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PubMed2004

A between-patient disinfection method to control water line contamination and biofilm inside dental units.

The aim of the present study was to evaluate the efficacy of a between-patient disinfection procedures to maintain low bacterial counts in dental unit water line (DUWL) effluents, and control dental water line biofilms. Six dental units already in use, that had never been cleaned, were monitored for three weeks. During the first week only baseline contamination levels were assessed with no treatment of the system. In the second week lines were flushed with water for 30 s before treating each patient. During the third week, a disinfection procedure with 0.26% peracetic acid, followed by a water flush, was implemented before treating each patient. DUWL samples were collected both at the beginning and at the end of 216 dental procedures (72 during each period), plated on R2A agar and incubated at room temperature for seven days to obtain total bacterial counts in colony forming units per millilitre. To assess biofilm control, nine dental units (five never used and four old dental units with established biofilm) were used for 30 days in routine dental practice undergoing five between-patient DUWL disinfecting cycles every day. Water line samples were removed at baseline and at the end of the study and examined by scanning electron microscopy to determine the presence or absence of biofilms. A significant difference (P < 0.01) in mean DUWL bacterial counts was found between the three sets of observations. Biofilms were not present in any of the new dental units and a demonstrable reduction in the biofilms from the four dental units with previous presence of established biofilms was observed at the end of the study. In this study, a between-patient disinfection procedure consisting of flushing DUWL with peracetic acid with use of water was efficacious in the control of both microbial contamination of dental treatment water and dental water line biofilms.

Biofilms↗

PubMed2007

Comparison of 5.25% sodium hypochlorite, MTAD, and 2% chlorhexidine in the rapid disinfection of polycaprolactone-based root canal filling material.

The purpose of this investigation was to compare the effectiveness of 5.25% sodium hypochlorite, MTAD, and 2% chlorhexidine in the rapid disinfection of Resilon pellets. Resilon pellets were randomly selected, contaminated with Enterococcus faecalis, and disinfected with 5.25% sodium hypochlorite, MTAD, or 2% chlorhexidine. Positive and negative controls were used. All samples were air dried, washed in sterile water, placed in centrifuge tubes containing BHI broth, and incubated at 37 degrees C for up to 7 days. Broths were visually checked for turbidity and scored for growth. Samples from each experimental and control group were randomly chosen, plated, incubated at 37 degrees C, and checked visually for growth. If growth occurred, a gram stain was performed to identify bacterial species. Results indicate that 5.25% sodium hypochlorite, MTAD, and 2% chlorhexidine were all effective in the rapid disinfection of Resilon and gutta-percha pellets, and a 1-minute immersion was sufficient to disinfect.

Chlorhexidine↗

PubMed2004

Effect of chemical disinfectants on the transverse strength of heat-polymerized acrylic resins submitted to mechanical and chemical polishing.

STATEMENT OF PROBLEM: Immersion in chemical solutions used for cleansing and disinfecting prostheses can decrease the strength of denture base resins, making them more prone to fracture during use. PURPOSE: The purpose of this study was to assess the effect of immersion in different chemical disinfectants for varying time periods on the transverse strength of 3 mechanically or chemically polished heat-polymerized acrylic resins. MATERIAL AND METHODS: A total of 630 rectangular specimens (65 x 10 x 3 mm), 210 per resin (Classico, Lucitone 550, and QC-20), were fabricated. One side of each specimen was not polished and the other was either mechanically (n=300) or chemically (n=300) polished, and immersed for 10, 20, 30, 45, or 60 minutes in either 1%, 2.5%, or 5.25% sodium hypochlorite or 2% glutaraldehyde. Mechanically polished (n=15) and chemically polished (n=15) control specimens were immersed only in distilled water. The transverse strength (N/mm 2 ) was tested for failure in a universal testing machine, at a crosshead speed of 5 mm/min. Data were statistically analyzed using 2-way ANOVA and Student t test. Multiple comparisons were performed using Tukey and Scheffe tests (alpha=.05). RESULTS: There was significant difference (P < .01) between types of polishing, with chemical polishing resulting in lower transverse strength. ANOVA identified significant differences (P < .01) in strength between mechanically polished Lucitone 550 and QC-20, and among all 3 chemically polished resins. No significant differences were observed between resins submitted to both types of polishing or between different immersion periods (10 to 60 minutes), disinfectants, or interaction. CONCLUSIONS: Lucitone 550 resin presented the greatest transverse strength values with both types of polishing. Among the mechanically and chemically polished specimens, transverse strength was not affected after immersion in the disinfectants for the immersion periods tested (10 to 60 minutes). Chemically polished control and experimental (immersed in all solutions) QC-20 specimens showed significant differences in transverse strength values.

