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PubMed2003

Decontamination of dental unit water systems with hydrogen peroxide.

AIMS: Transmission of microbial pathogens to patients from water in dental units is a concern. To reduce this risk, the decontaminating efficiency of hydrogen peroxide was evaluated. METHODS AND RESULTS: Three percent hydrogen peroxide diluted 1 : 4 in distilled water (contact time 15 min) was used daily to disinfect the waterlines of a pilot unit previously contaminated with Pseudomonas aeruginosa or Staphylococcus aureus. The behaviour of the test bacteria was seen to differ over time. Staph. aureus numbers slowly decreased until only low numbers were recovered, after which the levels remained stable. Ps. aeruginosa abatement was more rapid and the density of the bacteria reached a peak when the circuit was empty. CONCLUSIONS: Staph. aureus and Ps. aeruginosa treated with hydrogen peroxide fell from 6 to 4 log. SIGNIFICANCE AND IMPACT OF THE STUDY: Treatment of dental unit waterlines with hydrogen peroxide was seen to be able to keep the number of the bacteria under control, as long as the treatment was repeated daily.

Anti-Infective Agents, Local↗
PubMed1999

Antimicrobial prophylaxis in acute pancreatitis: selective decontamination versus antibiotics.

The results of several controlled clinical trials, published during the last 5 years, provide evidence of a beneficial role for early antimicrobial prophylaxis in severe acute pancreatitis. Pancreatic infections, especially gram-negative, which are of major importance with regard to morbidity and mortality, are gut-derived. Early enteral administration of antibiotics therefore seems the most logical measure to nip the danger in the bud. Intravenous antibiotics should adequately penetrate (peri)pancreatic tissues, i.e. necrotic tissues, and should be effective against the prevalent flora in infected necrotic tissues. However, the optimal route of administration is still a matter of debate. In contrast to one clinical trial using selective decontamination (SD) (i.e. enteral antibiotics combined with short systemic prophylaxis until SD is established), no clinical trial using intravenous antibiotics has been reported in which both pancreatic infections as well as mortality were reduced. Although the evidence supporting enteral administration, i.e. SD, is not unimpressive, further controlled clinical trials, in which the different ways of administration are compared, are warranted.

Acute Disease↗
PubMed2002

Endoscopic decontamination: an audit and practical review.

A comprehensive audit of endoscopic decontamination practices throughout a 1200-bedded teaching hospital trust was undertaken, prior to a review of the current policy and consideration of alternative disinfectants. Pharmacy records of glutaraldehyde usage, occupational health staff survey data of glutaraldehyde exposure, discussions with all departments where endoscopy might be conducted and information from all companies supplying endoscopes and allied equipment were reviewed. In total, 56 endoscopes were found to be in use in 16 areas of the Trust. In the main designated endoscopy units, compliance with the established policy was generally good, but in other areas, equipment which could tolerate autoclaving was being disinfected with chemical sterilants; some units were still using endoscopes which were not fully immersible and there was widespread use of disinfectant troughs, rather than automated washer-disinfectors. In most cases, this was because staff were concerned about endoscopy equipment passing to a central processing department with potential delays and losses. An updated Trust-wide endoscopy policy, using glutaraldehyde and incorporating the current British Thoracic Society, British Gastroenterological Society and British Urological Society guidelines, has now been implemented. The issues around this and alternative disinfectants are discussed.

Cross Infection↗
PubMed2003

Biofilm removal from silicone tubing: an assessment of the efficacy of dialysis machine decontamination procedures using an in vitro model.

