scholarly journals Comparison of Hydrogen Peroxide Contact Lens Disinfection Systems and Solutions against Acanthamoeba polyphaga

2001 ◽  
Vol 45 (7) ◽  
pp. 2038-2043 ◽  
Author(s):  
Reanne Hughes ◽  
Simon Kilvington
Keyword(s):  
Hydrogen Peroxide ◽  
Contact Lens ◽  
Lens Protein ◽  
Sodium Perborate ◽  
Acanthamoeba Polyphaga ◽  
Log Reduction ◽  
Disinfection Process ◽  
Free Living Amoeba ◽  
One Step ◽  
Corneal Damage

ABSTRACT Acanthamoeba is a free-living amoeba causing a potentially blinding infection of the cornea. Contact lens wearers are most at risk and account for some 95% of cases. Hydrogen peroxide is used for contact lens disinfection due to its broad antimicrobial activity. Lenses must be neutralized before use to avoid pronounced stinging and possible corneal damage. Neutralization is achieved by adding a catalyst during the disinfection process (one-step) or afterwards (two-step). Here, the activities of commercial peroxide systems and individual solutions against trophozoites and cysts ofAcanthamoeba polyphaga were compared. All disinfection systems were active against trophozoites, giving a ≥3-log (99.9%) kill within 1 h. Of the four one-step systems, only one showed some cysticidal activity, giving a 1.28 ± 0.41-log reduction. Both two-step systems were cysticidal, giving a ≥3-log kill at 4 h. All system peroxide solutions were cysticidal, giving a ≥3-log kill by 4 to 6 h. Variation in the cysticidal rate was observed with two solutions that gave a 1.8- to 2.1-log kill at 4 h compared with 3.0 to 4.0 for the rest (P < 0.05). No cysticidal activity was found with the peroxigen sodium perborate or the contact lens protein remover subtilisin A. Two-step systems are cysticidal providing contact times of at least 4 h are employed. Variation in cyst killing occurs between peroxide solutions, possibly due to formulation differences. One-step systems are less effective againstAcanthamoeba cysts due to rapid peroxide neutralization. The cysticidal activity of one-step systems could be improved if neutralization rates were retarded.

scholarly journals Evaluating Alternate Methods of Determining the Antimicrobial Efficacy of Contact Lens Care Products against Acanthamoeba Trophozoites

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 126 ◽  
Author(s):  
Allison Campolo ◽  
Paul Shannon ◽  
Monica Crary
Keyword(s):  
Propidium Iodide ◽  
Contact Lens ◽  
Acanthamoeba Keratitis ◽  
Antimicrobial Efficacy ◽  
Ocular Infection ◽  
Outer Membranes ◽  
Log Reduction ◽  
Free Living Amoeba ◽  
Corneal Damage ◽  
Rapid Tool

Acanthamoeba keratitis (AK) is a serious ocular infection caused by a ubiquitous free-living amoeba, Acanthamoeba. This infection often results in extensive corneal damage and blindness, and is notoriously difficult to cure. While Acanthamoeba is an abundant organism, AK is most associated with contact lens hygiene noncompliance and inadequate contact lens care (CLC) disinfection regimens. Thus, accurate and timely antimicrobial efficacy testing of CLC solutions is paramount. Published methods for antimicrobial efficacy testing of Acanthamoeba trophozoites requires 14 days for results. Presently, alternate and/or rapid methods for evaluating CLC products rarely demonstrate equivalent results compared to commonly-reported methods. Propidium iodide is a cellular stain that can only bind to cells with damaged outer membranes. We evaluated propidium iodide staining as an alternative method for determining the relative antimicrobial efficacy of 11 different CLC products against Acanthamoeba trophozoites. Following exposure to a CLC product, the fluorescence intensity of propidium iodide in an Acanthamoeba population demonstrated a strong correlation to the log reduction determined by established, growth-based Acanthamoeba testing used to evaluate the antimicrobial efficacy of CLC products. Thus, propidium iodide was found to be an effective rapid tool for determining cell death in Acanthamoeba trophozoites following exposure to CLC solutions.

scholarly journals Enhanced Killing of Acanthamoeba Cysts with a Plant Peroxidase-Hydrogen Peroxide-Halide Antimicrobial System

2003 ◽  
Vol 69 (5) ◽  
pp. 2563-2567 ◽  
Author(s):  
Reanne Hughes ◽  
Peter W. Andrew ◽  
Simon Kilvington
Keyword(s):  
Hydrogen Peroxide ◽  
Horseradish Peroxidase ◽  
Contact Lens ◽  
Acanthamoeba Keratitis ◽  
Free Living ◽  
Soybean Peroxidase ◽  
Plant Peroxidase ◽  
Time Points ◽  
Free Living Amoeba ◽  
Care Systems

