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Decontamination of a Histoplasma capsulatum-infested bird roost in Illinois.

Histoplasma capsulatum was isolated from 27 of 34 soil specimens collected from a 3.23-hectare (8-acr) estate in illinois that had been the site of a bird roost for more than 10 yr. When the estate was sold to a developer for for the construction of a shopping center, it was feared that disturbing the roost would cause airborne transmission of spores of H. Capsulatum and thus create a public health hazard for the workmen and surrounding community. To prevent this, the bird roost was decontaminated with the application of 3,785 ml (1 gallon) of 3% formalin per square foot of soil. Safety precautions were taken to minimize the inhalation of dust and formalin by the decontamination team. Thirty-five soil specimens collected after application of the formalin were negative for H. capsulatum. No cases of histoplasmosis occurred among the decontamination workers, construction crews, or the general population. The total cost of the decontamination project was $75,000.

Animals↗

Decontamination of human skin exposed to 2,3,7,8-tetrachlorodibenzo-p-Dioxin (TCDD) in vitro.

Human post-mortem skin was exposed in vitro to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at 32 degrees C, under controlled humidity. In one-half of the samples, damage to the surface of the skin was simulated by stripping of the stratum corneum. After incubation with TCDD for 100 min, four different decontamination protocols were performed: (1) the sample was wiped with dry, adsorbent material (cotton balls); (2) a 10-min topical treatment with mineral oil was followed by dry wiping with cotton balls; (3) a 10-min topical treatment with mineral oil was followed by wiping with acetone-soaked cotton balls; and (4) the sample was washed with water and soap. After decontamination, skin samples were incubated (up to 300 min) again at 32 degrees C. One set of both intact and stripped TCDD-exposed skin samples was incubated for 300 min--absent decontamination--and was used as a control. Mineral oil treatment and acetone wipes, or water and soap, were effective in reducing (i.e., about two-fold) the amount of TCDD in the stratum corneum of intact skin. Mineral oil plus dry wipes reduced the amount of TCDD in the stratum corneum by about one-third, whereas dry wiping alone was ineffective. All protocols, however, were similarly effective in reducing the amount of TCDD in the epidermis and upper dermis; TCDD concentrations were decreased locally by factors of up to ten. In the lower dermis, a minimal effect of the decontamination procedures was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetone↗

Decontamination issues for chemical and biological warfare agents: how clean is clean enough?

The objective of this assessment is to determine what level of cleanup will be required to meet regulatory and stakeholder needs in the case of a chemical and/or biological incident at a civilian facility. A literature review for selected, potential chemical and biological warfare agents shows that dose information is often lacking or controversial. Environmental regulatory limits or other industrial health guidelines that could be used to help establish cleanup concentration levels for such agents are generally unavailable or not applicable for a public setting. Although dose information, cleanup criteria, and decontamination protocols all present challenges to effective planning, several decontamination approaches are available. Such approaches should be combined with risk-informed decision making to establish reasonable cleanup goals for protecting health, property, and resources. Key issues during a risk assessment are to determine exactly what constitutes a safety hazard and whether decontamination is necessary or not for a particular scenario. An important conclusion is that cleanup criteria are site dependent and stakeholder specific. The results of a modeling exercise for two outdoor scenarios are presented to reinforce this conclusion. Public perception of risk to health, public acceptance of recommendations based on scientific criteria, political support, time constraints, and economic concerns must all be addressed in the context of a specific scenario to yield effective and acceptable decontamination.

Biological Warfare↗

Water decontamination of chemical skin/eye splashes: a critical review.

Skin/eye chemical splashes are a significant workplace problem. Initial water decontamination is usually recommended, but there are few well-conducted experimental animal and human studies of efficacy. An extensive review of the literature and other available information sources was performed to define the scope of the problem and critically review the evidence for water decontamination efficacy. Although water decontamination can decrease the severity of chemical skin/eye burns, it cannot completely prevent them. An ideal replacement decontamination solution would be sterile, nontoxic, chelating, polyvalent, amphoteric, and slightly hypertonic to retard skin or corneal penetration of the chemical.