The aim of this study was to assess the efficacy of 21 decontamination procedures, for the removal of a multispecies biofilm. Experiments were performed on five-day-old biofilms grown inside silicone tubing, using a reactor system that mimics a dialysis machine. The treatments were tested on 5 cm tubing samples. Effects of treatment were measured using direct microscopy following staining. Bacterial viability and endotoxin removal were determined using conventional microbiological methods following biofilm detachment by scraping. The 21 procedures were classified into four groups based on the amount of biofilm removed. The most effective treatment was an acid pre-treatment, followed by use of a concentrated bleach solution. Acid pre-treatment removes calcium and magnesium carbonate crystals that are always found in dialysis biofilms. Treatments performed at high temperature did not increase the efficacy of biofilm removal. Most treatments caused at least a 10(5)-fold reduction in bacterial viability with a few resulting in complete kill. Autoclaved and bleach-treated samples gave the best results for viability reduction, with both treatments providing an equally effective and complete kill. In addition, autoclaving led to a significant decrease in endotoxin level (removal of 99.99%).

Biofilms↗
PubMed1993

Decontamination of radioactive milk--a review.

The Chernobyl nuclear reactor accident in Russia in 1986 has further revealed the susceptibility of the environment to radioactive contamination. This can have serious implications for the safety of milk as well as other foods. Global fallout and other isotope releases can threaten to increase the radionuclide levels in milk alarmingly, and thus make it unfit for human consumption. Perception of such fears in the past resulted in considerable research efforts being directed towards radioactive decontamination of milk by different means. The holding of milk and milk products long enough to deactivate certain radioisotopes prior to consumption, conversion of milk into butter, and manufacturing cheese by using modified processes are some of the approaches in minimizing the radioactivity risk to consumers. Extensive studies carried out in the USA have shown that though somewhat expensive, ion-exchange treatment of milk in large-scale, automated plants can eliminate 90% or more of the radionuclides of concern, i.e. strontium-90, and iodine-131, and much of caesium-137. Various factors affecting the efficiency of the ion exchange process and properties of the treated milk are reviewed. Other processing techniques such as electrodialysis are also briefly discussed in relation to removal of radionuclides from milk.

Animals↗
PubMed2006

Particle generation by ultraviolet-laser ablation during surface decontamination.

A novel photonic decontamination method was developed for removal of pollutants from material surfaces. Such a method relies on the ability of a high-energy laser beam to ablate materials from a contaminated surface layer, thus producing airborne particles. In this paper, the authors presented the results obtained using a scanning mobility particle sizer (SMPS) system and an aerosol particle sizer (APS). Particles generated by laser ablation from the surfaces of cement, chromium-embedded cement, and alumina were experimentally investigated. Broad particle distributions from nanometer to micrometer in size were measured. For stainless steel, virtually no particle > 500 nm in aerodynamic size was detected. The generated particle number concentrations of all three of the materials were increased as the 266-nm laser fluence (millijoules per square centimeter) increased. Among the three materials tested, cement was found to be the most favorable for particle removal, alumina next, and stainless steel the least. Chromium (dropped in cement) showed almost no effects on particle production. For all of the materials tested except for stainless steel, bimodal size distributions were observed; a smaller mode peaked at approximately 50-70 nm was detected by SMPS and a larger mode (peaked at approximately 0.70-0.85 microm) by APS. Based on transmission electron microscopy observations, the authors concluded that particles in the range of 50-70 nm were aggregates of primary particles, and those of size larger than a few hundred nanometers were produced by different mechanisms, for example, massive object ejection from the material surfaces.

Aluminum Oxide↗
PubMed1990

Percutaneous absorption and skin decontamination of PCBs: in vitro studies with human skin and in vivo studies in the rhesus monkey.