Acrylic Resins↗

PubMed2005

Experimental microbial contamination and disinfection of dry (vapour) shipper dewars designed for short-term storage and transportation of cryopreserved germplasm and other biological specimens.

Cryopreservation, storage and transport of cryopreserved germplasm without the risk of disease transmission is of great concern to animal and human health authorities. Here we report on the efficacy of microbial decontamination of the liquid nitrogen (LN) dry (vapour) shippers used for short-term storage and transportation of germplasm and other biological specimens. Dry shippers containing either a hydrophobic or a non-hydrophobic LN absorbent were experimentally contaminated with high titers of cultures of Pseudomonas aeruginosa, Escherichia coli, Staphylococus aureus, bovine viral diarrhea virus (BVDV) and bovine herpesvirus-1 (BHV-1). Biocidals with broad spectrum antimicrobial activity and gas vapours of formalin and ethylene oxide were used for disinfection of the dewars. Among the biocidals used, treatment with sodium hypochlorite solution, the quaternary ammonium-based disinfectants and peracetic acid were the most effective and useful for dry shippers with a hydrophobic LN absorbent. None of the bacterial or viral microorganisms were detected in samples of semen and embryos stored in dry shippers following their disinfection with these biocides. An application of some other disinfectants, due to their foaming properties or to the permeability of the absorbent hydrophobic membrane (HM) was not effective or may have caused irreversible damage to the LN absorbent. Gas sterilization by ethylene oxide in contrast to formalin was fully effective for both types of dry shippers.

Animals↗

PubMedDate not supplied

A non-biological surrogate for sequential disinfection processes.

An evaluation of Fluorescent YG-microspheres (Polysciences Inc.) was performed to simulate Cryptosporidium parvum (C. parvum) oocysts inactivation in treatment systems that utilize multiple disinfectants. Experiments were conducted in batch reactors that included an ozone primary stage and a secondary free chlorine treatment stage. A flow cytometer was used to track changes in the fluorescence intensity distribution due to exposure to the chemical disinfectant. Microsphere 'survival ratios' (N/No) were calibrated by selecting an appropriate fluorescence intensity threshold to replicate the inactivation of different C. parvum oocysts strains. Results showed that fluorescent microspheres displayed synergistic effects in the presence of two sequential disinfectants. In addition, microsphere structural tests showed that the polystyrene surface was damaged due to exposure to ozone. This polystyrene damage enhanced the diffusion of the secondary disinfectant into the microsphere, where dye was degraded in the opened polymer layer. As a result, YG-fluorescent microspheres is a promising non-biological technique that is capable of producing similar synergistic behavior as with C. parvum oocysts exposed to ozone followed by chlorine.

Animals↗

PubMed2004

Enhanced disinfection efficiency of mechanically mixed oxidants with free chlorine.

