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.

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.

A review of quantitative microbial risk assessment in the management of Escherichia coli O157:H7 on beef

Meat Science ◽  
2006 ◽  
Vol 74 (1) ◽  
pp. 76-88 ◽  
Author(s):  
Geraldine Duffy ◽  
Enda Cummins ◽  
Pádraig Nally ◽  
Stephen O’ Brien ◽  
Francis Butler
Keyword(s):  
Escherichia Coli ◽  
Risk Assessment ◽  
Escherichia Coli O157 ◽  
Quantitative Microbial Risk Assessment ◽  
Microbial Risk Assessment ◽  
Microbial Risk

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.

scholarly journals Evaluation of a Disinfectant Wipe Intervention on Fomite-to-Finger Microbial Transfer

2014 ◽  
Vol 80 (10) ◽  
pp. 3113-3118 ◽  
Author(s):  
Gerardo U. Lopez ◽  
Masaaki Kitajima ◽  
Aaron Havas ◽  
Charles P. Gerba ◽  
Kelly A. Reynolds
Keyword(s):  
Escherichia Coli ◽  
Respiratory Pathogens ◽  
Quantitative Microbial Risk Assessment ◽  
Content Type ◽  
Microbial Risk Assessment ◽  
Surface Disinfection ◽  
Microbial Risk ◽  
Risk Assessment Models ◽  
The Mean ◽  
The Impact

ABSTRACTInanimate surfaces, or fomites, can serve as routes of transmission of enteric and respiratory pathogens. No previous studies have evaluated the impact of surface disinfection on the level of pathogen transfer from fomites to fingers. Thus, the present study investigated the change in microbial transfer from contaminated fomites to fingers following disinfecting wipe use.Escherichia coli(108to 109CFU/ml),Staphylococcus aureus(109CFU/ml),Bacillus thuringiensisspores (107to 108CFU/ml), and poliovirus 1 (108PFU/ml) were seeded on ceramic tile, laminate, and granite in 10-μl drops and allowed to dry for 30 min at a relative humidity of 15 to 32%. The seeded fomites were treated with a disinfectant wipe and allowed to dry for an additional 10 min. Fomite-to-finger transfer trials were conducted to measure concentrations of transferred microorganisms on the fingers after the disinfectant wipe intervention. The mean log10reduction of the test microorganisms on fomites by the disinfectant wipe treatment varied from 1.9 to 5.0, depending on the microorganism and the fomite. Microbial transfer from disinfectant-wipe-treated fomites was lower (up to <0.1% on average) than from nontreated surfaces (up to 36.3% on average, reported in our previous study) for all types of microorganisms and fomites. This is the first study quantifying microbial transfer from contaminated fomites to fingers after the use of disinfectant wipe intervention. The data generated in the present study can be used in quantitative microbial risk assessment models to predict the effect of disinfectant wipes in reducing microbial exposure.

Quantitative Assessment of the Microbial Risk of Leafy Greens from Farm to Consumption: Preliminary Framework, Data, and Risk Estimates

2011 ◽  
Vol 74 (5) ◽  
pp. 700-708 ◽  
Author(s):  
MICHELLE D. DANYLUK ◽  
DONALD W. SCHAFFNER
Keyword(s):  
Risk Assessment ◽  
Risk Model ◽  
Assessment Model ◽  
Quantitative Microbial Risk Assessment ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
E Coli ◽  
Leafy Greens ◽  
Risk Estimates ◽  
Washing Process

