Tetrasodium Ethylenediaminetetraacetic Acid Research Articles

Association between 4%-tetrasodium EDTA and sepsis in neonatal piglets: A retrospective cohort study.

Central line-associated bloodstream infections are a major concern for children with intestinal failure and in animal research using parenteral nutrition (PN). In neonatal piglets receiving PN, we compared sepsis, line occlusions, line replacements, mortality, and costs with and without the use of a 4%-tetrasodium ethylenediaminetetraacetic acid (T-EDTA) locking solution. We performed a retrospective review of piglets with a central venous jugular catheter enrolled in 14-day exclusive PN (TPN) trials or in 7-day short bowel syndrome (SBS) trials, before and after initiation of T-EDTA. Lines were locked with a 1-ml solution for 2 h daily (T-EDTATPN, n = 17; T-EDTASBS, n = 48) and compared with our prior standard of care using 1.5-ml heparin flushes twice daily (CONTPN, n = 34; CONSBS, n = 48). Line patency and signs of sepsis were checked twice daily. Jugular catheters were replaced for occlusions whenever possible. Humane end points were used for sepsis not responding to antibiotic treatment or unresolved catheter occlusions. Compared with CON, sepsis was reduced using T-EDTA, significantly for TPN (P = 0.006) and with a trend for SBS piglets (P = 0.059). Line occlusions necessitating line changes were reduced 15% in TPN studies (P = 0.16), and no line occlusions occurred for T-EDTA SBS piglets. In our neonatal piglet research, use of T-EDTA locking solution decreased sepsis and, although not statistically significant, reduced occlusions requiring line replacements. Given the expense of animal research, adding a locking solution must be cost-effective, and we were able to show that T-EDTA significantly reduced total research costs and improved animal welfare.

Cost-utility analysis of 4% tetrasodium ethylenediaminetetraacetic acid, taurolidine, and heparin lock to prevent central line-associated bloodstream infections in children with intestinal failure.

Central line-associated bloodstream infections (CLABSI) are a serious complication in children with intestinal failure. This study assessed the incremental costs of 4% tetrasodium ethylenediaminetetraacetic acid (EDTA) compared with taurolidine lock and heparin lock per quality-adjusted life-year (QALY) gained in children with intestinal failure from the healthcare payer and societal perspective. A Markov cohort model of a 1-year-old child with intestinal failure was simulated until the age of 17 years (time horizon), with a cycle length of 1 month. The health outcome measure was QALYs, with results expressed in terms of incremental costs and QALYs. Model parameters were obtained from published literature and institutional data. Deterministic, probabilistic, and scenario sensitivity analyses were performed. 4% Tetrasodium EDTA was dominant (more effective and less expensive) compared with taurolidine and heparin, yielding an additional 0.17 QALYs with savings of CAD$88,277 compared with heparin, and an additional 0.06 QALYs with savings of CAD$52,120 compared with taurolidine lock from the healthcare payer perspective. From the societal perspective, 4% tetrasodium EDTA resulted in savings of CAD$90,696 compared with heparin and savings of CAD$36,973 compared with taurolidine lock. This model-based analysis indicates that 4% tetrasodium EDTA can be considered the optimal strategy compared with taurolidine and heparin in terms of cost-effectiveness. The decision uncertainty can be reduced by conducting further research on the model input parameters. An expected value of perfect information analysis can identify what model input parameters would be most valuable to focus on.

Tetrasodium EDTA for the prevention of urinary catheter infections and blockages.

Long-term catheterised individuals are at significant risk of developing catheter-associated urinary tract infections (CAUTIs), with up to 50% of patients experiencing recurrent episodes of catheter encrustation and blockage. Catheter blockage is a result of accumulation of carbonate apatite and struvite formed upon precipitation of ions within urine due to an infection-induced rise in pH. The aim of this study was to investigate the antimicrobial and anti-encrustation activities of tetrasodium ethylenediaminetetraacetic acid (tEDTA) to evaluate its potential efficacy in preventing CAUTIs and catheter blockages. The antimicrobial activity of tEDTA against uropathogens was assessed using time kill assays performed in artificial urine (AU). Crystallisation studies and in vitro bladder model assays were conducted to investigate the effect of tEDTA on struvite crystallisation and catheter blockage. tEDTA displayed bacteriostatic activity against Proteus mirabilis and prevented precipitation of ions in the AU. Crystallisation studies confirmed tEDTA inhibits struvite nucleation and growth via Mg2+ chelation with 7.63 mM tEDTA, equimolar to the concentration of divalent cations in AU, preventing the formation of crystalline deposits and blockage of Foley catheters for ≥168 h. The promising chelating abilities of low tEDTA concentrations could be exploited to inhibit encrustation and blockage of indwelling catheters. The fundamental research presented will inform our future development of an effective tEDTA-eluting catheter coating aimed at preventing catheter encrustation.