To the best of our knowledge, this study is the first investigation to be performed into the potential benefits of mechanically mixed disinfectants in controlling bacterial inactivation. The purpose of this study was to evaluate the disinfection efficiency of mechanically mixed oxidants with identical oxidant concentrations, which were made by adding small amounts of subsidiary oxidants, namely ozone (O3), chlorine dioxide (ClO2), hydrogen peroxide (H2O2) and chlorite (ClO2(-)), to free available chlorine (Cl2), using Bacillus subtilis spores as the indicator microorganisms. The mechanically mixed oxidants containing Cl2/O3, Cl2/ClO2 and Cl2/ClO2(-) showed enhanced efficiencies (of up to 52%) in comparison with Cl2 alone, whereas no significant difference was observed between the mixed oxidant, Cl2/H2O2, and Cl2 alone. This enhanced disinfection efficiency can be explained by the synergistic effect of the mixed oxidant itself and the effect of intermediates such as ClO2(-)/ClO2, which are generated from the reaction between an excess of Cl2 and a small amount of O3/ClO2(-). Overall, this study suggests that mechanically mixed oxidants incorporating excess chlorine can constitute a new and moderately efficient method of disinfection.

Bacillus subtilis↗

PubMed1999

Inactivation of Cryptosporidium parvum oocyst infectivity by disinfection and sterilization processes.

BACKGROUND: Cryptosporidium parvum is a common cause of self-limited gastroenteritis in the normal host but may cause severe disease in immunocompromised persons. Person-to-person transmission has been well documented in households, child care centers, and hospitals. Because contaminated environmental surfaces and medical devices such as endoscopes may play a role in disease transmission, we studied the susceptibility of C parvum to chemical agents commonly used for disinfection and evaluated the efficacy of sterilization processes. METHODS: Seven disinfectants were studied at their use dilution using a suspension test. Antimicrobial activity was assessed with the use of a cell infectivity assay. RESULTS: All sterilization processes tested (steam, ethylene oxide, Sterrad 100) inactivated 3 logs or greater of C parvum. The only liquid disinfectant/sterilant able to inactivate greater than 3 logs of C parvum was 6% and 7.5% hydrogen peroxide. Agents that did not completely inactivate C parvum included hydrogen peroxide at lower concentrations or exposure times, peracetic acid, sodium hypochlorite, a phenolic, a quaternary ammonium compound, 2% glutaraldehyde, and ortho-phthalaldehyde. CONCLUSIONS: Most high-level disinfectants used on endoscopes have limited efficacy against C parvum. However, the infectivity of C parvum on dry surfaces decreases rapidly. Therefore, current cleaning and high-level disinfection guidelines are adequate to prevent nosocomial transmission of C parvum by means of endoscopes.

Animals↗

PubMed1999

Disinfection of denture base acrylic resin.

STATEMENT OF PROBLEM: During repair or adjustments of acrylic resin removable complete and partial dentures, particles of the acrylic resin from the interior of the prosthesis may expose dental personnel to microbial health hazards if the prosthesis has not been thoroughly disinfected. PURPOSE: This study investigates the efficacy of a commercially prepared microbial disinfectant (Alcide) on the external and internal surfaces of acrylic resins. MATERIAL AND METHODS: Four groups of acrylic resin were incubated in an experimental model to simulate the oral environment over time. Specimens were treated in 2 groups, disinfected and not disinfected, and then further grouped by breaking and not breaking. Analysis was performed with microbial colony counts, SEM, and statistical analyses. RESULTS: Viable microorganisms still remain on the internal and external surfaces of treated resins. CONCLUSION: Chlorine dioxide reduces, but does not eliminate, viable microorganisms on these dental prostheses.

Acrylic Resins↗

PubMed2004

Disinfection of wastewater with peracetic acid: a review.

Peracetic acid is a strong disinfectant with a wide spectrum of antimicrobial activity. Due to its bactericidal, virucidal, fungicidal, and sporicidal effectiveness as demonstrated in various industries, the use of peracetic acid as a disinfectant for wastewater effluents has been drawing more attention in recent years. The desirable attributes of peracetic acid for wastewater disinfection are the ease of implementing treatment (without the need for expensive capital investment), broad spectrum of activity even in the presence of heterogeneous organic matter, absence of persistent toxic or mutagenic residuals or by-products, no quenching requirement (i.e., no dechlorination), small dependence on pH, short contact time, and effectiveness for primary and secondary effluents. Major disadvantages associated with peracetic acid disinfection are the increases of organic content in the effluent due to acetic acid (AA) and thus in the potential microbial regrowth (acetic acid is already present in the mixture and is also formed after peracetic acid decomposition). Another drawback to the use of peracetic acid is its high cost, which is partly due to limited production capacity worldwide. However, if the demand for peracetic acid increases, especially from the wastewater industry, the future mass production capacity might also be increased, thus lowering the cost. In such a case, in addition to having environmental advantages, peracetic acid may also become cost-competitive with chlorine.

