scholarly journals Development of a Test System To Evaluate Procedures for Decontamination of Respirators Containing Viral Droplets

2009 ◽  
Vol 75 (23) ◽  
pp. 7303-7309 ◽  
Author(s):  
Evanly Vo ◽  
Samy Rengasamy ◽  
Ronald Shaffer
Keyword(s):  
Uv Irradiation ◽  
Sodium Hypochlorite ◽  
Standard Method ◽  
Contact Time ◽  
Test System ◽  
Log Reduction ◽  
Pathogenic Viruses ◽  
Particle Counts ◽  
Particle Sizer ◽  
Higher Doses

ABSTRACT The aim of this study was to develop a test system to evaluate the effectiveness of procedures for decontamination of respirators contaminated with viral droplets. MS2 coliphage was used as a surrogate for pathogenic viruses. A viral droplet test system was constructed, and the size distribution of viral droplets loaded directly onto respirators was characterized using an aerodynamic particle sizer. The sizes ranged from 0.5 to 15 μm, and the sizes of the majority of the droplets were the range from 0.74 to 3.5 μm. The results also showed that the droplet test system generated similar droplet concentrations (particle counts) at different respirator locations. The test system was validated by studying the relative efficiencies of decontamination of sodium hypochlorite (bleach) and UV irradiation with droplets containing MS2 virus on filtering facepiece respirators. It was hypothesized that more potent decontamination treatments would result in corresponding larger decreases in the number of viable viruses recovered from the respirators. Sodium hypochlorite doses of 2.75 to 5.50 mg/liter with a 10-min decontamination period resulted in approximately 3- to 4-log reductions in the level of MS2 coliphage. When higher sodium hypochlorite doses (≥8.25 mg/liter) were used with the same contact time that was used for the dilute solutions containing 2.75 to 5.50 mg/liter, all MS2 was inactivated. For UV decontamination at a wavelength of 254 nm, an approximately 3-log reduction in the level of MS2 virus was achieved with dose of 4.32 J/cm2 (3 h of contact time with a UV intensity of 0.4 mW/cm2), while with higher doses of UV irradiation (≥7.20 J/cm2; UV intensity, 0.4 mW/cm2; contact times, ≥5 h), all MS2 was inactivated. These findings may lead to development of a standard method to test decontamination of respirators challenged by viral droplets.

scholarly journals Development of a Test System To Apply Virus-Containing Particles to Filtering Facepiece Respirators for the Evaluation of Decontamination Procedures

2009 ◽  
Vol 75 (6) ◽  
pp. 1500-1507 ◽  
Author(s):  
Edward Fisher ◽  
Samy Rengasamy ◽  
Dennis Viscusi ◽  
Evanly Vo ◽  
Ronald Shaffer
Keyword(s):  
Protective Factors ◽  
Sodium Hypochlorite ◽  
Protective Factor ◽  
Test System ◽  
Relative Standard ◽  
Pathogenic Viruses ◽  
Virucidal Efficacy ◽  
Different Levels ◽  
Insight Into

ABSTRACT A chamber to apply aerosolized virus-containing particles to air-permeable substrates (coupons) was constructed and validated as part of a method to assess the virucidal efficacy of decontamination procedures for filtering facepiece respirators. Coliphage MS2 was used as a surrogate for pathogenic viruses for confirmation of the efficacy of the bioaerosol respirator test system. The distribution of virus applied onto and within the coupons was characterized, and the repeatability of applying a targeted virus load was examined. The average viable virus loaded onto 90 coupons over the course of 5 days was found to be 5.09 ± 0.19 log10 PFU/coupon (relative standard deviation, 4%). To determine the ability to differentiate the effectiveness of disinfecting procedures with different levels of performance, sodium hypochlorite and steam treatments were tested in experiments by varying the dose and time, respectively. The role of protective factors was assessed by aerosolizing the virus with various concentrations of the aerosol-generating medium. A sodium hypochlorite (bleach) concentration of 0.6% and steam treatments of 45 s and longer resulted in log reductions (>4 logs) which reached the detection limits for both levels of protective factors. Organic matter (ATCC medium 271) as a protective factor afforded some protection to the virus in the sodium hypochlorite experiments but was not a factor in the steam experiments. The evaluation of the bioaerosol respirator test system demonstrated a repeatable method for applying a targeted viral load onto respirator coupons and provided insight into the properties of aerosols that are of importance to the development of disinfection assays for air-permeable materials.