This project was undertaken to relate what is known about the behavior of Escherichia coli O157:H7 under laboratory conditions and integrate this information to what is known regarding the 2006 E. coli O157:H7 spinach outbreak in the context of a quantitative microbial risk assessment. The risk model explicitly assumes that all contamination arises from exposure in the field. Extracted data, models, and user inputs were entered into an Excel spreadsheet, and the modeling software @RISK was used to perform Monte Carlo simulations. The model predicts that cut leafy greens that are temperature abused will support the growth of E. coli O157:H7, and populations of the organism may increase by as much a 1 log CFU/day under optimal temperature conditions. When the risk model used a starting level of −1 log CFU/g, with 0.1% of incoming servings contaminated, the predicted numbers of cells per serving were within the range of best available estimates of pathogen levels during the outbreak. The model predicts that levels in the field of −1 log CFU/g and 0.1% prevalence could have resulted in an outbreak approximately the size of the 2006 E. coli O157:H7 outbreak. This quantitative microbial risk assessment model represents a preliminary framework that identifies available data and provides initial risk estimates for pathogenic E. coli in leafy greens. Data gaps include retail storage times, correlations between storage time and temperature, determining the importance of E. coli O157:H7 in leafy greens lag time models, and validation of the importance of cross-contamination during the washing process.

scholarly journals Quantitative microbial risk assessment related to urban wastewater and lagoon water reuse in Abidjan, Côte d'Ivoire

2013 ◽  
Vol 12 (2) ◽  
pp. 301-309 ◽  
Author(s):  
R. I. Yapo ◽  
B. Koné ◽  
B. Bonfoh ◽  
G. Cissé ◽  
J. Zinsstag ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Cote D'ivoire ◽  
Côte D’Ivoire ◽  
Quantitative Microbial Risk Assessment ◽  
Urban Wastewater ◽  
Cote D’Ivoire ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
E Coli ◽  
Lagoon Water

We assessed the infection risks related to the use of wastewater in Abidjan, Côte d'Ivoire, by using quantitative microbial risk assessment (QMRA). Giardia lamblia and Escherichia coli were isolated and identified in wastewater samples from the canal and lagoon. The exposure assessment was conducted using a cross-sectional survey by questionnaire with 150 individuals who were in contact with the wastewater during their daily activities of swimming, fishing, washing, and collecting materials for reuse. Risk was characterised using the Monte Carlo simulation with 10,000 iterations. Results showed high contamination of water by G. lamblia and E. coli (12.8 CFU/100 mL to 2.97 × 104CFU/100 mL and from 0 cyst/L to 18.5 cysts/L, respectively). Estimates of yearly average infection risks for E. coli (90.07–99.90%, assuming that 8% of E. coli were E. coli O157:H7) and G. lamblia (9.4–34.78%) were much higher than the acceptable risk (10−4). These results suggest the need for wastewater treatment plants, raising awareness in the population in contact with urban wastewater and lagoon water. Our study also showed that QMRA is appropriate to study health risks in settings with limited data and budget resources.

Microbiological Risk from Minimally Processed Packaged Salads in the Dutch Food Chain

2014 ◽  
Vol 77 (3) ◽  
pp. 395-403 ◽  
Author(s):  
ANNEMARIE PIELAAT ◽  
FRANS M. van LEUSDEN ◽  
LUCAS M. WIJNANDS
Keyword(s):  
Risk Assessment ◽  
Quantitative Microbial Risk Assessment ◽  
Concentration Data ◽  
Production Chain ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
E Coli ◽  
Human Illness ◽  
Campylobacter Spp ◽  
Microbiological Surveillance

The objective of this study was to evaluate the microbial hazard associated with the consumption of mixed salads produced under standard conditions. The presence of Salmonella, Campylobacter spp., and Escherichia coli O157 in the Dutch production chain of mixed salads was determined. Microbial prevalence and concentration data from a microbiological surveillance study were used as inputs for the quantitative microbial risk assessment. Chain logistics, production figures, and consumption patterns were combined with the survey data for the risk assessment chain approach. The results of the sample analysis were used to track events from contamination through human illness. Wide 95% confidence intervals around the mean were found for estimated annual numbers of illnesses resulting from the consumption of mixed salads contaminated with Salmonella Typhimurium DT104 (0 to 10,300 cases), Campylobacter spp. (0 to 92,000 cases), or E. coli (0 to 800 cases). The main sources of uncertainty are the lack of decontamination data (i.e., produce washing during processing) and an appropriate dose-response relationship.

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