Animals↗

Selective decontamination of the digestive tract in neurosurgical intensive care unit patients: a double-blind, randomized, placebo-controlled study.

OBJECTIVES: The aim of this study was to assess, in a selected population, the effects of selective decontamination of the digestive tract on colonization of the oropharynx, trachea, stomach and rectum, and on the infection rate. An economical assessment was also performed. DESIGN: A prospective, double-blind, randomized, placebo-controlled, dual-center trial. SETTING: Two neurosurgical intensive care units. PATIENTS: A total of 191 comatose patients admitted emergently and intubated within < 24 hrs were enrolled. Of these patients, 68 were excluded because they either died, got an early infection, or were extubated within the first 5 days. A total of 123 patients were analyzed: 63 treated and 60 placebo patients. INTERVENTIONS: Topical antibiotics (tobramycin, polymyxin E, amphotericin B) were applied in the oropharynx and in the stomach. Vancomycin was added in the oropharyngeal paste. Placebo patients received the same regimen (i.e., a suspension of fluid and a paste) but without antibiotics. No parenteral antibiotics were given during the study period. MEASUREMENTS AND MAIN RESULTS: Bronchopneumonia episodes were diagnosed with protected specimen brush or plugged telescoping catheter and other infections were diagnosed according to the Center for Disease Control of Atlanta criteria. Antibiotic costs and cost per survivor were calculated. Selective decontamination of the digestive tract significantly reduced Gram-negative bacilli colonization as well as the number of episodes of bronchopneumonia, urinary tract infections, and sinusitis. Despite the addition of vancomycin, Staphylococcus aureus remained the main potential pathogen causing tracheal colonization and subsequent bronchopneumonia. The reduction in bronchopneumonia rate was observed in head-trauma patients only. We were able to show that: a) the trachea was the main reservoir of microorganisms responsible for pneumonia; b) pneumonia developed after tracheal colonization. Total charges for antibiotics were 2.8 times higher in the treated group than in the placebo group; in calculating the cost per survivor, selective decontamination of the digestive tract might be beneficial due to the reduced length of stay. CONCLUSIONS: Selective decontamination of the digestive tract is an effective technique in reducing infectious morbidity in comatose neurosurgical patients. Because of its cost, this technique should be used only in selected populations.

Adult↗

Radiation safety aspects of a hot-cell decontamination.

Extensive decontamination was conducted to prepare the interior of the argon cell at the Hot Fuel Examination Facility for refurbishment. The radiation field associated with 10-16 yr-old fission products was reduced by remote cleaning before personnel entry. This paper describes the operations, dosimetry, protective clothing, hardware and procedures used to ensure compliance with radiation exposure guidelines. Contact decontamination was conducted in general radiation levels that varied from 300 to less than 30 mrem/hr for that component of the radiation that could penetrate 540 mg per cm2 of aluminum. However, it was the nonpenetrating component that controlled in-cell stay times; it varied from 1500 to less than 130 mrem/hr. Even after decontamination, several areas of fixed contamination emitting over 1000 mrem/hr of nonpenetrating radiation were identified and locally shielded. There were 916 person-entries required for decontamination. These resulted in integrated exposures of 99 and 599 man-rem for the whole body and skin, respectively.

Decontamination↗

Selective bowel decontamination to decrease gram-negative aerobic bacterial and Candida colonization and prevent infection after orthotopic liver transplantation.