scholarly journals Inactivation of Listeria monocytogenes ATCC 7644 on tomatoes using sodium dodecyl sulphate, levulinic acid and sodium hypochlorite solution

2015 ◽  
Author(s):  
◽  
Elizabeth Mnyandu
Keyword(s):  
Sodium Hypochlorite ◽  
Sodium Dodecyl Sulphate ◽  
Contact Time ◽  
Levulinic Acid ◽  
Fresh Produce ◽  
Sodium Dodecyl ◽  
Soluble Solids ◽  
Sodium Hypochlorite Solution ◽  
Hypochlorite Solution ◽  
Log Reduction

Listeria monocytogenes have been implicated as a public health concern worldwide. The study explored the survival of non-adapted, heat adapted and chlorine adapted L. monocytogenes on tomatoes; as well as the survival of non-adapted, heat adapted and chlorine adapted biofilms after exposure to sodium dodecyl sulphate (SDS), levulinc acid, sodium hypochlorite solution. Contact time of 1, 3 and 5 minutes was used. The survival of L. monocytogenes was monitored at 0, 24, 48 and 72 hours. The sanitizers were used individually or combined as follows; 1% sodium dodecyl sulphate individually; 0.5% levulinic acid individually; 200 ppm sodium hypochlorite solution individually and 0.5% levulinic acid/0.05% sodium dodecyl sulphate in combination (mixture). The samples were kept at 4 °C throughout the period of assessment. The effect of these sanitizers on pH, total soluble solids (TSS) and titratable acidity (TA) was also determined. Furthermore, the attachment of L. monocytogenes on tomatoes was investigated using a scanning electron microscope. Highest log reduction of non-adapted L. monocytogenes were observed on tomatoes treated with 1% SDS and least log reduction was achieved when tomatoes were treated with sodium hypochlorite solution. Though the log reduction achieved by 0.5% levulinic acid was higher that sodium hypochlorite solution, it was lower than log reduction achieved when 0.05% SDS / 0.5% levulinic acid mixture was used for all contact times. Using non-adapted L. monocytogenes, SDS was able to destroy all L. monocytogenes at 1, 3 and 5 minutes contact time. The trend was the same when heat adapted and chlorine adapted L. monocytogenes were used. There was no significant log reduction observed with biofilms. More favourable results were observed as contact time was increased from 1 to 5 minutes. Though there was a decrease in surviving bacteria from 1 to 3 minutes contact time, this decrease was not significant. The study investigated if exposure to sanitizer has an effect on pH, titratable acidity (TA) and total soluble solids (TSS) of the tomatoes. It was revealed that levulinic acid and mixture can have detrimental effect on pH, TA and TSS of tomatoes. The TA and TSS of samples treated with levulinic acid and mixture varied significantly (P ≤ 0.05) compared to the control sample. Although the TA and TSS of samples treated with SDS and sodium hypochlorite solution were different from the control, the differences were not significant. As much as sanitizers have the potential to reduce the bacterial population in fresh produce they may not completely destroy pathogens. Chlorine based sanitizers such as sodium hypochlorite though frequently used in the fresh produce industry, are not the best sanitizer to be used against food borne pathogens. Other sanitizers such as SDS used alone or in combination with another sanitizer can achieve better results than the widely used sodium hypochlorite solution as observed in this study. Stress adapted pathogens become less responsive to sanitizers during subsequent treatments. Through this research, it was established that biofilms are resistant to sanitizers. Though application of sanitizers in fresh produce is cheaper and simpler to apply, there is need to monitor varying concentrations of sanitizers, contact time and minimise contact with sub-surfaces as this could lead to sensory quality losses.