ABSTRACT The activity of H2O2 against the resistant cyst stage of the pathogenic free-living amoeba Acanthamoeba was enhanced by the addition of KI and either horseradish peroxidase or soybean peroxidase or, to a lesser degree, lactoperoxidase. This resulted in an increase in the cysticidal activity of 3% (wt/vol) H2O2, and there was >3-log killing in 2 h, compared with the 6 h required for comparable results with the peroxide solution alone (P < 0.05). With 2% H2O2, enhancement was observed at all time points (P < 0.05), and total killing of the cyst inoculum occurred at 4 h, compared with 6 h for the peroxide alone. The activity of sublethal 1% H2O2 was enhanced to give 3-log killing after 8 h of exposure (P < 0.05). No enhancement was obtained when KCl or catalase was used as a substitute in the reaction mixtures. The H2O2 was not neutralized in the enhanced system during the experiments. However, in the presence of a platinum disk used to neutralize H2O2 in contact lens care systems, the enhanced 2% H2O2 system gave 2.8-log killing after 6 h or total cyst killing by 8 h, and total neutralization of the H2O2 occurred by 4 h. In contrast, 2% H2O2 alone resulted in <0.8-log killing of cysts in the presence of the platinum disk due to rapid (<1 h) neutralization of the peroxide. Our observations could result in significant improvement in the efficacy of H2O2 contact lens disinfection systems against Acanthamoeba cysts and prevention of acanthamoeba keratitis.

One-Step Oxidation of Benzene Producing Eight High Value Compounds Using Nitric Acid and Hydrogen Peroxide

2015 ◽  
Vol 19 (0) ◽  
pp. 55-58
Author(s):  
Zhen-xue Liu ◽  
◽  
Zhong-xue Gan ◽  
Jun-jie Gu ◽  
Qing-feng Song
Keyword(s):  
Hydrogen Peroxide ◽  
Nitric Acid ◽  
One Step ◽  
Oxidation Of Benzene

Fast one-step synthesis of N-doped carbon dots by pyrolyzing ethanolamine

2014 ◽  
Vol 2 (36) ◽  
pp. 7477-7481 ◽  
Author(s):  
Xinwei Dong ◽  
Yanjie Su ◽  
Huijuan Geng ◽  
Zhongli Li ◽  
Chao Yang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Carbon Dots ◽  
High Yield ◽  
One Step ◽  
Doped Carbon Dots

N-doped CDs can be obtained directly with high yield by pyrolyzing ethanolamine in air within just 7 minutes with the assistance of hydrogen peroxide.

The application of inexpensive and synthetic simple electrocatalyst CuFe-MoC@NG in immunosensor

The Analyst ◽  
2021 ◽  
Author(s):  
Lisha Mei ◽  
Wentang Zhao ◽  
Yiju Song ◽  
Li Zhang ◽  
Mengmeng Zhang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Precious Metal ◽  
Doped Graphene ◽  
One Step ◽  
Metal Materials ◽  
First Time

In this study, we used inexpensive and synthetic simple electrocatalysts replacement conventional precious metal materials to reduce hydrogen peroxide (H2O2). We first time developed N-doped graphene-coated CuFe@MoC using one-step calcination...

scholarly journals Aferição do pH de diferentes agentes clareadores indicados para o clareamento intracoronário

2018 ◽  
Author(s):  
João Felipe Besegato ◽  
Gabriela Dos Santos Ribeiro Rocha ◽  
Marlene De Sousa Amorim ◽  
Fabio Martins Salomão ◽  
Daniel Poletto ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Statistical Analysis ◽  
Multiple Comparisons ◽  
The Other ◽  
Sodium Perborate ◽  
Distilled Water ◽  
Friedman Test ◽  
Time Intervals ◽  
Ph Values ◽  
Evaluation Time

Objective: to measure pH values of bleaching agents that are indicated to intracoronal bleaching technique in different time intervals. Methods: Each group (G) received five samples (n=5): G1 – distilled water (AD); G2 – hydrogen peroxide (H2O2) 30%; G3 – sodium perborate (PbS) + AD; G4 – PbS + H2O2 30%; G5 – sodium percarbonate (PcS) + AD; and G6 – PcS + H2O2 30%. pH values were stated using a digital pHmeter, in different time intervals: immediately after handling (T0), 24 hours (T1) and 168 hours after handling (T2). The results were submitted to statistical analysis through Kruskal-Wallis and Mann Whitney tests, in this order, allowing multiple comparisons among the groups. To verify the effect of time in each group, Friedman test was applied. Results: In the evaluation of the effect of time in each group, it was observed that G2 presented acid behavior, while the other groups exhibited values close to neutrality or alkaline. Conclusions: H2O2 30% was the only agent that showed acidic behavior in every evaluation time. Meanwhile, PcS + H2O had the highest pH values.

