scholarly journals Theoretical and Experimental Aspects of Microbicidal Activities of Hard Surface Disinfectants: Are Their Label Claims Based on Testing Under Field Conditions?

2010 ◽  
Vol 93 (6) ◽  
pp. 1944-1951 ◽  
Author(s):  
Navid Omidbakhsh
Keyword(s):  
Contact Time ◽  
Performance Criterion ◽  
Log10 Reduction ◽  
Single Application ◽  
Hard Surface ◽  
Environmental Surfaces ◽  
Label Claim ◽  
Chlorine Bleach ◽  
Carrier Test ◽  
Ammonium Compounds

Abstract High-touch environmental surfaces are important in the spread of many nosocomial pathogens. Although such surfaces are routinely disinfected, the testing and label claims of many common disinfectants do not reflect the realities of field use. A study was conducted to determine the influence of several crucial factors on the action of disinfectants in general, and to assess the killing efficiency of selected chemistries against Staphylococcus aureus and Pseudomonas aeruginosa, related to their drying times (i.e., after one application) and label-specified contact times using a quantitative carrier test. The products were also tested for their ability to wet a hydrophobic (epoxy resin) surface. The hard-surface disinfectants (in-use concentration in ppm) tested were: (a) chlorine bleach (500); (b) quaternary ammonium compounds (quat; 600) alone; (c) quat (3000) with 17 isopropanol (v/v); (d) quat (3000) with 60 ethanol (v/v); (e) phenolic (800) alone; (f) quat (2000), phenolic (3000) with 70 ethanol (v/v); and (g) accelerated hydrogen peroxide (AHP; 5000 of H2O2). The arbitrarily set criterion of bactericidal activity was 6 log10 reduction in the viability of both species tested. All surfaces tested with all products dried in <5 min, with alcohol-based surfaces drying significantly faster. Even though the alcohol-free quat and phenolic claim a contact time of 10 min, they dried in <4 min after a single application and failed to meet the performance criterion. Bleach (500 ppm) dried in about 3 min and was effective. AHP also dried in about 3 min and met its label claim even at 1 min of contact. Quat (3000) with 17 isopropanol dried at 1 min and was effective. Quat (3000) with 60 ethanol and quat (2000), phenolic (3000) with 70 ethanol dried in <1 min, and were ineffective. AHP, alcohol-containing quats, and quat-phenolic-alcohol gave acceptable wettability, while quat and phenolic alone, as well as bleach, covered the treated surface unevenly. The findings show that label claims, especially those for contact times, fail to reflect the way many hard-surface disinfectants are used in the field.

scholarly journals Application of EN 16615 (4-Field Test) for the Evaluation of the Antimicrobial Activity of the Selected Commercial and Self-Made Disinfectant Wipes

2021 ◽  
Vol 18 (11) ◽  
pp. 5932
Author(s):  
Stefan Tyski ◽  
Wanda Grzybowska ◽  
Ewa Bocian
Keyword(s):  
Antimicrobial Activity ◽  
Field Test ◽  
Sodium Hypochlorite ◽  
Contact Time ◽  
Multidrug Resistant ◽  
Log10 Reduction ◽  
Disinfection Process ◽  
Microbial Strains ◽  
First Time ◽  
Ammonium Compounds

The purpose of disinfectants is to reduce microorganisms on a contaminated surface and to prevent the spread of microorganisms. The relatively new EN 16615 simulates disinfection by wiping and allows for assessing the recovery of microorganisms from the surface and, importantly, the degree of spread of microorganisms when the surface is disinfected by wiping. For the first time, using this standard, the tested products in the form of commercial disinfectant wipes were compared with self-made wipes soaked in respective disinfectant liquids. The disinfected surfaces were simulated by homogeneous polyvinyl chloride plates. The studies were carried out not only with the standard, but also with clinical multidrug-resistant microbial strains. Based on the research, it can be concluded that the most effective products in the disinfection process (log10 reduction of ≥5) with the shortest contact time (1 min) were products containing ethanol, propanol, and quaternary ammonium compounds (self-made wipes) and propanol (commercial wipes). The least effective products (log10 reduction of <5) in terms of the contact time declared by the manufacturer were products containing ethanol and sodium hypochlorite (commercial wipes). Much better antimicrobial activity of self-made wipes was observed in comparison to the activity of the commercial wipes.