Ozonation of a secondary effluent both for fresh water protection and re-use

2006 ◽  
Vol 1 (2) ◽  
Author(s):  
M. Antonelli ◽  
V. Mezzanotte ◽  
C. Nurizzo
Keyword(s):  
Contact Time ◽  
Pilot Scale ◽  
Secondary Effluent ◽  
Water Protection ◽  
Faecal Coliforms ◽  
Colour Removal ◽  
E Coli ◽  
Log Reduction ◽  
Ionic Compounds ◽  
Higher Doses

49 trials were carried out at pilot scale to evaluate ozonation for polishing a nitrified and filtered effluent discharged in a brook, lying in a recreational protected area whose low and irregular flow provides a negligible dilution. Four ozone doses (3, 5, 7.5 and 10 mg O3/L) were tested and contact time was set at 10 minutes for each of the three contact columns. In most cases, at 3 mg O3/L, residual ozone concentration was below detection limit after 10 minutes contact time. For faecal coliforms and E. coli, log reduction increased from 3 mg O3/L to higher ozone doses, among which no appreciable difference was observed. No improvement in disinfection efficiency was seen for contact times over 10 minutes. Complete disinfection was obtained only in few cases, but final counts complying with the limits for discharge were always met. COD removal was low, while colour removal was significant and clearly increasing from 3 mg O3/L to higher doses. The removal of surfactants slightly increased with increasing dose for non ionic compounds, but not for anionic ones. Data confirmed that slight increases in ozone dose involve the release of bacterial organic matter which partially counterbalance the removal of COD.

Impact of Particulate Matter on Distribution System Disinfection Efficacy

2008 ◽  
Vol 43 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Linda Wojcicka ◽  
Carole Baxter ◽  
Ron Hofmann
Keyword(s):  
Helicobacter Pylori ◽  
Particulate Matter ◽  
Distribution System ◽  
Contact Time ◽  
Water Disinfection ◽  
Sphingomonas Paucimobilis ◽  
Soil Corrosion ◽  
Log Reduction ◽  
Drinking Water Disinfection ◽  
The Impact

Abstract Microorganisms have been shown to survive drinking water disinfection and remain viable in disinfected waters despite the presence of disinfectant residuals. This may be partially attributed to protection by particulate matter. The aim of this study was to determine the effects of the presence of particulate matter on disinfection kinetics. Sphingomonas paucimobilis ATCC 10829 and Helicobacter pylori ATCC 43504 were used in inactivation experiments in the presence and absence of soil, corrosion, and wastewater particles. The results showed that the presence of such particles tended to inhibit chlorine and monochloramine inactivation, although the magnitude of the impact under the conditions tested was small (e.g., 1-log reduction in inactivation for several minutes of contact time in the presence of less than 1 mg/L of disinfectant).

scholarly journals Repeatability and Reproducibility of Germicide Tests: A Literature Review

1999 ◽  
Vol 82 (2) ◽  
pp. 384-389 ◽  
Author(s):  
Nicola Tilt ◽  
Martin A Hamilton
Keyword(s):  
Literature Review ◽  
Standard Method ◽  
Collaborative Study ◽  
Hard Surface ◽  
Log Reduction ◽  
Repeatability And Reproducibility ◽  
Standard Deviations ◽  
Antimicrobial Assay

Abstract The results of a quantitative antimicrobial assay can be summarized by the log reduction value. For an assay to be proposed as a standard method, it is usually necessary to conduct a collaborative study to demonstrate that the repeatability and reproducibility standard deviations (SDs) of the log reduction values are sufficiently small. It is not clear, however, precisely how small those SDs should be. This paper describes the results of a literature review conducted to determine the range of repeatability and reproducibility SDs for standard quantitative antimicrobial assays. The underlying premise is that, for an assay to have been accepted as a standard method, its repeatability and reproducibility SDs must have been sufficiently small. This premise implies that the repeatability and reproducibility SDs of standard assays establish de facto guidelines for acceptability. The survey comprised papers where the SDs could be extracted directly or where they could be calculated from accessible data. Papers describing suspension tests as well as hard surface tests were included. For the standard antimicrobial assays reviewed, repeatability SDs ranged from 0.25 to 1.21 and the reproducibility SDs ranged from 0.31 to 1.54.