Gram-negative bacterial and fungal infections are a major cause of morbidity and mortality following liver transplantation. We therefore used selective bowel decontamination (SBD) to eliminate the endogenous source of gram-negative aerobic bacteria and Candida pathogens in an attempt to reduce the high incidence of infection related to these organisms. Thirty consecutive patients undergoing liver transplantation were treated with SBD starting 3 days prior to donor search and continuing for 21 days postliver transplantation. Selective bowel decontamination consisted of administering nonabsorbable antibiotics (Polymixin E, gentamicin, Nystatin) and a low bacterial diet. Surveillance cultures of the throat and rectum were obtained to monitor efficacy of selective bowel decontamination. In addition, in the posttransplant period, tracheal, wound, blood, and bile cultures were obtained to screen for gram-negative bacterial and Candida colonization and infection. Our baseline surveillance culture revealed that 29/30 (97%) of recipients were colonized with gram-negative aerobic bacteria and 16/30 (53%) with Candida. Three days after selective bowel decontamination was started, 26/30 (87%) were free of gram-negative bacteria, and 100% were free of Candida colonization of the gastrointestinal tract. There was a similar reduction in the oropharyngeal gram-negative aerobic bacteria and Candida colonization. In the first 30 days following liver transplantation, gram-negative infections were not diagnosed in any of our patients. Following discontinuation of SBD, recolonization of the gastrointestinal tract with gram-negative aerobic bacteria and Candida occurred within 5 days in 26/28 (90%) and 11/28 (35%), respectively. Our study suggests that prophylactive administration of nonabsorbable antibiotics will markedly reduce gram-negative aerobic bacterial and Candida colonization and appears to reduce the high incidence of infection related to these organisms in the early posttransplant period.

Adolescent↗

Quality improvement process in the adherence to gastric decontamination guidelines for poison exposures as recommended by a poison control center.

PURPOSE: Adherence to new guidelines for the use of ipecac syrup, gastric lavage, cathartics, and activated charcoal by a poison control center was studied with a quality improvement framework. METHODS: The rates of gastric decontamination were monitored through an electronic case record system. In February 2002, a revised guideline that narrowed the use of gastric decontamination was implemented with a performance improvement process. The rates of recommendation and utilization during 12 months following implementation of the new guidelines were compared with those during 12 previous months. RESULTS: Recommendations for the use of ipecac syrup declined from 1.50% to 0.02% (OR; 95% CI = 0.02; 0.01, 0.03), single-dose-activated charcoal declined from 5.39% to 1.38% (0.25; 0.22, 0.28), gastric lavage declined from 4.19% to 0.22% (0.05; 0.04, 0.06), and a cathartic declined from 1.48% to 0.13% (0.08; 0.06, 0.12). Declines in utilization were also significant (P < .001) for all forms of gastric decontamination. The proportions of patients managed at the scene of the poisoning were unchanged (1.04; 0.99, 1.09) before (67.64%) and after (68.50%) the new guidelines as were those for referral to a health care facility (20.57% and 21.42%, respectively, 1.05; 1.00, 1.11). CONCLUSION: Recommendations on gastric decontamination can be effectively modified with no detriment to patient outcome.

Decontamination↗

Decontamination of surgical instruments from prion proteins: in vitro studies on the detachment, destabilization and degradation of PrPSc bound to steel surfaces.

Effective reprocessing of surgical instruments ensuring elimination of inadvertent contamination with infectious agents causing transmissible spongiform encephalopathies (TSEs) is essential for the prevention of iatrogenic transmission of Creutzfeldt-Jakob disease (CJD) or its new variant (vCJD) from asymptomatic carriers. In a search for effective yet instrument-friendly and routinely applicable reprocessing procedures, we used an in vitro carrier assay to assess the decontamination activity exerted by different reagents on pathological prion protein (PrP(Sc)), the biochemical marker for TSE infectivity, attached to steel surfaces. In this assay, steel wires were contaminated with 263K scrapie brain homogenate and reprocessed for decontamination by exposure to several different test reagents. Residual contamination with PrP(Sc) and its protease-resistant core PrP27-30, still present after reprocessing on the wire surface or in the cleaning solution, was monitored by sensitive Western blot detection without or after proteinase K digestion. Using this approach, various reagents and processing conditions were screened for both their efficacy of decontamination and their active principles, such as detachment, destabilization or degradation of surface-bound prion protein. This revealed that, under appropriate conditions, relatively mild reagents such as 0.2 % SDS/0.3 % NaOH (pH 12.8), a commercially available alkaline cleaner (pH 11.9-12.2), a disinfectant containing 0.2 % peracetic acid and low concentrations of NaOH (pH 8.9) or 5 % SDS (pH 7.1) exert potent decontaminating activities on PrP(Sc)/PrP27-30 attached to steel surfaces. For in vivo validation, wires reprocessed in these reagents have been implanted into reporter animals in ongoing experiments.