Costs and Cost Analysis↗

PubMed1998

Corneal epithelial alterations resulting from use of chlorine-disinfected contact tonometer after myopic photorefractive keratectomy.

OBJECTIVE: This study aimed to describe a previously unreported complication associated with the use of chlorine-disinfected applanation tonometer heads for intraocular pressure measurement after excimer laser photorefractive keratectomy. DESIGN: Two retrospective case reports. PARTICIPANTS: Two patients underwent, respectively, a 7-diopter and a 4-diopter myopic excimer laser correction in their first eye 2 weeks apart. Complete epithelial closure of the ablated area was observed by biomicroscopy in the first-week examination. INTERVENTION: Four weeks after photorefractive keratectomy, a complete ophthalmic examination was performed. Goldmann applanation tonometry was performed bilaterally after thoroughly rinsing and drying the tonometer biprism, which had been immersed regularly in a chlorine 5000-parts per million solution. MAIN OUTCOME MEASURES: Slit-lamp examination and corneal topographic surface regularity were measured. RESULTS: A few minutes after applanation tonometry, both patients reported ocular discomfort in the excimer laser-treated eyes, whereas the untreated fellow eyes were painless. Punctate corneal lesions and superficial epithelial cell clumping were present in the first patient's treated eye, predominantly in the inferior aspect of the applanated cornea. Visual inspection showed a normal tonometer tip. In the second patient's treated cornea, a focal epithelial defect was identified biomicroscopically, which corresponded to the steeper region within the ablation zone on the videokeratograph. In this case, crystal deposits were found on the tonometer tip. The epithelial alterations resolved without sequelae in both cases. CONCLUSIONS: Disinfecting solutions of chlorine can cause crystal deposit formation on the tonometer head. Applanation tonometry after repeated disinfection with chlorine solutions appears to have the potential for disrupting the epithelial layer of the healing cornea. Covered contact tonometry or noncontact tonometry should be evaluated as alternative methods to chemically disinfected contact tonometry for intraocular pressure measurement after excimer laser surgery, especially during the first postoperative month.

Adult↗

PubMed2000

The formation of disinfection by-products in water treated with chlorine dioxide.

In this study, chlorine dioxide (ClO(2)) was used as an alternative disinfection agent with humic acid as the organic precursor in a natural aquatic environment. The major topics in this investigation consisted of the disinfection efficiency of ClO(2), the formation of disinfection by-products (DBPs), and the operating conditions. The results indicated that the pH value (pH 5-9) did not affect the efficiency of disinfection while the concentration of organic precursors did. The primary DBPs formed were trihalomethanes (THMs) and haloacetic acids (HAAs). The distribution of the individual species was a function of the bromide content. The higher the ClO(2) dosage, the lower the amount of DBPs produced. The amount of DBPs increased with reaction time, with chlorite ions as the primary inorganic by-product.

Chlorine Compounds↗

PubMed1990

Experiments on antiviral activity of hand disinfectants. Some theoretical and practical considerations.

Various members of the picornavirus family, adenovirus 2, papovavirus SV40, as well as rotaviruses were tested for inactivation of infectivity by hand disinfectants formulated on the basis of ethanol. The inactivating effect of povidine-iodine (Betaisodona) on enteroviruses and rotaviruses was also investigated. The degree of inactivation by these disinfectants on the various non-enveloped viruses studied, however, was found unpredictable. In fact, striking differences with the very same disinfectant existed even for members of one virus family. Isopropanol was inactive against enteroviruses. These findings are discussed from a theoretical point of view and practical implications are considered. Disinfection of poliovirus 1-contaminated hands by 80% (v/v) ethanol proved not very effective, despite encouraging results obtained in the suspension test. The load of rotavirus-contaminated hands, however, was substantially reduced by treatment with Desderman. A practical regimen can be proposed.