Control of Line Complications with KiteLock (CLiCK) in the critical care unit: study protocol for a multi-center, cluster-randomized, double-blinded, crossover trial investigating the effect of a novel locking fluid on central line complications in the critical care population

BackgroundInsertion of a central venous access device (CVAD) allows clinicians to easily access the circulation of a patient to administer life-saving interventions. Due to their invasive nature, CVADs are prone to complications such as bacterial biofilm production and colonization, catheter-related bloodstream infection, occlusion, and catheter-related venous thrombosis. A CVAD is among the most common interventions for patients in the intensive care unit (ICU), exposing this vulnerable population to the risk of nosocomial infection and catheter occlusion. The current standard of care involves the use of normal saline as a catheter locking solution for central venous catheters (CVCs) and peripherally inserted central catheter (PICC) lines, and a citrate lock for hemodialysis catheters. Saline offers little prophylactic measures against catheter complications. Four percent of tetrasodium ethylenediaminetetraacetic acid (EDTA) fluid (marketed as KiteLock Sterile Locking Solution™) is non-antibiotic, possesses antimicrobial, anti-biofilm, and anti-coagulant properties, and is approved by Health Canada as a catheter locking solution. As such, it may be a superior CVAD locking solution than the present standard of care lock in the ICU patient population.MethodsOur team proposes to fill this knowledge gap by performing a multi-center, cluster-randomized, crossover trial evaluating the impact of 4% tetrasodium EDTA on a primary composite outcome of the incidence rate of central line-associated bloodstream infection (CLABSI), catheter occlusion leading to removal, and use of alteplase to resolve catheter occlusion compared to the standard of care. The study will be performed at five critical care units.DiscussionIf successful, the results of this study can serve as evidence for a shift of standard of care practices to include EDTA locking fluid in routine CVAD locking procedures. Completion of this study has the potential to improve CVAD standard of care to become safer for patients, as well as provides an opportunity to decrease strain on healthcare budgets related to treating preventable CVAD complications. Success and subsequent implementation of this intervention in the ICU may also be extrapolated to other patient populations with heavy CVAD use including hemodialysis, oncology, parenteral nutrition, and pediatric patient populations. On a global scale, eradicating biofilm produced by antibiotic-resistant bacteria may serve to lessen the threat of “superbugs” and contribute to international initiatives supporting the termination of antibiotic overuse.Trial registrationClinicalTrials.gov NCT04548713, registered on September 9th, 2020.

Synthesis, Characterization and Release Studies of Ethylene Diamine Tetraacetic Acid (EDTA)-Antimicrobial Drug Conjugates for Colon Release

Background: The colon targeted drug delivery system is mainly useful for the topical treatment of colon diseases such as ulcerative colitis, Crohn’s disease OR colorectal cancers where we attain high local concentration and minimum side effects. In the present study we have synthesized some colon targeted Ethylene diamine tetra acetic acid (EDTA)-antimicrobial drug conjugates. Objectives: The goal of synthesizing EDTA-antimicrobial drug conjugates are that they reach intact in the colon and not be absorbed in the upper GIT, this is because of high molecular weight (>500) of the conjugates (Lipinski’s rule of 5). Materials and Methods: A series of EDTA-antimicrobial drug conjugates (E1-E5) were synthesized by stirring tetra sodium EDTA with antimicrobial drugs viz. Metronidazole (MTZ), Ornidazole (OZ), Ciprofloxacin (CF), Norfloxacin (NF) and Sulfamethoxazole (SM) in presence of EDAC ((1-ethyl-3(3-dimethylaminopropyl) carbodiimide). All the synthesized conjugates were characterized by FTIR, NMR (1H and 13C), Mass spectrometry and elemental analysis to identify structural components. The synthesized conjugates were screened for antimicrobial (antibacterial) and colon release studies. Results and Discussion: On the basis of chemical and spectral analysis EDTA-antimicrobial drug conjugates were synthesized and synthesized conjugates showed good antimicrobial (antibacterial) activity against tested stains. In-vitro release studies of the synthesized conjugates of the series have shown good release results which indicates that synthesized conjugates release the parent drug (antimicrobial drugs) to the colon. Conclusion: Synthesized conjugates improve drug delivery to the intestinal region. Release studies result suggest that the drugs begin to release from the conjugates in the distal intestinal region and appreciable release in the colon has been observed.

