2)O(2), and AA, the three main species in disinfectant solutions, was carried out by using their absorption bands in the 180-220-nm region. The proposed method does not require any reagents or catalysts, a calibration standard, and a complicated procedure for the analysis. The only preparation procedure requested is a dilution of H(2)O(2) with pure water to a concentration range lower than 0.2 wt % in the sample solutions. Usually, the required concentration range can be obtained by the 10 times volume dilution of the actual disinfectant solutions. As the measured sample does not leave any impurity for the disinfection, it can be reused completely by using a circulation system. The detection limit for PAA of the new FUV spectrometer was evaluated to be 0.002 wt %, and the dynamic ranges of the measured concentrations were from 0 to 0.05 wt %, from 0 to 0.2 wt %, and from 0 to 0.2 wt % for PAA, H(2)O(2), and AA, respectively. The response time for the simultaneous determination of the three species is 30 s, and the analysis is applicable even to the flowing samples. This method may become a novel approach for the continuous monitoring of PAA in disinfectant solutions on the process of sterilization.

Acetic Acid↗

Evidence that monochloramine disinfectant could lead to elevated Pb levels in drinking water.

Many water districts have recently shifted from free chlorine (in the form of HOCl/OCl-) to monochloramine (NH2-Cl) as a disinfectant for drinking water to lower the concentration of chlorinated hydrocarbon byproducts in the water. There is concern that the use of NH2Cl disinfectant may lead to higher Pb levels in drinking water. In this study, the electrochemical quartz crystal microbalance is used to compare the effects of these two disinfectants on the dissolution of Pb films. A 0.5 microm thick Pb film nearly completely dissolves in a NH2Cl solution, but it is passivated in a HOCl/OCl- solution. X-ray diffraction analysis shows that the NH2Cl oxidizes Pb to Pb(II) species such as Pb3-(OH)2(CO3)2, whereas the stronger oxidant, HOCl/OCl-, oxidizes Pb to Pb(IV) as an insoluble PbO2 conversion coating. Although NH2Cl may produce less halogenated organic byproducts than HOCl/OCl- when used as a disinfectant, it may lead to increased Pb levels in drinking water.

Chloramines↗

A test for cleaning and disinfection processes in a washer-disinfector.

Disinfection processes such as heat, aldehydes or alcohols kill vegetative microorganisms but do not necessarily remove other organic contamination. Organic residues impair the result of low-temperature sterilisation processes. Heat-stable organic residues may give rise to clinical symptoms in the patient. Standards are available in Britain and in Sweden for the examination of cleaning processes in washer-disinfectors. The test substances are artificial soil or blood. These standards are based on visual inspection of instruments or equipment. They cannot be used for examination of tubular instruments, nor can they be quantified. For validation of cleaning procedures a simple quantifiable method, which can be performed in an infection control laboratory is needed. We have used suspensions in horse blood of Enterococcus faecalis bacteria and Bacillus subtilis spores to test disinfection and cleaning in a washer-disinfector. Instruments used for laparoscopic surgery were contaminated with a blood bacteria suspension containing 10(7) organisms/ml and then dried and processed in a washer-disinfector using a regular process. Remaining microbial contamination was cultured quantitatively. Nineteen objects were investigated in 10 experiments each. Cleaning, measured as log reduction >5-6 of B. subtilis, was achieved on surfaces that were adequately in contact with the water flow in the machine. Disinfection (and cleaning) measured as log reduction >5-6 of E. faecalis was successful at all points examined. The test method is simple and quantifiable, and can be used to evaluate and to improve cleaning and disinfection processes.

Animals↗

Antiviral activity of alcohol for surface disinfection.

Bacteria and viruses from the patient's mouth travel with dental splatter and spills. A surface disinfectant should possess antiviral activity as well as antibacterial action. Because of frequent and 'open' application in the dental office, such a disinfectant should be non-toxic, non-allergenic and safe for the hygienist. It now appears that high-concentration alcohol mixtures (i.e. 80% ethanol + 5% isopropanol) are not only excellent antibacterials, but quickly inactivate HIV as well as hepatitis B and hepatitis C viruses. Compared to alternative surface disinfectants, use of high-concentration alcohol for the spray-wipe-spray method of surface disinfection in dentistry appears safe and efficient. However, dried matter should be wiped and hydrated first.

Anti-Bacterial Agents↗

Disinfection of contact lenses without tap water rinsing: is it effective?

