scholarly journals Quantitation of Risk Reduction of E. coli Transmission after Using Antimicrobial Hand Soap

Pathogens ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 778
Author(s):  
Umesh Adhikari ◽  
Elaheh Esfahanian ◽  
Jade Mitchell ◽  
Duane Charbonneau ◽  
Xiangyu Song ◽  
...  
Keyword(s):  
Hand Washing ◽  
Food Preparation ◽  
Quantitative Microbial Risk Assessment ◽  
Risk Of Infection ◽  
Indirect Contact ◽  
Microbial Risk Assessment ◽  
E Coli ◽  
Indirect Transmission ◽  
Escherichia Coli Infection ◽  
Handwashing With Soap

Handwashing with soap is an effective and economical means to reduce the likelihood of Escherichia coli infection from indirect contact with contaminated surfaces during food preparation. The purpose of this study was to conduct a quantitative microbial risk assessment (QMRA) to evaluate the risk of infection from indirect contact with fomites contaminated with E. coli after hand washing with antimicrobial hand soaps. A Monte Carlo simulation was done with a total of 10,000 simulations to compare the effectiveness of two antimicrobial and one control (non-antimicrobial) bar soaps in reducing the exposure and infection risk compared to no hand washing. The numbers of E. coli on several fomites commonly found in household kitchens, as well as the transfer rates between fomites and onto fingertips, were collected from the literature and experimental data. The sponsor company provided the E. coli survival on hands after washing with antimicrobial and control soaps. A number of scenarios were evaluated at two different exposure doses (high and low). Exposure scenarios included transfer of E. coli between meat-to-cutting board surface-to-hands, meat-to-knife surface-to-hands, and from a countertop surface-to-hands, kitchen sponge-to-hands, hand towel-to-hands, and dishcloth-to-hands. Results showed that the risks of illness after washing with the control soap was reduced approximately 5-fold compared to no handwashing. Washing with antimicrobial soap reduced the risk of E. coli infection by an average of about 40-fold compared with no handwashing. The antimicrobial soaps ranged from 3 to 32 times more effective than the non-antimicrobial soap, depending on the specific exposure scenario. Importance: The Centers for Disease Control and Prevention indicate the yearly incidence rate of Shiga Toxin producing E. coli infections is about 1.7/100,000, with about 10% of cases leading to life-threatening hemolytic uremic syndrome and 3–5% leading to death. Our findings confirm handwashing with soap reduces the risks associated with indirect transmission of E. coli infection from contact with fomites during food preparation. Further, in these exposure scenarios, antimicrobial soaps were more effective overall than the non-antimicrobial soap in reducing exposure to E. coli and risk of infection.

Assessment of microbial infection risks posed by ingestion of water during domestic water use and full-contact recreation in a mid-southern African region

2004 ◽  
Vol 50 (1) ◽  
pp. 301-308 ◽  
Author(s):  
M. Steyn ◽  
P. Jagals ◽  
B. Genthe
Keyword(s):  
Risk Assessment ◽  
Quantitative Microbial Risk Assessment ◽  
Risk Of Infection ◽  
Single Exposure ◽  
Domestic Water ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
E Coli ◽  
Full Contact ◽  
Contact Recreation

A customised Water-related Quantitative Microbial Risk Assessment (WRQMRA) process was used to determine risk of infection to water ingested by users in the south-eastern Free State, South Africa. The WRQMRA consisted of an observed-adverse-effect-level approach (OAELA) and a quantitative microbial risk assessment (QMRA). The OAELA was based on the occurrence of E. coli in the study waters to determine the possible risk of infection and the QMRA probable risk of infection by salmonellae. The WRQMRA was applied to recreational surface resource waters as well as waters from an unprotected spring and waters from the treated municipal supply that were stored in containers for domestic purposes. E. coli numbers were measured against expected infection levels expressed in water quality guidelines, while Salmonella counts were calculated to give the probable infection risk (Pi). Ingestion was based on intake volumes compiled for the various water uses. E. coli occurred in numbers <106 in the surface waters, while the untreated spring and treated supply water contained E. coli of <102 and <101 respectively. Salmonella occurred in numbers of <103 in recreational waters, and <10-1 in water used for domestic purposes. A single exposure to the mean (as well as 95th percentile) risk was calculated using a β-Poisson dose-response model at ingestion volumes of 100 mL (for full-contact recreation) and 1,318 mL (for domestic water use). Both the OAELA and the QMRA approaches indicated a risk of infection to recreational and domestic water users, even for a single exposure event, with the OAELA either over- or under-estimating the risk of infection for singular exposure events. This indicated that this method, used on its own, could not reliably predict a realistic risk of infection. It is recommended that the full WRQMRA process be used, and further developed to address several uncertainties that became evident during this study.