Adenoviruses, Human↗

PubMed1986

Chemical disinfection of human rotaviruses: efficacy of commercially-available products in suspension tests.

Suspension tests were conducted on 69 commercial and 7 non-commercial disinfectant formulations to determine which classes of chemicals were most active against human rotavirus (HRV). Virus samples, in the presence of varying levels of organic matter, were exposed to the disinfectants for 1 min. The levels of remaining infectious virus were determined by plaque assay. Products were rated by their ability to reduce the levels of infectious virus by more than 3 log10 in the presence or absence of tryptose phosphate broth (peptides and inorganic salts) or fecal matter. Of the commercially-available products tested, only 25% were rated as highly and 7% as moderately effective. The remaining 68% were either effective only in the absence of any additional organic matter (48%) or were completely ineffective (20%). The majority (64%) of the moderately and highly effective products were further examined for their ability to inactivate greater than 6 log10 of infectious HRV in the presence of fecal matter or tryptose phosphate broth. With one exception, all these products were still effective. Products potentially suitable as topical antiseptics, hard surface disinfectants and instrument soaks were identified. The results emphasize the care that should be exercised in the selection of disinfectants for the control and prevention of rotaviral infections.

Alcohols↗

PubMed1984

Surgical scrub and skin disinfection.

The role of pre-operative disinfection of the surgeon's hands and the skin of the operative site in the prevention of wound infection remains uncertain. The normal resident skin flora, consisting mainly of coagulase-negative staphylococci and aerobic and anaerobic diphtheroids, is an uncommon cause of infection except in prosthetic operations. Staphylococcus aureus is rarely a resident on normal skin other than the perineum, and is mostly present on the hands as a transient acquired from the nose. Nevertheless, it seems rational to kill or remove all transients on the hands of the surgeon and reduce residents to low levels. Surgical skin disinfection is usually assessed by measuring the reduction in organisms on the hands immediately after disinfection, after repeated applications of the disinfectant and after wearing gloves for two to three hours. The hands are commonly sampled in a bowl or plastic bag containing Ringer's or a similar solution and relevant neutralizers, or by the use of glove washings. A standardized technique is necessary to provide a statistical comparison between agents. Antiseptic detergents, chlorhexidine or povidone iodine show immediate reductions in bacterial counts of 70% to 80%, increasing to 99% after repeated application. Hexachloraphene and triclosan detergents show a lower immediate reduction but a good residual effect. Seventy percent ethyl or 60% propyl alcohol, with or without an antiseptic, show an immediate reduction of over 95%, and in excess of 99% on repeated application. Residual levels of organisms tend to be lower after repeated alcohol treatment than following the use of antiseptic detergents.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriological Techniques↗

PubMed1995

Resistance of microorganisms to disinfection in dental and medical devices.

The U.S. Centers for Disease Control and Prevention (CDC) recommends that only heat sterilization be used for all reusable devices entering the oral cavity. However, chemical disinfection is still employed for reprocessing dental devices in many areas of the world. In an analysis of a Florida dental practice responsible for nosocomial human immunodeficiency virus (HIV) transmissions, the possible role of contaminated devices was deemed unlikely in part because they were subjected to high-level disinfection with 2% glutaraldehyde. Disease transmissions have, however, been documented for endoscopes used in diagnostic and surgical procedures even after this treatment. In some dental devices, lubricants mix with potentially infectious patient materials, and organic debris has been observed in endoscopes after cleaning. We have investigated whether lubricants can render high-level chemical disinfection procedures ineffective and have addressed the role that some common devices may play in disease transmission. We report here that HIV in whole-blood samples and Pseudomonas aeruginosa in blood and plasma survived high-level disinfection when entrapped in lubricants used in dental handpieces and endoscopes. We also found that lubricated dental devices used to clean and polish teeth (prophylaxis angles) have the potential to transfer sufficient amounts of blood to infect human lymphocyte cultures with HIV. These results emphasize the need to subject reusable dental devices to a heat-sterilization protocol that penetrates the lubricant.