Chitosan hydrogel loaded with Aloe vera gel and tetrasodium ethylenediaminetetraacetic acid (EDTA) as the wound healing material: in vitro and in vivo study

AbstractThe main aim of the current study was to develop a chitosan hydrogel containing Aloe vera gel and Ethylenediaminetetraacetic acid (EDTA) as the wound healing materials. Chitosan with the concentration of (2% w/v) was prepared in AA (0.5%, v/v) and Tetrasodium EDTA (0.01% w/w) and AV (0.5% v/v) were added to the prepared polymer solution. As prepared solution was cross‐linked by β‐GP with the weight ratio of 1/6 w/w (1 chitosan and 6 β‐GP). The characterization of the hydrogels showed that the hydrogels have porous structures and interconnected pores with the pores size range from 41.5 ± 14 to 48.3 ± 11 μm. The swelling and weight loss measurements of the hydrogels showed that the hydrogels could swell up to 240% of their initial weight during 8 h and loss 79.7 ± 3.5% of the initial weight during 14 days. The antibacterial studies depicted that the prepared Cs/tEDTA/AV hydrogel inhibited the growth of Staphylococcus aureus (the minimum inhibition concentration, MIC of 73 ± 4.8) and Pseudomonas aeruginosa (the MIC of 40 ± 7.9). Moreover, the prepared hydrogels were hemocompatible (Cs/tEDTA/AV: OD of 0.24 ± 0.30) and biocompatible (Cs/tEDTA/AV: OD of 0.38 ± 0.01). At the final stage, the wound healing assessments in the animal model revealed that the application of the prepared hydrogels effectively enhanced the wound healing process. In conclusion, the results confirmed the efficacy of the prepared hydrogels as the wound healing materials.

Reduction of Central Line-Associated Bloodstream Infections and Line Occlusions in Pediatric Intestinal Failure Patients Receiving Long-Term Parenteral Nutrition Using an Alternative Locking Solution, 4% Tetrasodium Ethylenediaminetetraacetic Acid.

Patients with intestinal failure (IF) are dependent on parenteral nutrition (PN), however, they are at risk of central line-associated bloodstream infections (CLABSIs) and line complications. Four-percent tetrasodium ethylenediaminetetraacetic acid (EDTA) solution is an effective nonantibiotic, antimicrobial, antibiofilm, and anticoagulant agent. Our objective was to determine 4% tetrasodium EDTA efficacy in preventing CLABSIs and reducing line occlusions in pediatric IF patients. We conducted a retrospective cohort study of patients managed at 2 tertiary Canadian pediatric centers between April 2016 and December 2018 who received 4% tetrasodium EDTA solution under the brand name Kitelock. Data were collected for 12 months pre and post-Kitelock. CLABSIs and alteplase administration were compared using a Wilcoxon matched-pairs signed-rank test. Data were reported as medians and frequencies. Twenty patients were included (10 boys; median age, 83 months [range, 8-232 months]). The rate of CLABSIs before 4% tetrasodium EDTA was 2.7+4 per 1000 catheter days. Patients received 4% tetrasodium EDTA for a median of 365 (278-365) days, with no infections in the 12 months post-therapy (P = .002). Median rates of occlusive episodes for the entire cohort before 4% tetrasodium EDTA were 0 (0-5.0) and 0 (0-2.0) after starting therapy (P = .018). In patients with previous occlusions (n = 9), the median episodes of alteplase use previously was 5.5 (2.7-19.2) compared with 2.7 (0-2.7) (P = .018). Our preliminary findings suggest 4% tetrasodium EDTA solution is effective in reducing CLABSIs and catheter occlusions in pediatric patients with long-term central-access.