Effect of Temperature and Contact Time on the Activity of Eight Disinfectants - A Classification

1984 ◽  
Vol 47 (11) ◽  
pp. 841-847 ◽  
Author(s):  
P. GÉLINAS ◽  
J. GOULET ◽  
G. M. TASTAYRE ◽  
G. A. PICARD
Keyword(s):  
Quaternary Ammonium ◽  
Contact Time ◽  
Test Organism ◽  
Amphoteric Surfactant ◽  
Effect Of Temperature ◽  
Dilution Method ◽  
Ammonium Compound ◽  
Optimum Growth Temperature ◽  
Ammonium Compounds

The combined influence of temperature (4, 20, 37 and 50°C) and contact time (10, 20 and 30 min) on the efficacy of eight commercial disinfectants was evaluated by the Association of Official Analytical Chemists use-dilution method. An increase of temperature greatly enhanced the activity of all tested solutions, particularly glutaraldehyde, chlorhexidine acetate and the amphoteric surfactant, whereas contact time mainly enhanced the efficacy of sodium hypochlorite, the quaternary ammonium compound and the amphoteric surfactant. Temperature and contact time influenced the activity profile of the disinfectants tested, with a maximum efficacy near the optimum growth temperature (37°C) of the test organism (Pseudomonas aeruginosa ATCC 15442). This organism was highly resistant to the amphoteric surfactant as well as to the two quaternary ammonium compounds. Classification of disinfectants is proposed on the basis of their mode of action, temperature dependence and activation energies, heat and light stability, and tolerance to organic matter.

Selection Process of Phytochemicals and Efficacy of Thymol, Eugenol and Calcium Ferulate on Heterotrophic Plate Count Bacteria in Water

2019 ◽  
Vol 41 (2) ◽  
pp. 345-345
Author(s):  
Humayun Wali and Muhammad Zafar Humayun Wali and Muhammad Zafar
Keyword(s):  
Contact Time ◽  
Water Solubility ◽  
Linear Models ◽  
Selection Process ◽  
Antimicrobial Properties ◽  
Temperature Treatment ◽  
Plate Count ◽  
Log10 Reduction ◽  
Heterotrophic Plate Count ◽  
Treatment Groups

Water samples of Lahore Canal have been tested for log reduction of heterotrophic plate count microorganisms in the presence of three selected phytochemicals: thymol, eugenol and freshly prepared calcium salt of ferulic acid. Thymol results in about 0.9 log10 reduction (at 80 min contact time), 1.2 log10 reduction (at 90 min contact) and 2.6 log10 reduction (contact time: 60 min) for 75, 150 and 300 ppm wt./wt. phytochemical in water sample respectively. Eugenol at 150 and 300 ppm is as good as thymol for log10 reduction, but not at 75 ppm. Calcium ferulate does not significantly reduce the heterotrophic plate count microorganisms at the three tested concentrations. Contact time is found crucial for optimum reduction of microorganisms. Further studies have been carried out for thymol at 50 ppm. It is observed that thymol results in 0.9 log10 reduction at pH 9.5 and 30oC. At this concentration and at 13oC and 20oC, significant decrease in heterotrophic plate count is not observed at either pH 4.5, 7.0, and 9.5. Contact time is again important for inactivating the microorganisms. Statistical analysis is made to evaluate differences between the phytochemical-time in concentration treatment groups and pH-time in the temperature treatment groups. Two linear models of thymol reduction of heterotrophic plate count microorganisms are developed to study the relationships between the variables responsible for inactivation. Where experimental data is not available, software PASS, GUSAR, EPI Suite and Marvin Sketch are used to predict antimicrobial properties, toxicity and water solubility. Based on these criteria, affordability and aesthetics, the final selection of phytochemicals is made.

scholarly journals Identification by Quantitative Carrier Test of Surrogate Spore-Forming Bacteria To Assess Sporicidal Chemicals for Use against Bacillus anthracis