scholarly journals Microbial risk assessment of local handling and use of human faeces

2006 ◽  
Vol 5 (1) ◽  
pp. 117-128 ◽  
Author(s):  
Caroline Schönning ◽  
Therese Westrell ◽  
Thor Axel Stenström ◽  
Karsten Arnbjerg-Nielsen ◽  
Arne Bernt Hasling ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Incidence Rates ◽  
Quantitative Microbial Risk Assessment ◽  
Risk Of Infection ◽  
Accidental Ingestion ◽  
Storage Container ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Local Use ◽  
Annual Risk

Dry urine-diverting toilets may be used in order to collect excreta for the utilisation of nutrients. A quantitative microbial risk assessment was conducted in order to evaluate the risks of transmission of infectious disease related to the local use of faeces as a fertiliser. The human exposures evaluated included accidental ingestion of small amounts of faeces, or a mixture of faeces and soil, while emptying the storage container and applying the material in the garden, during recreational stays to the garden, and during gardening. A range of pathogens representing various groups of microorganisms was considered. Results showed that 12-months' storage before use was sufficient for the inactivation of most pathogens to acceptable levels. When working or spending time in the garden the annual risk of infection by Ascaris was still slightly above 10-4 in these scenarios, although the incidence rate for Ascaris is very low in the population in question. Measures to further reduce the hygienic risks include longer storage, or treatment, of the faeces. The results can easily be extended to other regions with different incidence rates.

scholarly journals Quantitative Microbial Risk Assessment Models for Consumption of Raw Vegetables Irrigated with Reclaimed Water

2006 ◽  
Vol 72 (5) ◽  
pp. 3284-3290 ◽  
Author(s):  
Andrew J. Hamilton ◽  
Frank Stagnitti ◽  
Robert Premier ◽  
Anne-Maree Boland ◽  
Glenn Hale
Keyword(s):  
Risk Assessment ◽  
Reclaimed Water ◽  
Quantitative Microbial Risk Assessment ◽  
Risk Of Infection ◽  
Worst Case ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Risk Assessment Models ◽  
Crop Type ◽  
Annual Risk

ABSTRACT Quantitative microbial risk assessment models for estimating the annual risk of enteric virus infection associated with consuming raw vegetables that have been overhead irrigated with nondisinfected secondary treated reclaimed water were constructed. We ran models for several different scenarios of crop type, viral concentration in effluent, and time since last irrigation event. The mean annual risk of infection was always less for cucumber than for broccoli, cabbage, or lettuce. Across the various crops, effluent qualities, and viral decay rates considered, the annual risk of infection ranged from 10−3 to 10−1 when reclaimed-water irrigation ceased 1 day before harvest and from 10−9 to 10−3 when it ceased 2 weeks before harvest. Two previously published decay coefficients were used to describe the die-off of viruses in the environment. For all combinations of crop type and effluent quality, application of the more aggressive decay coefficient led to annual risks of infection that satisfied the commonly propounded benchmark of ≤10−4, i.e., one infection or less per 10,000 people per year, providing that 14 days had elapsed since irrigation with reclaimed water. Conversely, this benchmark was not attained for any combination of crop and water quality when this withholding period was 1 day. The lower decay rate conferred markedly less protection, with broccoli and cucumber being the only crops satisfying the 10−4 standard for all water qualities after a 14-day withholding period. Sensitivity analyses on the models revealed that in nearly all cases, variation in the amount of produce consumed had the most significant effect on the total uncertainty surrounding the estimate of annual infection risk. The models presented cover what would generally be considered to be worst-case scenarios: overhead irrigation and consumption of vegetables raw. Practices such as subsurface, furrow, or drip irrigation and postharvest washing/disinfection and food preparation could substantially lower risks and need to be considered in future models, particularly for developed nations where these extra risk reduction measures are more common.