PURPOSE: To establish the efficacy of the two most popular contact lens disinfecting systems--one-step hydrogen peroxide and multipurpose disinfecting solution--for 1 month's use in practice in the absence of tap water rinsing. METHODS: This was a descriptive, prospective microbiological study of contact lens contamination with ideal hygiene compliance and new lenses and storage cases. One hundred and fifty contact lens wearers were instructed to avoid risk factors identified for Acanthamoeba infection. They were randomly assigned to use one of three disinfecting systems and taught to follow manufacturers' instructions. In addition, they were taught to avoid all use of tap water for contact lens hygiene, except for hand washing. RESULTS: There was no isolation of Acanthamoeba from any lens storage case, precluding the chance of amoebic infection. The multi-purpose solution gave the lowest rate of bacterial contamination, with 78% sterility and 15% of cases with < 10(4) bacteria/ml. For both one-step peroxide and multi-purpose solutions, Gram-negative bacteria were reduced in frequency compared with values expected historically, while Bacillus sp. were found more frequently. Storage cases of both one-step peroxide systems leaked fluid. CONCLUSIONS: On the basis of contamination in previous studies, when hydrogen peroxide and other chemical disinfectants were used together with tap water washing, it was expected that approximately 40% of lens storage cases would yield bacteria, often with a high count, and that up to 8% would yield Acanthamoeba. Such contamination did not occur, however, in this study. The multipurpose solution, for 1 month's use, gave the lowest rate of bacterial contamination with only 7% of storage cases harbouring bacteria at > 10(4)/ml and with 78% sterility. One of the two one-step hydrogen peroxide systems performed equally well. Importantly, Acanthamoeba was not isolated from any of the 150 storage cases. Whether lens storage cases need to be sterile or contain < 10(3) bacteria/ml solution within them is debatable, but it is essential that Acanthamoeba be absent from them.

Acanthamoeba↗

Peroxidase enzyme sensor for on-line monitoring of disinfection processes in the food industry.

For desirable environmental reasons, peroxides have replaced halogenated substances for disinfection purposes in the food and beverage industry. However, cost issues and the requirement to remove these agents completely after disinfection necessitate simple, low-cost and sensitive test methods with a wide dynamic range and on-line capability. The development and performance of such a method is detailed here. Low-cost peroxide sensors were fabricated using a single deposition procedure, in which horseradish peroxidase enzyme and dimethylferrocene mediator were entrapped within a cellulose acetate membrane, over the working electrode area of a screen-printed three-electrode assembly. Optimum performance was obtained using HRP and DMFc loadings of 25 U and 0.03 micromol per electrode, respectively, and a mean cellulose acetate molecular weight of 37,000. The device had a detection limit of 49.5 microM hydrogen peroxide and mean RSD values of 21% across the concentration range 49.5-368 microM. In laboratory studies the sensor was shown to have a stability of > or = 4 d in continuous flow-mode maintaining an accuracy of +/- 16% that was considered acceptable for the intended on-line monitoring of the disinfection process. In a field study, it was successfully used on-line within a flow-cell to measure peroxide levels during disinfection of an industrial fermentation vessel.

Biosensing Techniques↗

The dimensional stability of self-disinfecting alginate impressions compared to various immersion regimes.

Alginate impressions of a master acrylic study model pair were made in order to assess the effect of various disinfection techniques on dimensional stability. Impressions were made using self-disinfecting alginate, traditional alginate which had been dipped or soaked in a disinfecting solution, and included was a control group which was not disinfected. Inter- and intra-arch linear measurements of the resultant study casts were made using a Reflex Metrograph. The small differences found for the variables measured were not statistically significant.

Alginates↗

In vitro susceptibility of Candida albicans to four disinfectants and their combinations.

AIM: The aim of this study was to evaluate the susceptibility of seven strains of Candida albicans to four disinfectants: iodine potassium iodide, chlorhexidine acetate, sodium hypochlorite and calcium hydroxide. In addition, all possible pairs of the disinfectants were tested in order to compare the effect of the combination and its components. METHODOLOGY: Filter paper discs were immersed in standardized yeast suspensions and then transferred to disinfectant solutions of different concentrations and incubated at 37 degrees C for 30 s, 5 min, 1 h and 24 h. After incubation the filter paper discs were transferred to vials with PBS and glass beads that were then vigorously shaken for dispersal of the yeast cells. PBS with resuspended yeasts was serially diluted 10-fold. Droplets of 25 microL from each dilution were inoculated on TSB agar plates and incubated in air at 37 degrees C for 24 h. The number of colony-forming units was then calculated from appropriate dilutions. RESULTS: C. albicans cells were highly resistant to calcium hydroxide. Sodium hypochlorite (5% and 0.5%) and iodine (2%) potassium iodide (4%) killed all yeast cells within 30 s, whilst chlorhexidine acetate (0.5%) showed complete killing after 5 min. Combinations of disinfectants were equally or less effective than the more effective component. All C. albicans strains tested showed similar susceptibility to the medicaments tested. CONCLUSIONS: This study indicates that sodium hypochlorite, iodine potassium iodide and chlorhexidine acetate are more effective than calcium hydroxide against C. albicans in vitro. However, combining calcium hydroxide with sodium hypochlorite or chlorhexidine may provide a wide-spectrum antimicrobial preparation with a long-lasting effect.

Calcium Hydroxide↗