2007 ◽  
Vol 74 (3) ◽  
pp. 676-681 ◽  
Author(s):  
Miles R. Majcher ◽  
Kathryn A. Bernard ◽  
Syed A. Sattar
Keyword(s):  
Bacillus Anthracis ◽  
Contact Time ◽  
Room Temperature ◽  
Final Analysis ◽  
Viable Spore ◽  
Heat Treated ◽  
Liquid Chemical ◽  
Second Tier ◽  
Carrier Test ◽  
Spore Forming Bacteria

ABSTRACT The spores of six strains of Bacillus anthracis (four virulent and two avirulent) were compared with those of four other types of spore-forming bacteria for their resistance to four liquid chemical sporicides (sodium hypochlorite at 5,000 ppm available chlorine, 70,000 ppm accelerated H2O2, 1,000 ppm chlorine dioxide, and 3,000 ppm peracetic acid). All test bacteria were grown in a 1:10 dilution of Columbia broth (with manganese) incubated at 37°C for 72 h. The spore suspensions, heat treated at 80°C for 10 min to rid them of any viable vegetative cells, contained 1 × 108 to 3 × 108 CFU/ml. The second tier of the quantitative carrier test (QCT-2), a standard of ASTM International, was used to assess for sporicidal activity, with disks (1 cm in diameter) of brushed and magnetized stainless steel as spore carriers. Each carrier, with 10 μl (≥106 CFU) of the test spore suspension in a soil load, was dried and then overlaid with 50 μl of the sporicide being evaluated. The contact time at room temperature ranged from 5 to 20 min, and the arbitrarily set criterion for acceptable sporicidal activity was a reduction of ≥106 in viable spore count. Each test was repeated at least three times. In the final analysis, the spores of Bacillus licheniformis (ATCC 14580T) and Bacillus subtilis (ATCC 6051T) proved to be generally more resistant than the spores of the strains of B. anthracis tested. The use of one or both of the safe and easy-to-handle surrogates identified here should help in developing safer and more-effective sporicides and also in evaluating the field effectiveness of existing and newer formulations in the decontamination of objects and surfaces suspected of B. anthracis contamination.

Hard Surface Carrier Test for Efficacy Testing of Disinfectants: Collaborative Study

1992 ◽  
Vol 75 (4) ◽  
pp. 635-645 ◽  
Author(s):  
Joseph R Rubino ◽  
Janice M Bauer ◽  
Paul H Clarke ◽  
Betsy B Woodward ◽  
Fran C Porter ◽  
...  
Keyword(s):  
Statistical Significance ◽  
Collaborative Study ◽  
The Other ◽  
Performance Standard ◽  
Hard Surface ◽  
Upper Confidence Limit ◽  
Significant Difference ◽  
Negative Controls ◽  
Carrier Test ◽  
Good Agreement

Abstract A collaborative study was undertaken to evaluate a new disinfectant efficacy method called the hard surface carrier test. This new method is a qualitative carrier test that uses disposable glass carriers and standardized bacterial cultures. Ten laboratories tested 6 disinfectant-type formulations, which included positive and negative controls, against 3 microorganisms. No significant differences were found among the 10 laboratories for tests with Pseudomonas aeruginosa and Salmonella choleraesuis, but a small but statistically significant difference was present among laboratories for Staphylococcus aureus. The majority of data for this organism showed very good agreement; however, several tests exhibited slightly higher positive responses, which resulted in this overall difference. This difference was not considered significant within the scope and precision of this method or when compared with results for the other 2 organisms. The initial estimates of pure intralaboratory variance, determined from mean squares from analysis of variance results, were 1.009,0.295, and 1.553 for P. aeruginosa, S. aureus, and S. choleraesuis, respectively. The experimental error for S. aureus was 3-5 times smaller than for the other 2 organisms, which helps explain the statistical significance of the results observed with this organism. Final estimates of intralaboratory variance obtained after dropping nonsignificant terms from the models were 0.90,0.30, and 0.58 for P. aeruginosa, S. aureus, and S. choleraesuis, respectively. Small but statistically significant differences were noted in the formulation means for P. aeruginosa and S. aureus but not for S. choleraesuis. The results of this study suggested a performance standard of ≤2 positive carriers out of 60 tested for S. aureus and S. choleraesuis, and ≤3 positive carriers out of 60 tested for P. aeruginosa. This standard was derived from an analysis of the data by calculating an expected count of positive carriers and a 95% upper confidence limit for a set of 60 carriers. The method has been adopted first action by AOAC International.