Knowledge of the entry of polychlorinated biphenyls through the skin into the body and subsequent disposition aids estimation of potential for human health hazard. [14C]Aroclor 1242 and [14C]Aroclor 1254 were separately administered intravenously and topically to rhesus monkeys. Following iv administration, 30-d excretion was 39.4 +/- 5.9% urine and 16.1 +/- 0.8% feces (total 55.5 +/- 5.1%) for Aroclor 1242, and 7.0 +/- 2.2% urine and 19.7 +/- 5.8% feces (total 26.7 +/- 7.5%) for Aroclor 1254. Mineral oil and trichlorobenzene are common PCB cosolvents in transformers. Skin absorption of Aroclor 1242 was 20.4 +/- 8.5% formulated in mineral oil and 18.0 +/- 3.8% in trichlorobenzene (p greater than .05). Absorption of Aroclor 1254 was 20.8 +/- 8.3% in mineral oil and 14.6 +/- 3.6% in trichlorobenzene (p greater than .05). PCBs are thus absorbed through skin, and excretion from the body is slow. Vehicle (trichlorobenzene or mineral oil) did not affect percutaneous absorption. In vitro skin absorption in human cadaver skin did not correlate with in vivo findings. This was due to lack of PCB partition from skin into the water receptor fluid, even with addition of 6% Oleth 20 (Volpo 20) solubilizer. Skin decontamination of PCBs showed soap and water to be as effective as or better than the solvent ethanol, mineral oil, and trichlorobenzene in removing PCBs from skin. There is a dynamic time lapse for PCBs between initial skin contact and skin absorption (irreversible removal). Thus initially most PCBs could be removed from skin, but this ability decreased with time to the point where at 24 h only about 25% of the initial PCB skin dose could be recovered with skin washing.

Administration, Topical↗
PubMed1980

The decontamination of radium from a commercial building located in a large Canadian city.

In August, 1975, the Ministry of Health of the Province of Ontario at the request of one of the tenants of a building in a large Canadian city conducted a radiation survey of the third floor of the building. The survey, although preliminary, showed that high radiation existed on the third and second floors and that significant contamination existed in some other parts of the six-floor building. The contamination was identified as radium-226. An investigation revealed that the third floor of the building had been used during World War II for processing radium and also for some radium dial painting work. The Atomic Energy Control tboard (AECB) requested Atomic Energy of Canadian Limited (AECL) to remove the radium contaminant from the building. AECL assigned the job to its Chalk River Nuclear Laboratories (CRNL). The objectives were to reduce the radium concentration throughout the building so that radon decay products would be less than 0.02 Working Levels (WL) and exposure rates would be less than 50 microR/h. The techniques used and the extent of decontamination achieved are reported.

Accidents↗
PubMed1988

Biological safety cabinets, decontamination or sterilization with paraformaldehyde.

Bacillus subtilis var. niger spores were used to determine the exposure time for formaldehyde decontamination of biological safety cabinets. Formaldehyde contact times less than 3 hr were insufficient for sterilization. A contact time of 4 hr or more resulted in a reproducible killing of the spore strips placed inside the cabinets. At 6 hr sufficient formaldehyde had diffused through the high efficiency particulate air (HEPA) filter to sterilize the strips with lower spore counts. A minimum of 5 to 6 logs of killing were observed after 4 to 6 hr of treatment.

Bacillus subtilis↗
PubMed2004

Influence of selective bowel decontamination on the organisms recovered during bacteremia in neutropenic patients.

OBJECTIVE: To assess the influence of prophylactic selective bowel decontamination (SBD) on the spectrum of microbes causing bloodstream infection (BSI). DESIGN: The microbes causing BSI in neutropenic patients of a hematologic ward (HW) and a bone marrow transplantation unit (BMTU), respectively, were compared by retrospective analysis of blood culture results from January 1996 to June 2003. SETTING: A 30-bed HW (no SBD) and a BMTU including a 7-bed normal care ward and an 8-bed intensive care unit (SBD used) of a 2,200-bed university teaching hospital. RESULTS: The overall incidences of bacteremia in the HW and the BMTU were similar (72.6 vs 70.6 episodes per 1,000 admissions; P = .8). Two hundred twenty episodes of BSI were recorded in 164 neutropenic patients of the HW and 153 episodes in 127 neutropenic patients of the BMTU. Enterobacteriaceae (OR, 3.14; CI95, 1.67-5.97; P= .0002) and Streptococcus species (OR, 2.04; CI95, 1.14-3.70; P = .015) were observed more frequently in HW patients and coagulase-negative staphylococci more frequently in BMTU patients (OR, 0.15; CI95, 0.09-0.26; P < .00001). No statistically significant differences were found for gram-negative nonfermentative bacilli (P = .53), Staphylococcus aureus (P = .21), Enterococcus species (P = .48), anaerobic bacteria (P = .1), or fungi (P = .50). CONCLUSIONS: SBD did not lead to a significant reduction in the incidence of bacteremia, but significant changes in microbes recovered from blood cultures were observed. SBD should be considered when empiric antimicrobial therapy is prescribed for suspected BSI.