Efficacy of 4% tetrasodium ethylenediaminetetraacetic acid (T-EDTA) catheter lock solution in home parenteral nutrition patients: A quality improvement evaluation.

A functioning and reliable central venous access device is fundamental for home parenteral nutrition patients to administer essential nutrition. Complications of central venous access devices including occlusion, microbial colonization, and biofilm formation are problematic and sometimes life-threatening. A novel lock solution, 4% tetrasodium ethylenediaminetetraacetic acid, has properties that may reduce such complications. The aim of this study was to determine the safety, efficacy, and cost implications of implementing 4% tetrasodium ethylenediaminetetraacetic acid to prevent catheter-related complications in home parenteral nutrition patients. A pre- and post-intervention study was carried over 36 months (12 months pre; 24 months post) by the British Columbia Home Parenteral Nutrition Program in Vancouver, Canada, where 4% tetrasodium ethylenediaminetetraacetic acid was implemented for patients at high risk for central venous access device occlusion and catheter-related infection. Patients were included in the study if they had previous central venous access device complications. The outcomes evaluated were central line-associated bloodstream infection, catheter occlusion requiring thrombolytic treatment, and catheter replacements. In total, 22 out of 105 patients met the inclusion criteria. Two patients were excluded from analyses due to non-adherence and concomitant use of other lock solutions. Post intervention, 20 home parenteral nutrition patients experienced significant reduction in the central line-associated bloodstream infection rate (pre = 1.918/1000 catheter days; post = 0.563/1000 catheter days; p = 0.04) There were no occlusion events reported post intervention. For home parenteral nutrition patients, 4% tetrasodium ethylenediaminetetraacetic acid lock solution effectively reduces the risk of central venous access device complications including occlusions and catheter-related infections.

Cytotoxic effects of alkaline tetrasodium EDTA irrigating solutions.

The aim of this study is to determine the cytotoxic effects of tetrasodium ethylenediaminetetraacetic acid (EDTANa4) when used alone or when combined with sodium hypochlorite (NaOCl), with and without the addition of cetrimide (CTR). Human pulmonary fibroblast cell line was exposed to the following irrigating solutions: group 1, 2.5% NaOCl; group 2, 10% EDTANa4; group 3, 20% EDTANa4; group 4, 2.5% NaOCl/5% EDTANa4; group 5, 2.5% NaOCl/10% EDTANa4; group 6, 2.5% NaOCl/5% EDTANa4/0.2% CTR; group 7, 2.5% NaOCl/10% EDTANa4/0.2% CTR; group 8, control, cells in Dulbecco's modified Eagle's medium. Methyl thiazol tetrazolium assay was used to determine the viability of cells after 1 and 24 h. Viability percentages were analyzed for global comparison using the Welch test followed by the Games-Howell test to determine groups with similar viability, and the Student's t test was used to compare the two times. The lowest viability was obtained with a 2.5% NaOCl solution at both time periods. The association of NaOCl with EDTANa4 increased the cellular viability in direct relation with the concentration of the chelating agent. Globally, after 24 h of exposure, cell viability reduced. The solutions of EDTANa4 showed moderate cytotoxic effects when compared with NaOCl alone.

Therapeutic use of tetrasodium ethylenediaminetetraacetic acid solution for treatment of subcutaneous ureteral bypass device mineralization in cats.