Terminal Decontamination of Patient Rooms Using an Automated Mobile UV Light Unit

2011 ◽  
Vol 32 (8) ◽  
pp. 737-742 ◽  
Author(s):  
John M. Boyce ◽  
Nancy L. Havill ◽  
Brent A. Moore
Keyword(s):  
Uv Light ◽  
Patient Discharge ◽  
Test Method ◽  
Cycle Times ◽  
Ozone Concentrations ◽  
Environmental Surfaces ◽  
Before And After ◽  
American Society ◽  
Carrier Test ◽  
Uv C

Objective.To determine the ability of a mobile UV light unit to reduce bacterial contamination of environmental surfaces in patient rooms.Methods.An automated mobile UV light unit that emits UV-C light was placed in 25 patient rooms after patient discharge and operated using a 1- or 2-stage procedure. Aerobic colony counts were calculated for each of 5 standardized high-touch surfaces in the rooms before and after UV light decontamination (UVLD). Clostridium difficile spore log reductions achieved were determined using a modification of the ASTM (American Society for Testing and Materials) International E2197 quantitative disk carrier test method. In-room ozone concentrations during UVLD were measured.Results.For the 1-stage procedure, mean aerobic colony counts for the 5 high-touch surfaces ranged from 10.6 to 98.2 colony-forming units (CFUs) per Dey/Engley (D/E) plate before UVLD and from 0.3 to 24.0 CFUs per D/E plate after UVLD, with significant reductions for all 5 surfaces (all P<.02). Surfaces in direct line of sight were significantly more likely to yield negative culture results after UVLD than before UVLD (all P<.001). Mean C. difficile spore log reductions ranged from 1.8 to 2.9. UVLD cycle times ranged from 34.2 to 100.1 minutes. For the 2-stage procedure, mean aerobic colony counts ranged from 10.0 to 89.2 CFUs per D/E plate before UVLD and were 0 CFUs per D/E plate after UVLD, with significant reductions for all 5 high-touch surfaces. UVLD cycle times ranged from 72.1 to 146.3 minutes. In-room ozone concentrations during UVLD ranged from undetectable to 0.012 ppm.Conclusions.The mobile UV-C light unit significantly reduced aerobic colony counts and C. difficile spores on contaminated surfaces in patient rooms.

scholarly journals Is routine disinfection efficient in preventing contamination with Toxocara canis eggs?

2019 ◽  
Vol 94 ◽  
Author(s):  
A.L. Ursache ◽  
V. Mircean ◽  
M. Dumitrache ◽  
S. Andrei ◽  
L. Ştefănuţ ◽  
...  
Keyword(s):  
Contact Time ◽  
Toxocara Canis ◽  
Inhibitory Effect ◽  
Public Health Importance ◽  
Sodium Dichloroisocyanurate ◽  
Didecyldimethylammonium Chloride ◽  
Household Cleaning ◽  
Household Cleaning Products ◽  
Ammonium Compounds ◽  
Great Public Health

Abstract Toxocara canis (Werner, 1782) is a zoonotic nematode commonly parasitizing dogs worldwide with great public health importance as the aetiological agent of human toxocariasis. In this respect, the aim of this study was to evaluate the effect of six disinfectant products commonly used in kennels, veterinary clinics and as household cleaning products on the embryogenesis and viability of T. canis eggs. The composition of active ingredients in these commercial disinfectants was sodium hypochlorite (A); a mix of N-(3-aminopropyl)-N-dodecylpropan-1.3-diamine and didecyldimethylammonium chloride (B); sodium dichloroisocyanurate dehydrate (C); a mix of glutaraldehyde, quaternary ammonium compounds, benzyl-c12-18-alkyldimethyl and chlorides (D); a mix of 2-propanol, ethanol, benzalkonium chloride and glucoprotamin (E); a mix of pentapotassium bis (peroxymonosulphate) bis (sulphate), sodium C10-13-alkylbenzenesulphonate, malic acid, sulphamidic acid, sodium toluenesulphonate, dipotassium peroxodisulphate and dipentene (F). After dilution, the tested disinfectants had the maximal concentration recommended by the manufacturer in order to achieve a biocidal effect. Each product was tested on approximately 10,000 T. canis eggs, having five different contact times (5, 10, 15, 30, 60 min). Three replicates were tested for each diluted disinfectant and for each contact time. After the treatment, eggs were washed and incubated in distilled water at 27 °C for 2 weeks. None of the tested products had a significant inhibitory effect on the embryogenesis and viability of T. canis eggs, regardless of the contact time. Moreover, after 2 weeks, in all tested samples, eggs containing motile infective larvae were identified, showing that routinely used disinfectants do not eliminate risk of infection by T. canis.