Adolescent↗
PubMed2006

The role of selective decontamination of the digestive tract in acute stroke.

BACKGROUND: following a stroke, morbidity and mortality is high, with aspiration pneumonia being a common complication. OBJECTIVES: to determine the levels of colonisation by and isolation of aerobic Gram-negative bacteria (AGNB) in acute stroke patients and determine the effect of selective decontamination of the digestive tract (SDD) on oral flora and whether it reduces both morbidity and mortality after an acute stroke. DESIGN: a prospective, randomised, placebo-controlled double blind trial. SETTING: acute stroke assessment units of three hospitals in the northwest of England. SUBJECTS: 203 patients admitted to hospital following a first acute stroke. METHODS: participants were randomised to SDD oral gel or placebo. Swallow was assessed on admission to hospital, and oral swabs were obtained thrice weekly. Demographic and clinical data were recorded. RESULTS: 203 patients (106 males and 97 females) participated, of whom 20 died during their hospitalisation, 19 withdrew and full follow-up was obtained for the remaining 164. A total of 122 AGNB were isolated in 105 samples from 48 patients. Abnormal swallow on admission was found in 58 patients (29%). A total of 34 patients carried a single gram-negative micro-organism that was present on one or more occasions. More than one AGNB was carried in 14 patients, and organisms were significantly more likely to be isolated from the placebo group than the active group during weeks 2 and 3 of treatment (P = 0.034, chi-squared). Seven patients in the placebo group and one in the treatment group developed pneumonia (P = 0.029, Fisher's exact test). CONCLUSIONS: high carriage of and colonisation by AGNB was found within this study, which was reduced by the addition of SDD. Although SDD reduced the presence of both organisms and documented episodes of pneumonia, mortality remained unchanged.

Acute Disease↗
PubMed1988

Decontamination of halothane from anaesthetic machines achieved by continuous flushing with oxygen.

The contamination of four types of anaesthetic machine with halothane was sequentially sampled by mass spectrometry while the machines were continuously flushed with oxygen 8 litre min-1 for up to 24 h. Contamination decreased in an exponential manner. Machines fitted with Selectatec vaporizer mounting systems and with the vaporizer removed showed contamination less than 0.02 parts per million (p.p.m.) of halothane after 12 h flushing. Machines with cage-mounted vaporizers or with vaporizers left connected to the Selectatec block demonstrated persisting contamination. The Fluotec Mk.4 vaporizer showed an improvement on earlier designs in this respect. Background contamination concentrations of greater than 0.05 p.p.m. were measured in a patient-free recovery area of an operating theatre suite. Concentrations increased to 1 p.p.m. when patients were admitted following halothane anaesthesia. Decontamination of anaesthetic machines to concentrations of halothane below those detected as background contamination within recovery areas may allow such machines to be used safely to anaesthetize patients at risk from halothane.

Anesthesia, Inhalation↗
PubMed1984

Biological inactivation by faeces of antimicrobial drugs applicable in selective decontamination of the digestive tract.

The in-vitro inactivation of seven antimicrobial drugs by human faecal substance has been investigated. Nalidixic acid, colistin, neomycin, tobramycin, temocillin, trimethoprim, and aztreonam were separately mixed in graded concentrations with faecal suspensions prepared from faeces of eight healthy volunteers. Each was mixed separately with a sample of each of the eight suspensions. All seven antimicrobial drugs appeared to be rapidly biologically inactivated by intestinal contents in a dose-dependent fashion, although not all to the same extent. The results may explain why with some unabsorbed or minimally absorbed drugs higher oral doses are required to achieve eradication of Gram-negative bacilli from the digestive tract than others, when selective decontamination (SD) is attempted in clinical practice.