BackgroundSubcutaneous ureteral bypass (SUB) device placement is an increasingly popular treatment option for decompression of ureteral obstruction in cats. Mineralization occlusion of the device occurs in a minority of cases but is the most common complication.ObjectiveTo evaluate a 2% tetrasodium ethylenediaminetetraacetic acid (tEDTA) solution for treatment of mineralization occlusion in cats with SUBs.AnimalsSix client‐owned cats (8 obstructed devices).MethodsCase series. Each cat was found to have device occlusion based on a combination of ultrasound examination, SUB irrigation, and failure to identify another cause of device obstruction. Each SUB was drained, irrigated using sterile saline, and infused with 1‐2 mL of 2% tEDTA solution. Success was defined as normalization of flow during subsequent ultrasound visualization while irrigating. The volume and frequency of tEDTA instillations, time to achieve device patency, follow‐up biochemical and ultrasound findings, and future reobstruction events were recorded.ResultsResolution of mineralization was documented in all 8 SUBs. Reobstruction events occurred in 2 cats, all of which resolved after additional tEDTA infusions, but 1 cat ultimately required device exchange at 356 days from the first tEDTA infusion. In 1 cat, a single infusion was prematurely discontinued because of persistent pelvic dilatation after 1.25 mL of tEDTA had been instilled. No complications were observed.Conclusions and Clinical ImportanceTetrasodium EDTA infusions can be safely considered as a treatment option for mineralized SUB devices in cats. This solution was easily infused, well tolerated, and avoided the need for SUB device exchange in the majority of cats in which it was used.

Dentine decalcification and smear layer removal by different ethylenediaminetetraacetic acid and 1-hydroxyethane-1,1-diphosphonic acid species.

To compare solutions of di- and tetrasodium ethylenediaminetetraacetic acid (EDTA) and 1-hydroxyethane-1,1-diphosphonic acid (HEDP) regarding their ability to solubilize calcium from dentine and remove smear layer. Solutions with a molarity corresponding to that of 17% Na2 EDTA (pH adjusted to 8.5) were prepared by dissolving Na2 and Na4 salts of HEDP (etidronate), or Na4 EDTA in deionized water. Standardized root dentine discs covered by a smear layer were prepared from human third molars. These discs (n=10 per group) were immersed in test solutions or phosphate-buffered saline for 1min. The dissolved Ca2+ was determined by atomic absorption spectroscopy, apparently opened dentinal tubules by laser scanning microscopy and automated image analysis. Ca2+ values were compared between groups by parametric, tubular areas by nonparametric methods, α=0.05. Solutions prepared from the tetrasodium salts were alkaline (pH 11.3-11.4), whilst counterparts made from the disodium salts were acidic. The EDTA solutions dissolved more calcium than the HEDP counterparts (P<0.05); solutions prepared with the disodium salts dissolved more calcium than those made from the tetrasodium salts (P<0.05). There was a high correlation between dissolved calcium and the apparently opened tubular areas (Spearman's ρ=0.81). Differences between groups regarding opened tubules were similar to those observed regarding the Ca2+ values, with a slightly reduced discerning power due to high variance. Calcium chelation and thus smear layer removal by EDTA and HEDP are influenced by pH.

Synthesis of Co3O4 nanoclusters via an EDTANa4-assisted route for enhanced electrochemical application

Three-dimensional (3D) Co3O4 nanoclusters were fabricated with the assistance of tetrasodium ethylene diamine tetraacetic acid (EDTANa4) through a one-pot wet-chemical reaction, featuring self-limiting assembly of building blocks and controlled regrowth process. The molar ratio of Co2+ and EDTANa4 plays a key role in building initial clusters as blocks, and the amount of NaOH effects the regrowth process. A possible formation mechanism for the Co3O4 nanoclusters was proposed based on the characterization results of X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The designed hierarchical Co3O4 nanoclusters exhibit a high specific capacitance of 221Fg−1 at a current density of 2Ag−1 in 2molL−1 KOH electrolyte.

Mixture of alkaline tetrasodium EDTA with sodium hypochlorite promotes invitro smear layer removal and organic matter dissolution during biomechanical preparation.