scholarly journals Inactivation of Multi-Drug Resistant Non-Typhoidal Salmonella and Wild-Type Escherichia coli STEC Using Organic Acids: A Potential Alternative to the Food Industry

Pathogens ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 849
Author(s):  
Vinicius Silva Castro ◽  
Yhan da Silva Mutz ◽  
Denes Kaic Alves Rosario ◽  
Adelino Cunha-Neto ◽  
Eduardo Eustáquio de Souza Figueiredo ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Acetic Acid ◽  
Organic Acids ◽  
Sodium Hypochlorite ◽  
Bacterial Species ◽  
Disk Diffusion ◽  
Clinical Strains ◽  
Linear Pattern ◽  
E Coli ◽  
Log Reduction

Salmonella and Escherichia coli are the main bacterial species involved in food outbreaks worldwide. Recent reports showed that chemical sanitizers commonly used to control these pathogens could induce antibiotic resistance. Therefore, this study aimed to describe the efficiency of chemical sanitizers and organic acids when inactivating wild and clinical strains of Salmonella and E. coli, targeting a 4-log reduction. To achieve this goal, three methods were applied. (i) Disk-diffusion challenge for organic acids. (ii) Determination of MIC for two acids (acetic and lactic), as well as two sanitizers (quaternary compound and sodium hypochlorite). (iii) The development of inactivation models from the previously defined concentrations. In disk-diffusion, the results indicated that wild strains have higher resistance potential when compared to clinical strains. Regarding the models, quaternary ammonium and lactic acid showed a linear pattern of inactivation, while sodium hypochlorite had a linear pattern with tail dispersion, and acetic acid has Weibull dispersion to E. coli. The concentration to 4-log reduction differed from Salmonella and E. coli in acetic acid and sodium hypochlorite. The use of organic acids is an alternative method for antimicrobial control. Our study indicates the levels of organic acids and sanitizers to be used in the inactivation of emerging foodborne pathogens.

scholarly journals Sodium hypochlorite dosage for household and emergency water treatment: updated recommendations

2017 ◽  
Vol 16 (1) ◽  
pp. 112-125 ◽  
Author(s):  
Natalie Wilhelm ◽  
Anya Kaufmann ◽  
Elizabeth Blanton ◽  
Daniele Lantagne
Keyword(s):  
Water Treatment ◽  
Sodium Hypochlorite ◽  
Diarrheal Disease ◽  
Microbiological Quality ◽  
Water Source ◽  
Field Studies ◽  
Household Water Treatment ◽  
E Coli ◽  
Log Reduction ◽  
Household Water

Abstract Household water treatment with chlorine can improve the microbiological quality of household water and reduce diarrheal disease. We conducted laboratory and field studies to inform chlorine dosage recommendations. In the laboratory, reactors of varying turbidity (10–300 NTU) and total organic carbon (0–25 mg/L addition) were created, spiked with Escherichia coli, and dosed with 3.75 mg/L sodium hypochlorite. All reactors had >4 log reduction of E. coli 24 hours after chlorine addition. In the field, we tested 158 sources in 22 countries for chlorine demand. A 1.88 mg/L dosage for water from improved sources of <5 or <10 NTU turbidity met free chlorine residual criteria (≤2.0 mg/L at 1 hour, ≥0.2 mg/L at 24 hours) 91–94% and 82–87% of the time at 8 and 24 hours, respectively. In unimproved water source samples, a 3.75 mg/L dosage met relaxed criteria (≤4.0 mg/L at 1 hour, ≥0.2 mg/L after 24 hours) 83% and 65% of the time after 8 and 24 hours, respectively. We recommend water from improved/low turbidity sources be dosed at 1.88 mg/L and used within 24 hours, and from unimproved/higher turbidity sources be dosed at 3.75 mg/L and consumed within 8 hours. Further research on field effectiveness of chlorination is recommended.