Decontamination↗

Destruction of spores on building decontamination residue in a commercial autoclave.

The U.S. Environmental Protection Agency conducted an experiment to evaluate the effectiveness of a commercial autoclave for treating simulated building decontamination residue (BDR). The BDR was intended to simulate porous materials removed from a building deliberately contaminated with biological agents such as Bacillus anthracis (anthrax) in a terrorist attack. The purpose of the tests was to assess whether the standard operating procedure for a commercial autoclave provided sufficiently robust conditions to adequately destroy bacterial spores bound to the BDR. In this study we investigated the effects of several variables related to autoclaving BDR, including time, temperature, pressure, item type, moisture content, packing density, packing orientation, autoclave bag integrity, and autoclave process sequence. The test team created simulated BDR from wallboard, ceiling tiles, carpet, and upholstered furniture, and embedded in the BDR were Geobacillus stearothermophilus biological indicator (BI) strips containing 10(6) spores and thermocouples to obtain time and temperature profile data associated with each BI strip. The results indicated that a single standard autoclave cycle did not effectively decontaminate the BDR. Autoclave cycles consisting of 120 min at 31.5 lb/in2 and 275 degrees F and 75 min at 45 lb/in2 and 292 degrees F effectively decontaminated the BDR material. Two sequential standard autoclave cycles consisting of 40 min at 31.5 lb/in2 and 275 degrees F proved to be particularly effective, probably because the second cycle's evacuation step pulled the condensed water out of the pores of the materials, allowing better steam penetration. The results also indicated that the packing density and material type of the BDR in the autoclave could have a significant impact on the effectiveness of the decontamination process.

Bacillaceae↗

Ozone decontamination of bioclean rooms.

To establish a convenient method for decontaminating bioclean rooms, the effect of ozone at 80 mg/m3 for 72 h was compared with formaldehyde vaporization at an initial concentration of 150 mg/m3 with a gradual decrease to 20 mg/m3 during 72 h. Ozone was found to be inferior to formaldehyde in activity. When the bioclean room was decontaminated twice with ozone, the mean colony count per 10 cm2 was decreased to about the same level as when formaldehyde was used. Ozone had a strong caustic effect upon rubber materials. Despite these disadvantages, ozone decontamination was demonstrated to be superior to formaldehyde vaporization because of convenience, insignificant inhalation of the disinfectant by the hospital staff, and very rapid expulsion of the gas after ventilation. Because the disadvantages of ozone can be easily controlled, this study suggests that ozone decontamination is a promising method for maintaining bioclean rooms.

Bacillus subtilis↗

[Study on decontamination of radioactive ruthenium by steel wool in waste solution (author's transl)].

Tracer experiments were done in order to establish a decontamination process of 106Ru in radioactive waste solution by column method paying special attention on the solution of nitratonitrosyl complex of Ru which is often encountered as a low level radioactive waste solution. It turned out that metallic iron was the most effective decontaminating agent among the several tens of materials tested. The decontamination factor (DF) of 106Ru increased in proportion to the total surface area of iron and it sensitively depended on the oxidation state of the surface as revealed by the batchwise and columnwise tests. Iron samples with high corrosiveness gave a much larger DF than those with low corrosiveness. The decontamination process proceeded as iron was being oxidized via Fe(metal)leads toFe(II)leads toFe(III). As the results, the DF initially increased after initiating the passage of water through the column but it then decreased as the oxidation process became inactive. An excellent durability up to 10000 bed volumes was demonstrated by the column method at a high average DF of 150.