The aim of this study was to determine the following: (i) the quantity of free chlorine in mixtures of equal proportions of sodium hypochlorite (NaOCl) with trisodium ethylenediaminetetraacetic acid (EDTAHNa3 ) and alkaline tetrasodium ethylenediaminetetraacetic acid (EDTANa4 ); (ii) organic matter dissolution; and (iii) the time necessary to remove the smear layer by these irrigants alone and when mixed. The solutions were mixed in a 1:1 ratio and then iodometrically titrated over time to determine the quantity of free available chlorine. The capability of organic matter dissolution by the solutions alone and the mixtures of irrigants was analysed by weighing bovine muscle tissue specimens before andafter submission to the following groups (n=10): G1 - 0.9% saline solution (control), G2 - 2.5% NaOCl, G3 - 17% EDTAHNa3 , G4 - 10% EDTANa4 , G5 - 20% EDTANa4 , G6 - 5% NaOCl+17% EDTAHNa3 , G7 - 5% NaOCl+10% EDTANa4 and G8 - 5% NaOCl+ 20% EDTANa4 . The times necessary for smear layer removal were determinated on discs of bovine dentine with a standardized smear layer produced with SiC papers using a scanning electron microscope that did not require the samples to be sputter coated. The dentine discs were submitted to the same experimental groups previously described (n=10) over several time periods, and the photomicrographs acquired were scored for the presence of smear layer. The parametric data of tissue dissolution were analysed using two-way anova and one-way anova with Tukey's post hoc tests (α<0.05), whilst nonparametric data of smear layer removal were analysed by Friedman test (α<0.05) and the Kruskal-Wallis test with Dunn's post hoc (α<0.05). EDTAHNa3 caused an almost complete and immediate loss of free available chlorine from NaOCl, whilst EDTANa4 promoted a slow and concentrat-ion-dependent decline. The organic matter was not dissolved in the control group, EDTA groups or the mixture of NaOCl+17% EDTAHNa3 group (P>0.05). NaOCl alone and the associations of NaOCl + EDTANa4 dissolved tissue at all periods analysed (P<0.05). The smear layer was not removed in the control and NaOCl groups (P>0.05). The smearlayer was removed at 1min in the NaOCl+17% EDTAHNa3 group (P<0.05); 2min in 17% EDTAHNa3 group (P<0.05); and 5min in 10% EDTANa4 , 20% EDTANa4 , 5% NaOCl+10% EDTANa4 and 5% NaOCl+20% EDTANa4 groups (P<0.05). Alkaline EDTANa4 was slower in removing the smear layer than EDTAHNa3 , but when mixed with NaOCl during biomechanical canal preparation promoted organic matter dissolution and smear layer removal simultaneously. However, the mixing of NaOCl and EDTANa4 should be performed immediately before use to prevent the reduction of free available chlorine.

The corrosion process of P-110 steel in stimulation fluids used in the oil industry

The use of chelating agents in the oil well stimulation processes has been proposed as an alternative to the acid treatment when the formations damage do not allow the usage of strong chemical attack. However, this procedure can arouse the corrosion of the steel used in the infrastructure of the oil production. In this study, the corrosion kinetics of the P-110 steel in ethylenediaminetetraacetic acid (EDTA)-based fluids is assessed under different conditions of evaluation. Linear polarization was performed in different hydrodynamic regimes and at different temperatures, in order to evaluate the kinetic of steel corrosion. The working electrolyte solution comprises 10% disodium EDTA and 20% tetrasodium EDTA. The increase of temperature from 25 to 80°C in both electrolytes increments the corrosion rate of steel in at least one order of magnitude; particularly in EDTA-Na2 solutions. Corrosion rates of 0.29x101 and 1.67x102 mm.y-1 were measured at 25 and 80°C, respectively. The hydrodynamic regime plays an important role in the corrosion of steel only in the disodium solution, where corrosion rates were increased at higher rotation speeds of the electrode. The cathodic depolarization effect is more important in the EDTA-Na2 than in the EDTA-Na4 solution, making it more corrosive.

Occupational rhinitis and asthma due to EDTA‐containing detergents or disinfectants

Detergents and disinfectants are an emerging cause of work-related rhinitis and asthma. These products may contain ethylenediamine tetraacetic acid (EDTA). The authors report 10 cases of EDTA-related asthma and/or rhinitis. Review of the medical charts of patients who presented with work-related rhinitis (alone or with asthma), with a history of exposure to aerosols of EDTA-containing products and who underwent a nasal provocation test (NPT) with tetrasodium EDTA (1-4%) in our occupational health unit. Twenty-eight patients underwent a NPT with EDTA, which was positive in 10 cases. These patients, mostly cleaners or healthcare workers, used spray formulations of cleaning products. This case series is the first report of EDTA-related respiratory disease, documented by a specific test. An irritant mechanism is unlikely. Further studies are required to distinguish between an immunoallergic response and a pharmacological mechanism possibly resulting from calcium chelation, as suggested by animal experiments. A ban of spray preparations would be sufficient to prevent respiratory disease induced by EDTA inhalation, regardless of its mechanism.