Adult↗
PubMed2000

Selective digestive decontamination in patients in intensive care. The Dutch Working Group on Antibiotic Policy.

Selective digestive decontamination (SDD) is the most extensively studied method for the prevention of infection in patients in intensive care units (ICUs). Despite 27 prospective randomized studies and six meta-analyses, routine use of SDD is still controversial. In this review, we summarize the available scientific information on effectiveness of SDD in ICU patients. The effects of SDD have been studied in different combinations of the concept, using different antibiotics. Comparison of the individual studies, therefore, is difficult. In most studies, SDD resulted in significant reductions in the number of diagnoses of ventilator-associated pneumonia. However, incidences of ventilator-associated pneumonia in control groups ranged from 5% to 85%. Moreover, these reductions in incidences of ventilator-associated pneumonia in individual studies were not associated with improved patient survival, reductions of duration of ventilation or ICU stay, or reductions in antibiotic use. The numbers of patients studied are too small to determine effects on patient survival. Although two meta-analyses suggested a 20% mortality reduction when using the full concept of SDD (topical and systemic prophylaxis) these results should be interpreted with caution. Formal cost-benefit analyses of SDD have not been performed. SDD is associated with the selection of microorganisms that are intrinsically resistant to the antibiotics used. However, the studies are too small and too short to investigate whether SDD will lead to development of antibiotic resistance. As long as the benefits of SDD (better patient survival, reduction in antibiotic use or improved cost-effectiveness) have not been firmly established, the routine use of SDD for mechanically ventilated patients is not advised.

Antibiotic Prophylaxis↗
PubMed2000

In vitro susceptibility of Helicobacter pylori to, and in vivo suppression by, antimicrobials used in selective decontamination of the digestive tract.

The incidence of bleeding related to stress ulcers is reduced in critically ill patients in whom gut decontamination has been performed; this may be a result of suppression of Helicobacter pylori infection. We determined the susceptibility of H. pylori to the applied antibiotics. In nine of 10 critically ill patients (using intravenous cefotaxime and topical polymyxin, tobramycin and amphotericin B (PTA) given by nasogastric tube) and all six volunteers (using PTA alone), H. pylori was suppressed as long as the topical antibiotics were ingested. The in vitro studies revealed that all strains were susceptible to cefotaxime and tobramycin. The strains were not susceptible to polymyxin or amphotericin B.

Administration, Topical↗
PubMed2006

Emergence of multidrug-resistant Gram-negative bacteria during selective decontamination of the digestive tract on an intensive care unit.

OBJECTIVES: During treatment with selective decontamination of the digestive tract (SDD), four multidrug-resistant (MDR) strains, three different Escherichia coli and one Klebsiella pneumoniae, were isolated from four patients not known as carriers of such MDR strains before their admission to the intensive care unit (ICU) in the Academic Medical Center (AMC) in Amsterdam. These isolates were extended-spectrum beta-lactamase (ESBL)-positive. We investigated whether this was due to interspecies transfer of resistance genes. METHODS: The MDR strains were typed by amplified fragment length polymorphism (AFLP) analysis. The plasmids from these strains were characterized by restriction fragment length polymorphism and the resistance genes were characterized by PCR and sequence analysis. RESULTS: The strains were genetically unrelated and contained identical plasmids with ESBL genes. CONCLUSIONS: We identified an outbreak of plasmid-mediated ESBL genes during SDD treatment in the ICU. The use of third-generation cephalosporins in SDD is associated with the emergence of ESBLs. We conclude that identification of emerging MDR Gram-negative bacteria and recognition of resistance plasmid transfer during SDD treatment are crucial for optimal application of this regimen in ICUs.

Anti-Bacterial Agents↗
PubMedDate not supplied

Hair analysis for cocaine: the requirement for effective wash procedures and effects of drug concentration and hair porosity in contamination and decontamination.