Bacterial Infections↗

PubMed2002

Impact of donor arm skin disinfection on the bacterial contamination rate of platelet concentrates.

BACKGROUND AND OBJECTIVES: Despite improved methods for detecting bacterial contamination of blood products, bacterial sepsis remains a significant risk in blood transfusion. This study was undertaken to investigate whether adopting a different skin disinfection protocol could reduce the rate of bacterial contamination of platelet concentrates. MATERIALS AND METHODS: Two skin disinfection protocols were consecutively used in the routine blood collection setting during two 10-month periods: 0.5% cetrimide/0.05% chlorhexidine solution followed by 70% isopropyl alcohol (first 10-month time-period); and 10% povidone-iodine followed by 70% isopropyl alcohol (second 10-month time-period). The rates of bacterial contamination of platelet concentrates were monitored by using a surveillance programme described previously. RESULTS: The overall bacterial contamination rate in the first time-period was 0.072%. After introduction of the povidone-iodine and isopropyl alcohol protocol, the bacterial contamination rate decreased to 0.042% (relative risk reduction: -0.42; 95% confidence interval, -0.12 to -0.61, P= 0.009). There were no differences in the types of micro-organisms identified (P = 0.7). CONCLUSIONS: Skin disinfection by povidone-iodine and isopropyl alcohol is more effective than that by cetrimide/chorhexidine and isopropyl alcohol in reducing venepuncture-associated contamination of platelet concentrates by skin flora. Our data indicate that the disinfection protocol should be used on a routine basis and such implementation should translate into a significant improvement in blood safety to patients receiving platelet transfusion.

2-Propanol↗

PubMed2000

Identification of the bacteriologicalcontamination of a water treatment line used for haemodialysis and its disinfection.

Renal haemodialysis care units in hospitals use enormous amounts of potable water for the functioning of 'artificial kidneys'. In order to avoid complications with patients' blood this water has to be specially treated. However, the treatment line itself can induce problems due to a high concentration of bacteria in the water. A high bacterial load, as well as bacterial toxins, can provoke immunological reactions in the patients. This paper shows that a granular activated carbon (GAC) filter is a source of bacterial contamination of the water due to the presence of a biofilm on the medium's surface. The majority of the bacteria released are Gram-negative. Because sloughing events in the biofilm can lead to dangerously high concentrations of bacteria and endotoxin levels in water, it is important to control this phenomenon. In treatment lines, GAC filters are regularly chlorinated. Our pilot experiment studied the disinfection of the filter with sodium hypochlorite and peracetic acid. Our results show that both disinfectants have a weak and transient effect on the biomass in the filter. It appears that chemical treatment of the filter is not the ideal solution to the bacteriological threat. Moreover, disinfection of the GAC filter transiently increases the contamination of the water. Alternative solutions to the use of chemical disinfection procedures are discussed.

Biofilms↗

PubMed1978

Bacteriological efficiency of a standardized cleansing and disinfection technique for duodenoscopes.

Adequate cleansing and disinfection of the endoscopes is desirable to prevent bacteriaemia and septicemia following gastrointestinal endoscopy, especially endoscopic retrograde cholangiopancreatography and duodenoscopic sphincterotomy. A practical method, proved in our department over a period of 12 months, is described. As the result of this standardized cleansing and disinfection technique using the aldehyde derivative Gigasept (succine dialdehyde and 2,5-dimethoxytetrahydrofuran) in a 10% concentration as chemical disinfectant, sterile cultures from the biopsy channel were obtained in 75% of tested instruments. The remaining fiberscopes exhibited only a few bacteria left, resulting in a sufficient success of disinfection according to hygienic standards.

Aldehydes↗