Impact of Organic Acids/Chelating Agents on the Rheological Properties of an Amidoamine-Oxide Surfactant

Summary Surfactant-based acids have been used for diversion because they are less damaging to the formation. Amphoteric viscoelastic surfactant (VES) is the main type of surfactant being used today. Low viscosity is observed in the live-acid systems, whereas significantly increased viscosity is found when HCl reacts with carbonate and generates divalent salts. The surfactant/acid system can be broken after acid treatments by mixing with reservoir hydrocarbons, or by using an external or internal breaker. Amidoamine oxide, an amphoteric surfactant, was examined in this work. The prepared surfactant-based live-acid system contained 20 wt% HCl, 4 wt% surfactant, and 1 wt% corrosion inhibitor. Different organic acids/chelating agents were added to live and spent acids. Calcium carbonate particles were used to neutralize live acids. The objective was to examine how these organic acids/chelating agents affected the rheological properties of spent-acid systems. Measurements were made at temperatures from 75 to 200°F at a shear rate of 10 sec–1 and a pressure of 300 psi. Several simple organic acids (formic, acetic, propionic, and butyric) and chelating agents [glycolic acid, lactic acid, gluconic acid, citric acid, tetrasodium ethylenediamine tetraacetic acid (EDTA), tetrasodium L-glutamic acid, N, N-diacetic acid (GLDA), and disodium L-glutamic acid, N, N-diacetic acid (HEIDA)] that are used in the field were examined. Experimental results indicated that the addition of simple organic acids or chelating agents reduced the viscosity of spent acids significantly. This reduction in viscosity increased with the number of carbon atoms in the organic acid. The addition of organic acids reduced the temperature range in which the surfactant can be used. Chelating agents (α-hydroxy carboxylic acids and amino carboxylic acids) also tended to break the surfactant gel if enough chelant was used. On the basis of the results obtained, organic acids can be used to break surfactant gel. Transmission electron microscopy (TEM) tests were first conducted to examine how organic acids/chelating agents interfered with the formation of rod-like micelles in the surfactant-based acid. The results showed that the addition of organic acids to the spent acid generated a fewer elongated micelles and resulted in less apparent viscosity. In addition, if chelating agents or simple organic acids are used, then the concentration of the surfactant should be increased to compensate for the loss of viscosity induced by the addition of the organic acids.

The effect of EDTA instillations on the rate of development of encrustation and biofilms in Foley catheters

The aim of this research was to examine whether a daily instillation of tetra sodium ethylenediaminetetraacetic acid (EDTA) solution could reduce the rate at which encrustation by crystalline Proteus mirabilis biofilms blocks urinary catheters. Sets of three bladder models were fitted with size 14 all-silicone catheters. Tetra sodium EDTA solution was instilled into the catheter following biofilm development. Catheters were examined by digital photography and scanning electron microscopy for evidence of encrustation. The results showed that the mean time to blockage of the control catheters was 45 h for saline, 57 h for water and 67 h for those exposed to daily instillations of the EDTA solution. Statistical analysis confirmed that the mean encrustation rate on the EDTA-treated catheters was significantly lower than on the control-treated devices (P = 0.047). This in vitro study indicates that EDTA may have beneficial effects in reducing the complication of catheter encrustation and blockage by crystalline biofilms.