Quantitative Microbial Risk Assessment for Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes in Leafy Green Vegetables Consumed at Salad Bars

2010 ◽  
Vol 73 (2) ◽  
pp. 274-285 ◽  
Author(s):  
E. FRANZ ◽  
S. O. TROMP ◽  
H. RIJGERSBERG ◽  
H. J. van der FELS-KLERX
Keyword(s):  
Public Health ◽  
Escherichia Coli ◽  
Risk Assessment ◽  
Monte Carlo ◽  
Escherichia Coli O157 ◽  
Quantitative Microbial Risk Assessment ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
The Public ◽  
E Coli

Fresh vegetables are increasingly recognized as a source of foodborne outbreaks in many parts of the world. The purpose of this study was to conduct a quantitative microbial risk assessment for Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes infection from consumption of leafy green vegetables in salad from salad bars in The Netherlands. Pathogen growth was modeled in Aladin (Agro Logistics Analysis and Design Instrument) using time-temperature profiles in the chilled supply chain and one particular restaurant with a salad bar. A second-order Monte Carlo risk assessment model was constructed (using @Risk) to estimate the public health effects. The temperature in the studied cold chain was well controlled below 5°C. Growth of E. coli O157:H7 and Salmonella was minimal (17 and 15%, respectively). Growth of L. monocytogenes was considerably greater (194%). Based on first-order Monte Carlo simulations, the average number of cases per year in The Netherlands associated the consumption leafy greens in salads from salad bars was 166, 187, and 0.3 for E. coli O157:H7, Salmonella, and L. monocytogenes, respectively. The ranges of the average number of annual cases as estimated by second-order Monte Carlo simulation (with prevalence and number of visitors as uncertain variables) were 42 to 551 for E. coli O157:H7, 81 to 281 for Salmonella, and 0.1 to 0.9 for L. monocytogenes. This study included an integration of modeling pathogen growth in the supply chain of fresh leafy vegetables destined for restaurant salad bars using software designed to model and design logistics and modeling the public health effects using probabilistic risk assessment software.

scholarly journals Human Pathogenic Bacteria Detected in Rainwater: Risk Assessment and Correlation to Microbial Source Tracking Markers and Traditional Indicators

2021 ◽  
Vol 12 ◽  
Author(s):  
Julia K. Denissen ◽  
Brandon Reyneke ◽  
Monique Waso ◽  
Sehaam Khan ◽  
Wesaal Khan
Keyword(s):  
Risk Assessment ◽  
Pathogenic Bacteria ◽  
Microbial Source Tracking ◽  
Source Tracking ◽  
Quantitative Microbial Risk Assessment ◽  
Risk Of Infection ◽  
E Coli ◽  
Human Pathogenic Bacteria ◽  
The Mean ◽  
Annual Risk

Roof-harvested rainwater (RHRW) was investigated for the presence of the human pathogenic bacteria Mycobacterium tuberculosis (M. tuberculosis), Yersinia spp. and Listeria monocytogenes (L. monocytogenes). While Yersinia spp. were detected in 92% (n = 25) of the RHRW samples, and L. monocytogenes and M. tuberculosis were detected in 100% (n = 25) of the samples, a significantly higher mean concentration (1.4 × 103 cells/100 mL) was recorded for L. monocytogenes over the sampling period. As the identification of appropriate water quality indicators is crucial to ensure access to safe water sources, correlation of the pathogens to traditional indicator organisms [Escherichia coli (E. coli) and Enterococcus spp.] and microbial source tracking (MST) markers (Bacteroides HF183, adenovirus and Lachnospiraceae) was conducted. A significant positive correlation was then recorded for E. coli versus L. monocytogenes (r = 0.6738; p = 0.000), and Enterococcus spp. versus the Bacteroides HF183 marker (r = 0.4071; p = 0.043), while a significant negative correlation was observed for M. tuberculosis versus the Bacteroides HF183 marker (r = −0.4558; p = 0.022). Quantitative microbial risk assessment indicated that the mean annual risk of infection posed by L. monocytogenes in the RHRW samples exceeded the annual infection risk benchmark limit (1 × 10–4 infections per person per year) for intentional drinking (∼10–4). In comparison, the mean annual risk of infection posed by E. coli was exceeded for intentional drinking (∼10–1), accidental consumption (∼10–3) and cleaning of the home (∼10–3). However, while the risk posed by M. tuberculosis for the two relevant exposure scenarios [garden hosing (∼10–5) and washing laundry by hand (∼10–5)] was below the benchmark limit, the risk posed by adenovirus for garden hosing (∼10–3) and washing laundry by hand (∼10–3) exceeded the benchmark limit. Thus, while the correlation analysis confirms that traditional indicators and MST markers should be used in combination to accurately monitor the pathogen-associated risk linked to the utilisation of RHRW, the integration of QMRA offers a more site-specific approach to monitor and estimate the human health risks associated with the use of RHRW.