Effect of Suspended Solids on Inactivation of Poliovirus and T2-Phage by Ozone

1989 ◽  
Vol 21 (3) ◽  
pp. 215-219 ◽  
Author(s):  
Mitsumi Kaneko
Keyword(s):  
Activated Sludge ◽  
Contact Time ◽  
Model Equation ◽  
Suspended Solids ◽  
Virus Inactivation ◽  
Large Reduction ◽  
Log10 Reduction ◽  
Applied Dose ◽  
Using Data ◽  
Logarithmic Reduction

This study was conducted to quantify the effects of suspended solids on virus inactivation by ozone and to develop guidelines for ozone dosages in disinfection using poliovirus and T2-phage. The curve of virus count reduction could be divided into three phases: an initial large reduction which occurred within 30 seconds of contact between the viruses and ozone; a subsequent logarithmic reduction; and finally, a slow reduction in response to decreasing ozone concentrations. The reduction of the viruses by ozone is expressed well by the Collins-Selleck Model. The presence of suspended solids significantly reduced the rate of virus inactivation. Using data obtained in this study, the model equation gives the following estimates: if 99.99% inactivation is required with a contact time of 5 minutes, an ozone residual of 0.6 mg/l is necessary when suspended solids are not present; with kaolin levels of 1 and 10 mg/l, ozone residuals of at least 0.9 and 3.7 mg/l, respectively, are necessary for 99.99% inactivation in 5 minutes. If more than 1 mg/l of an autoclaved activated sludge is added to the water, the commonly applied dose of ozone is not sufficient to produce more than a 4 log10 reduction in 5 minutes.

scholarly journals Disinfectant Performance of a Chlorine Regenerable Antibacterial Microfiber Fabric as a Reusable Wiper

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 127 ◽  
Author(s):  
Cheng Huang ◽  
Yongbang Chen ◽  
Gang Sun ◽  
Kelu Yan
Keyword(s):  
Contact Time ◽  
Graft Polymerization ◽  
Ph Value ◽  
University Student ◽  
Polymerization Process ◽  
Sodium Hypochlorite Solution ◽  
Polyester Fibers ◽  
Actual Use ◽  
Chlorine Bleach ◽  
Temperature Time

Rechargeable disinfectant performance of a microfiber fabric grafted with a halamine precursor, 3-allyl-5,5-dimethylhydantoin (ADMH), was tested in an actual use situation in a university student dining hall. The precursor was successfully incorporated onto the surfaces of polyester fibers by using a radical graft polymerization process through a commercial finishing facility. The N–H bonds of ADMH moieties on the fibers can be converted to biocidal N–Cl bonds, when the fabrics are washed in a diluted chlorine bleach containing 3000 ppm available chlorine, providing a refreshable disinfectant function. By wiping the surfaces of 30 tables (equivalent to 18 m2) with wet chlorinated fabrics, both Staphylococcus aureus and Escherichia coli in concentrations of 105 CFU/mL were totally killed in a contact time of 3 min. The disinfectant properties of the fabrics were still superior after 10 times successive machine washes (equivalent to fifty household machine washes), and rechargeable after wiping 30 tables before each recharge. Recharging conditions, such as temperature, time, active chlorine concentration and pH value of sodium hypochlorite solution, as well as the addition of a detergent, were studied. The product has the potential to improve public safety against biological contaminations and the transmission of diseases.

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