It has been proposed that issues of external contamination of hair can be resolved by the presence of metabolites. This is true for some drugs in some circumstances. However, even if some metabolites such as cocaethylene are sufficiently definitive to indicate certainty of use, others such as benzoylecgonine can occur as contaminants. In addition, for phencyclidine, only the parent compound is determined. Therefore, effective washing procedures are needed to rule out contamination as the source of the parent or metabolite. The protection provided by cutoffs is also dependent on washing to remove surface contamination, which can range from very little to greater than 20 times the amount in the hair. In cocaine-positive head hair samples from 67 subjects with cocaine-positive urine tests, contamination of positive hair samples ranged from 0.7 to 8009 ng/10 mg hair, demonstrating that analyses of such samples to determine use is meaningless without removal of contamination. Wash procedures have been a focus of this laboratory for many years. In this paper, the effectiveness of our wash procedure was further challenged by application to negative hair (blonde, auburn, brown, and black) contaminated by soaking for 1 h in 1000, 10,000, and 50,000 ng cocaine/mL water. The uptake of the cocaine was approximately linear with increasing concentrations of cocaine in the soaking solutions. By application of the wash criterion, all samples were clearly identified as contaminated (i.e., negative). The effects of hair porosity on uptake of cocaine were also studied with 10 hair samples of all colors. Permed and unpermed samples were soaked in 10,000 ng cocaine/mL for 1 hour. All hair responded to the perm with increased uptake, and all were decontaminated or identified as contaminated (i.e., negative for cocaine use). Porosity, not hair color, determined the rate of penetration of hair by cocaine in solution, and, likewise, washing characteristics were unrelated to hair color.

Cocaine↗
PubMed2002

No effect of preoperative selective gut decontamination on endotoxemia and cytokine activation during cardiopulmonary bypass: a randomized, placebo-controlled study.

BACKGROUND: Cardiopulmonary bypass predisposes the splanchnic region to inadequate perfusion and increases in gut permeability. Related to these changes, circulating endotoxin has been shown to rise during cardiac surgery, and may contribute to cytokine activation, high oxygen consumption, and fever ("postperfusion syndrome"). To a large extent, free endotoxin in the gut is a product of the proliferation of aerobic gram-negative bacteria and may be reduced by nonabsorbable antibiotics. OBJECTIVE: To evaluate the effect of preoperative selective gut decontamination (SGD) on the incidence of endotoxemia and cytokine activation in patients undergoing open heart surgery. DESIGN: Prospective, randomized, placebo-controlled double-blind trial. SETTING: Tertiary-care university teaching hospital. INTERVENTION: Preoperative administration for 5 to 7 days of oral nonabsorbable antibiotics (polymyxin B and neomycin) vs. placebo. The efficacy of SGD was assessed by culture of rectal swabs. PATIENTS: Forty-four patients (median age 65 yrs, 29 males) were included in a pilot study to establish the sampling points of perioperative measurements. Seventy-eight consecutive patients (median age 65 yrs, 55 males) were enrolled for the prospective study; of these, 51 were randomly allocated to take SGD (n = 24) or placebo (n = 27); 27 were included in a control group (no medication). MEASUREMENTS AND RESULTS: SGD but not placebo effectively reduced the number of rectal swabs that grew aerobic gram-negative bacteria (27% vs. 93%, respectively; p < .001). SGD did not affect the occurrence of perioperative endotoxemia, nor did it reduce the tumor necrosis factor-alpha, interleukin-10, or interleukin-6 concentrations (p > .20), as determined before surgery, upon aorta declamping, 30 mins into reperfusion, or 2 hrs after surgery. Also, SGD did not alter the incidence of postoperative fever or clinical outcome measures such as duration of artificial ventilation and intensive care unit and hospital stay. CONCLUSION: SGD effectively reduces the aerobic gram-negative bowel flora in cardiac surgery patients but fails to affect the incidence of perioperative endotoxemia and cytokine activation during cardiopulmonary bypass and the occurrence of a postperfusion syndrome.

Aged↗