Reduction of Microbial Pathogens during Apple Cider Production Using Sodium Hypochlorite, Copper Ion, and Sonication

2004 ◽  
Vol 67 (4) ◽  
pp. 766-771 ◽  
Author(s):  
STEPHANIE L. RODGERS ◽  
ELLIOT T. RYSER
Keyword(s):  
Sodium Hypochlorite ◽  
Copper Ion ◽  
Microbial Pathogens ◽  
Sodium Hypochlorite Solution ◽  
Escherichia Coli O157 ◽  
Hypochlorite Solution ◽  
Apple Cider ◽  
E Coli ◽  
Log Reduction ◽  
Pathogen Reduction

Sodium hypochlorite (100 ppm), copper ion water (1 ppm), and sonication (22 to 44 kHz and 44 to 48 kHz) were assessed individually and in combination for their ability to reduce populations of Escherichia coli O157:H7 and Listeria monocytogenes on apples and in apple cider. Commercial unpasteurized cider was inoculated to contain approximately 106 CFU/ml of either pathogen and then sonicated at 44 to 48 kHz, with aliquots removed at intervals of 30 to 60 s for up to 5 min and plated to determine numbers of survivors. Subsequently, whole apples were inoculated by dipping to contain approximately 106 CFU/g E. coli O157:H7 or L. monocytogenes, held overnight, and then submerged in 1 ppm copper ion water with or without 100 ppm sodium hypochlorite for 3 min with or without sonication at 22 to 44 kHz and examined for survivors. Treated apples were also juiced, with the resulting cider sonicated for 3 min. Populations of both pathogens decreased 1 to 2 log CFU/ml in inoculated cider following 3 min of sonication. Copper ion water alone did not significantly reduce populations of either pathogen on inoculated apples. However, when used in combination with sodium hypochlorite, pathogen levels decreased approximately 2.3 log CFU/g on apples. Sonication of this copper ion–sodium hypochlorite solution at 22 to 44 kHz did not further improve pathogen reduction on apples. Numbers of either pathogen in the juice fraction were approximately 1.2 log CFU/ml lower after being juiced, with sonication (44 to 48 kHz) of the expressed juice decreasing L. monocytogenes and E. coli O157:H7 populations an additional 2 log. Hence, a 5-log reduction was achievable for both pathogens with the use of copper ion water in combination with sodium hypochlorite followed by juicing and sonication at 44 to 48 kHz.

High resistance of fish pathogenic viruses to UV irradiation and ozonated seawater

2006 ◽  
Vol 34 (2) ◽  
pp. 72-82 ◽  
Author(s):  
H. Liltved ◽  
C. Vogelsang ◽  
I. Modahl ◽  
B.H. Dannevig
Keyword(s):  
Uv Irradiation ◽  
High Resistance ◽  
Pathogenic Viruses

scholarly journals Subcutaneous Implants of Buprenorphine-Cholesterol-Triglyceride Powder in Mice

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
L. DeTolla ◽  
R. Sanchez ◽  
E. Khan ◽  
B. Tyler ◽  
M. Guarnieri
Keyword(s):  
Clinical Pathology ◽  
Test System ◽  
Clinical Observations ◽  
Safety Test ◽  
Term Delivery ◽  
Low Toxicity ◽  
Animal Safety ◽  
Higher Doses ◽  
Drug Implants

Subcutaneous drug implants are convenient systems for the long-term delivery of drugs in animals. Lipid carriers are logical tools because they generally allow for higher doses and low toxicity. The present study used an US Food and Drug Administration Target Animal Safety test system to evaluate the safety of a subcutaneous implant of a cholesterol-triglyceride-buprenorphine powder in 120 BALB/c mice. Mice were evaluated in 4- and 12-day trials with 1- and 5-fold doses of the intended 3 mg/kg dose of drug. One male mouse treated with three 3 mg/kg doses and surgery on days 0, 4, and 8 died on day 9. The cause of death was not determined. In the surviving 119 mice there was no evidence of skin reaction at the site of the implant. Compared to control animals treated with saline, weight measurements, clinical pathology, histopathology, and clinical observations were unremarkable. These results demonstrate that the lipid carrier is substantially safe. Cholesterol-triglyceride-drug powders may provide a valuable research tool for studies of analgesic and inflammatory drug implants in veterinary medicine.

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