Alloys↗

Risk of endotoxemia during the initial phase of gut decontamination with antimicrobial agents.

Decontamination of the digestive tract with antimicrobial agents has been used for prevention and therapy of bacterial translocation. With regard to the well-described endotoxin-releasing properties of these agents, the question arises as to whether their enteral administration might result in an increased amount of intestinal endotoxins entering the circulation. Immunocompromised Wistar rats were intraduodenally challenged with live E. coli. Control animals received saline solution, decontaminated rats were treated with either tobramycin plus polymyxin B or ciprofloxacin alone through the duodenal tube. Plasma endotoxin activity and blood bacteria count were measured hourly over an observation period of 5 h. The intestinal bacterial count was determined at the end of the experiment. Gut decontamination in both groups receiving antimicrobial agents resulted in elevated plasma endotoxin levels compared with nondecontaminated controls. Maximum endotoxin levels were found to be 5-6 times higher in the ciprofloxacin group than in the control group and 2 times higher than in the tobramycin/polymyxin group. No positive blood cultures were detected. Intestinal bacterial count was similar in both treatment groups. Enterally applied antimicrobial agents bear an elevated risk of endotoxemia during the initial phase of gut decontamination. The amount of endotoxin translocating from the digestive tract to the circulation varies with the agents used. Polymyxin only partially reduced the observed endotoxin leakage from the gut.

Animals↗

Efficacy of hexafluorine for emergent decontamination of hydrofluoric acid eye and skin splashes.

Hexafluorine is an amphoteric, hypertonic, polyvalent compound for decontaminating hydrofluoric acid (HF) eye and skin splashes. In a German metallurgy facility during the period of 1994-1998, all eye or skin splashes with 40% HF alone or with a 6% HF/15% HNO3 mixture were initially decontaminated with Hexafluorine within 2 min following the splash at the accident site by the victims themselves or co-workers who witnessed the accident. Eleven workers using 40% HF or a 6% HF/15% HNO3 mixture sustained eye (2 cases) or skin (10 cases) splashes (1 combined) during 1994-1998. Hexafluorine was used within 2 min, and a second Hexafluorine decontamination was done on arrival at the plant infirmary. No further medical or surgical treatment was needed, no workers developed chemical burns, and none lost work time. These II cases demonstrate the efficacy of Hexafluorine in decontaminating HF or combined HF/HNO3 splashes.

Accidents, Occupational↗

Evaluation of CC2 as a decontaminant in various hydrophilic and lipophilic formulations against sulphur mustard.

OBJECTIVE: To evaluate CC2 (N, N'-dichloro-bis [2, 4, 6-trichlorophenyl] urea) in various hydrophilic and lipophilic formulations as a personnel decontaminant for sulphur mustard (SM). METHODS: Twenty percent of CC2 was prepared as a suspension or ointment with various chemical agents and its stability was evaluated by active chlorine assay. The efficacy was evaluated in mice by recording the mortality after applying 29 LD50 of SM (LD50 = 8.1 mg/kg dermally) and decontaminating it after 2 min with 200 mg of the formulation. Studies were also carried out with 10% and 20% CC2 in acacia and hydroxypropyl cellulose, and the suspensions were stored in polyethylene containers. The stability of the suspensions was evaluated by active chlorine assay. The efficacy was evaluated by recording the mortality after applying 29 LD50 of SM in mice and 12 LD50 of SM in rats (LD50 = 2.4 mg/kg dermally), and decontaminating it with the formulations. LD50 by different routes and primary skin irritation test of CC2 were also carried out. RESULTS: CC2 reacted with peanut oil and neem oil, and was unstable in povidone iodine and Fuller's earth. Good stability was achieved with petroleum jelly, honey, polyvinyl pyrrolidone, calamine lotion, acacia and hydroxypropyl cellulose. Though CC2 was stable in lipophilic formulations, it did not protect the animals. The hydrophilic formulations particularly acacia and hydroxypropyl cellulose gave very good protection and was stable in the polyethylene containers for a period of 1 year. The efficacy of 20% CC2 was better than 10% CC2. The oral and dermal LD50 of CC2 was found to be above 5.0 g/kg. CC2 was also found to be nonirritant. CONCLUSION: Twenty percent of CC2 in hydroxypropyl cellulose is better with respect to stability, efficacy and ease of decontamination. CC2 is also a safe chemical.