Bloodstream Infection: An Ounce of Prevention Is a Ton of Work

Bloodstream infection (BSI) remains the most important infectious complication of vascular access and is associated with prolonged hospital stay,1-4 increased costs,1,2,4 and, in some studies, attributable mortality.1-3,5 Prevention of BSI is essential, especially in patients requiring long-term vascular access for chemotherapy, parenteral nutrition, or hemodialysis. This issue of Infection Control and Hospital Epidemiology includes several articles about BSI: two evaluate novel anti-infective lock solutions for intravascular device–related BSI,6,7 one discusses barriers to the implementation of evidence-based recommendations for prevention of intravascular device–related BSI,8 one describes the outcomes of Staphylococcus aureus BSI in patients undergoing hemodialysis,9 and one evaluates excess mortality and costs associated with candidemia.10 Recent advances in our understanding of the pathogenesis of intravascular device–related BSI have led to the development of effective strategies for prevention.11-13 For long-term devices, it has been shown that the most common route of infection is intraluminal (ie, at the time of insertion or in the days following, microorganisms contaminate the hub [and lumen] of the intravascular device when the intravascular device is inserted over a percutaneous guidewire or later manipulated).14-16 A promising approach has involved instilling, or locking, an anti-infective solution into the device lumen to prevent colonization of the intraluminal surface by suspended planktonic-phase contaminants.17-19 In a meta-analysis of seven randomized, controlled trials, a vancomycin–heparin lock or flush solution was found to considerably reduce the risk of intravascular device–related BSI when compared with a heparin solution alone.20 There remains concern that a vancomycincontaining lock solution may promote the emergence of vancomycin-resistant organisms, although this is unlikely due to the infinitesimal quantities of vancomycin used. A surge in research exploring anti-infective lock solutions for the prevention and treatment of intravascular device–related BSI has led to the development of several new agents. Novel agents that have shown promise in case reports, pilot studies, or small clinical trials include, among others, taurolidine,21 gentamicin–citrate,22 minocycline–ethylenediaminetetraacetic acid (EDTA),23 and ethanol.24 In this issue of Infection Control and Hospital Epidemiology, Percival et al. report their findings regarding the efficacy of yet another novel lock solution, tetrasodium EDTA, for eradicating biofilms in an in vitro model system.6 They found that tetrasodium EDTA effectively eradicated (ie, no growth at the lower limit of detection) biofilms of S. epidermidis, Pseudomonas aeruginosa, Klebsiella pneumoniae, or Escherichia coli after 21 hours of lock treatment with 4 mL of a 40-mg/mL solution; eradication of biofilms of methicillin-resistant S. aureus or Candida albicans required a further 4 hours of treatment with a fresh lock solution. The study was limited by the fact that the biofilms studied were immature and lacked the complexity of in vivo biofilms and that there are no published data on the microbicidal activity of tetrasodium EDTA to make a strong case for its superiority over other lock solutions being studied. The same group of authors previously published a study of the efficacy of tetrasodium EDTA for eradication of biofilms developed in vivo and recovered from explanted catheters, which more closely approximates the clinical setting.25 Nonetheless, the results of the current study are intriguing

PNS‐CNS transitional zone of the first cranial nerve

This study examined the ultrastructure of the region of transition where fascicles of olfactory axons leave the peripheral nervous system (PNS) to enter the central nervous system (CNS), the so-called PNS-CNS transitional zone. Adult rats were transcardially perfused with a solution of 1% glutaraldehyde and 1% paraformaldehyde, decapitated, and the heads decalcified over a period of several weeks in a solution of 1% glutaraldehyde in 0.1 M tetrasodium ethylenediamine tetraacetic acid; the latter solution was changed daily. It was found that astrocytes did not form the glia limitans at the nerve entry zone, unlike the situation that exists in other cranial and spinal nerves. Rather, the glia limitans in this region of the olfactory bulb was formed by a special type of glial cell, referred to as an ensheathing cell. Ensheathing cells are found only in the nerve fiber layer of the olfactory bulb. They possess a mixture of Schwann cell and astrocytic features and are more likely to be of placodal than of CNS origin. The meningeal coverings of the olfactory nerve rootlets and of the olfactory bulb are also described and the functional implications of the findings discussed.

Intracellular proteases during sporulation and enterotoxin formation byClostridium perfringens type A

Intracellular proteolytic activity was detected in cell-free extracts ofClostridium perfringens NCTC 10239 and NCTC 8798. The kinetics of protease, enterotoxin, and spore formation as well as growth of the wild type at elevated temperature and the use of sporulation mutants indicated that most protease activity was related to sporulation. Intracellular protease activity was inhibited by a mixture of tetrasodium ethylenediaminetetraacetic acid and phenylmethylsulfonyl fluoride; this indicated the presence of an alkaline serine protease and a neutral metallo-protease. Stage 0 sporulation mutants produced only metallo-sensitive proteases; this indicated that only the serine protease was sporulation-specific.