Microbial risk in wastewater irrigated lettuce: comparing Escherichia coli contamination from an experimental site with a laboratory approach

2016 ◽  
Vol 74 (3) ◽  
pp. 749-755 ◽  
Author(s):  
P. Makkaew ◽  
M. Miller ◽  
H. J. Fallowfield ◽  
N. J. Cromar
Keyword(s):  
Escherichia Coli ◽  
Domestic Wastewater ◽  
Quantitative Microbial Risk Assessment ◽  
Experimental Site ◽  
Microbial Risk Assessment ◽  
Plastic Sheet ◽  
Microbial Risk ◽  
E Coli ◽  
Surrogate Method

This study assessed the contamination of Escherichia coli, in lettuce grown with treated domestic wastewater in four different irrigation configurations: open spray, spray under plastic sheet cover, open drip and drip under plastic sheet cover. Samples of lettuce from each irrigation configuration and irrigating wastewater were collected during the growing season. No E. coli was detected in lettuce from drip irrigated beds. All lettuce samples from spray beds were positive for E. coli, however, no statistical difference (p > 0.05) was detected between lettuces grown in open spray or covered spray beds. The results from the field experiment were also compared to a laboratory experiment which used submersion of lettuce in wastewater of known E. coli concentration as a surrogate method to assess contamination following irrigation. The microbial quality of spray bed lettuces was not significantly different from submersed lettuce when irrigated with wastewater containing 1,299.7 E. coli MPN/100 mL (p > 0.05). This study is significant since it is the first to validate that the microbial contamination of lettuce irrigated with wastewater in the field is comparable with a laboratory technique frequently applied in the quantitative microbial risk assessment of the consumption of wastewater irrigated salad crops.

Assessment of E. coli and Salmonella spp. infection risks associated with different fecal sludge disposal practices in Thailand

2009 ◽  
Vol 8 (2) ◽  
pp. 355-364 ◽  
Author(s):  
A. Yajima ◽  
T. Koottatep
Keyword(s):  
High Water ◽  
Developed Countries ◽  
World Health ◽  
Quantitative Microbial Risk Assessment ◽  
Salmonella Spp ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Risk Levels ◽  
E Coli ◽  
Fecal Sludge

The proper management of fecal sludge (FS), to block the transmission pathways of pathogens, is rarely enforced in many parts of the world. Health risks associated with different disposal practices of FS in peri-urban settings of a large metropolis in Thailand were assessed; Tha Klong sub-district with indiscriminate FS dumping, and Klong Luang sub-district which has an FS treatment system. The study showed that indiscriminate FS dumping from along the canal banks and discharge of market waste were likely the major sources of E. coli and Salmonella spp. in contamination of the canal water. The increased microbial pathogen concentrations near the FS treatment facility also indicated contamination risks from poorly designed treatment facilities. Quantitative microbial risk assessment (QMRA) indicated very high water-related infection risk levels compared to the actual locally recorded disease occurrences. These results indicated that the QMRA model needs to be modified to take account of immunological differences between populations in developed countries, where the model was developed, and developing countries. In addition, further sensitivity factors are needed to reflect different societal behavior patterns, and therefore contact with potentially contaminated water, in different sub-populations of many less developed communities.

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