Inactivation of Escherichia coli O157:H7, Salmonella enterica Serotype Enteritidis, and Listeria monocytogenes on Lettuce by Hydrogen Peroxide and Lactic Acid and by Hydrogen Peroxide with Mild Heat

2002 ◽  
Vol 65 (8) ◽  
pp. 1215-1220 ◽  
Author(s):  
CHIA-MIN LIN ◽  
SARAH S. MOON ◽  
MICHAEL P. DOYLE ◽  
KAY H. McWATTERS
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Salmonella Enteritidis ◽  
Sensory Characteristics ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Log Reduction

Iceberg lettuce is a major component in vegetable salad and has been associated with many outbreaks of foodborne illnesses. In this study, several combinations of lactic acid and hydrogen peroxide were tested to obtain effective antibacterial activity without adverse effects on sensory characteristics. A five-strain mixture of Escherichia coli O157:H7, Salmonella enterica serotype Enteritidis, and Listeria monocytogenes was inoculated separately onto fresh-cut lettuce leaves, which were later treated with 1.5% lactic acid plus 1.5% hydrogen peroxide (H2O2) at 40°C for 15 min, 1.5% lactic acid plus 2% H2O2 at 22°C for 5 min, and 2% H2O2 at 50°C for 60 or 90 s. Control lettuce leaves were treated with deionized water under the same conditions. A 4-log reduction was obtained for lettuce treated with the combinations of lactic acid and H2O2 for E. coli O157:H7 and Salmonella Enteritidis, and a 3-log reduction was obtained for L. monocytogenes. However, the sensory characteristics of lettuce were compromised by these treatments. The treatment of lettuce leaves with 2% H2O2 at 50°C was effective not only in reducing pathogenic bacteria but also in maintaining good sensory quality for up to 15 days. A ≤4-log reduction of E. coli O157:H7 and Salmonella Enteritidis was achieved with the 2% H2O2 treatment, whereas a 3-log reduction of L. monocytogenes was obtained. There was no significant difference (P &gt; 0.05) between pathogen population reductions obtained with 2% H2O2 with 60- and 90-s exposure times. Hydrogen peroxide residue was undetectable (the minimum level of sensitivity was 2 ppm) on lettuce surfaces after the treated lettuce was rinsed with cold water and centrifuged with a salad spinner. Hence, the treatment of lettuce with 2% H2O2 at 50°C for 60 s is effective in initially reducing substantial populations of foodborne pathogens and maintaining high product quality.

An in-vitro Comparison of the Bleaching Efficacy of 35 Percent Carbamide Peroxide with Established Intracoronal Bleaching Agents

2020 ◽  
Author(s):  
Nandita Bansal
Keyword(s):  
Hydrogen Peroxide ◽  
Sodium Perborate ◽  
Distilled Water ◽  
Carbamide Peroxide ◽  
Human Teeth ◽  
Anterior Teeth ◽  
Group I ◽  
Group Ii ◽  
Control Evaluation

Introduction: Intracoronal bleaching is the simplest, least invasive, and least expensive means available to lighten non-vital discolored teeth. The objective of the study: To evaluate the intra coronal bleaching efficacy of 35% Carbamide peroxide relative to 35% Hydrogen peroxide and Sodium perborate using artificially stained extracted human teeth. Materials and Methods: Eighty extracted human permanent maxillary and mandibular anterior teeth and single-rooted premolars were artificially stained using whole human blood and root canal treatment was completed. They were bleached twice 7 days apart using: Group I (n=20) – 35% Carbamide peroxide gel, Group II (n=20) – 35% Hydrogen peroxide gel, Group III (n=20) – 2 gm Sodium perborate mixed with per ml of distilled water, Group IV (n=20)– Distilled water only (control). Evaluation of shade was performed on day 0,7,14. Results: On day 7, In Groups I and Group II, there was a reduction in the shade by 2 vita tab positions, whereas Group IIIlightened by 1-tab position only. On day 14, CP and HP lightened by overall 3-tab positions and SP by 2-tab positions. There were no statistical differences between the groups on day 7 and day 14. Conclusion: 35% Carbamide peroxide, 35% Hydrogen peroxide and Sodiumperborate were equally effective for Intra coronal bleaching.

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