Administration, Cutaneous↗

[Decontamination of dental unit waterlines using disinfectants and filters].

Bacterial contamination of the dental unit water system can become a health problem for patients, particularly if they are immunodepressed. The present study has had the purpose of evaluating the effectiveness of methods of chemical decontamination using different disinfectants (peracetic acid, hydrogen peroxide, silver salts, chloramine T, glutaraldehyde T4) and methods of physical decontamination using synthetic membranes for the filtration of water. A preliminary removal procedure of the biofilm present in the waterline has been followed in a dental unit prepared on purpose for the research; subsequently different 2-week long maintenance procedures were applied using disinfectants injected by a pump and finally the bacterial contamination of the water flowing from the waterline was evaluated. The physical decontamination was performed using 0.22 mm membrane filters, which have been installed also in another dental unit, and the filtered water was analyzed to detect bacterial contamination. The preliminary procedure of biofilm removal succeeded obtaining germ-free water. Among the disinfectants used for the maintenance of the water quality only glutaraldehyde T4 was able to reduce the bacterial contamination under the limit suggested by the ADA. The membrane filter system was not able to purify the water, but when a disinfectant (peracetic acid) was used in the last part of the waterline good results were obtained. At present no decontamination system of dental waterline is available, and glutaraldehyde T4 seems to be the best disinfectant only if integrated with periodic biofilm removal for the maintenance of the water quality.

Biofilms↗

Pulse lavage washing in decontamination of allografts improves safety.

We analyzed the bacterial contamination rate of 140 femoral head allografts after rinsing the allografts in different decontamination solutions. Bacterial screening methods and cleansing effect of antibiotics (cefuroxime and rifampicin) and pulse lavage were compared. Swabbing and taking small pieces of bone for culture were the screening methods used. Both methods proved to be quite unreliable. Approximately one-fourth of the results were false negative. Culturing small pieces of bone gave the most accurate and reliable results and, therefore, can be recommended as a bacterial screening method. The use of antibiotics in allograft decontamination is controversial. In prophylactic use antibiotics include risks of allergic reactions and resistant development and our results in the present study show that antibiotics do not improve the decontamination any better than low-pressure pulse lavage with sterile saline solution. Therefore, pulse lavage with sterile saline solution can be recommended for allograft decontamination. Our results demonstrate that it decreases bacterial bioburden as effectively as the antibiotics without persisting the disadvantages.

Bacterial Infections↗

Optimisation of the time of milk sample decontamination with 0.75% cethylpirydinium chloride upon identification of Mycobacterium avium subsp. paratuberculosis.

Isolation of MAP from biological material, including milk, is very difficult. No matter how the fresh milk is obtained, it contains a certain number of rapidly growing microorganisms. Therefore, the decontamination process is applied in the methods of MAP isolation. Investigations were therefore undertaken to determine the optimal time of milk sample decontamination with 0.75% CPC. The experiment was divided into two parts: determination of the survival time of M.smegmatis and E. coli in 0.75% CPC and determination of the time of raw milk decontamination. The results suggest that the optimal time of milk sample decontamination is 15 min.

Animals↗