Mathematical Modeling and Assessment of Microbial Migration during the Sprouting of Alfalfa in Trays in a Nonuniformly Contaminated Seed Batch Using Enterobacter aerogenes as a Surrogate for Salmonella Stanley

2007 ◽  
Vol 70 (11) ◽  
pp. 2602-2605 ◽  
Author(s):  
BIN LIU ◽  
DONALD W. SCHAFFNER
Keyword(s):  
Irrigation Water ◽  
Membrane Filtration ◽  
Microbial Contamination ◽  
Food Poisoning ◽  
Enterobacter Aerogenes ◽  
Probability Of Detection ◽  
Microbial Populations ◽  
Water Sampling ◽  
The Past ◽  
Low Concentrations

Raw seed sprouts have been implicated in several food poisoning outbreaks in the past 10 years. The U.S. Food and Drug Administration recommends that sprout growers use interventions (such as testing of spent irrigation water) to control the presence of pathogens in the finished product. During the sprouting process, initially low concentrations of pathogen may increase, and contamination may spread within a batch of sprouting seeds. A model of pathogen growth as a function of time and distance from the contamination spot during the sprouting of alfalfa in trays has been developed with Enterobacter aerogenes. The probability of detecting contamination was assessed by logistic regression at various time points and distances by sampling from sprouts or irrigation water. Our results demonstrate that microbial populations and possibility of detection were greatly reduced at distances of ≥20 cm from the point of contamination in a seed batch during tray sprouting; however, the probability of detecting microbial contamination at distances less than 10 cm from the point of inoculation was almost 100% at the end of the sprouting process. Our results also show that sampling irrigation water, especially large volumes of water, is highly effective at detecting contamination: by collecting 100 ml of irrigation water for membrane filtration, the probability of detection was increased by three to four times during the first6hof seed germination. Our findings have quantified the degree to which a small level of contamination will spread throughout a tray of sprouting alfalfa seeds and subsequently be detected by either sprout or irrigation water sampling.

Quantitative Analysis of the Growth of Salmonella Stanley during Alfalfa Sprouting and Evaluation of Enterobacter aerogenes as Its Surrogate

2007 ◽  
Vol 70 (2) ◽  
pp. 316-322 ◽  
Author(s):  
BIN LIU ◽  
DONALD W. SCHAFFNER
Keyword(s):  
Nalidixic Acid ◽  
Growth Rates ◽  
Irrigation Water ◽  
Large Scale ◽  
Food Poisoning ◽  
Enterobacter Aerogenes ◽  
Process Data ◽  
Inoculum Concentration ◽  
Logistic Regression Models ◽  
Water Testing

Raw seed sprouts have been implicated in several food poisoning outbreaks in the last 10 years. Few studies have included investigations of factors influencing the effectiveness of testing spent irrigation water, and in no studies to date has a nonpathogenic surrogate been identified as suitable for large-scale irrigation water testing trials. Alfalfa seeds were inoculated with Salmonella Stanley or its presumptive surrogate (nalidixic acid–resistant Enterobacter aerogenes) at three concentrations (∼3, ∼30, and ∼300 CFU/g) and were then transferred into either flasks or a bench top–scale sprouting chamber. Microbial concentrations were determined in seeds, sprouts, and irrigation water at various times during a 4-day sprouting process. Data were fit to logistic regression models, and growth rates and maximum concentrations were compared using the generalized linear model procedure of SAS. No significant differences in growth rates were observed among samples taken from flasks or the chamber. Microbial concentrations in irrigation water were not significantly different from concentrations in sprout samples obtained at the same time. E. aerogenes concentrations were similar to those of Salmonella Stanley at corresponding time points for all three inoculum concentrations. Growth rates were also constant regardless of inoculum concentration or strain, except that lower inoculum concentrations resulted in lower final concentrations proportional to their initial concentrations. This research demonstrated that a nonpathogenic easy-to-isolate surrogate (nalidixic acid–resistant E. aerogenes) provides results similar to those obtained with Salmonella Stanley, supporting the use of this surrogate in future large-scale experiments.

A Year in the Life of a Contaminated Heater-Cooler Unit With Mycobacterium chimaera?

2017 ◽  
Vol 38 (06) ◽  
pp. 705-711 ◽  
Author(s):  
Mark I. Garvey ◽  
Craig W. Bradley ◽  
Jimmy Walker
Keyword(s):  
United Kingdom ◽  
Water Samples ◽  
Membrane Filtration ◽  
Microbial Load ◽  
Water Sampling ◽  
University Hospitals ◽  
The Past ◽  
The United Kingdom ◽  
Wide Range ◽  
Number Of Microorganisms

OBJECTIVE Heater-cooler units (HCUs) have been shown to be a source of Mycobacterium chimaera infections. For the past year, weekly water samples have been taken from HCUs used at University Hospitals Birmingham (UHB) NHS Foundation Trust. We report the microbial contamination of the HCUs over a year detailing the decontamination regimes applied at UHB to reduce the microbial load. DESIGN Observational study SETTING UHB is a tertiary referral teaching hospital in Birmingham, United Kingdom, that provides clinical services to nearly 1 million patients every year. The UHB Cardiac department is one of the largest in the United Kingdom and provides treatment for adult patients with a wide range of cardiac diseases. METHODS Water samples taken from HCUs used at UHB for cardiopulmonary bypass surgery were sampled over a year to determine the number of microorganisms by membrane filtration. Various decontamination processes were employed throughout the year. RESULTS Varying total viable counts containing a wide variety of microorganisms were obtained from water inside the HCUs. No M. chimaera were isolated after replacement of the HCU internal tubing. Stringent decontamination regimes resulted in degradation of the HCUs and increased TVCs after several months. CONCLUSION More work is required to ensure effective decontamination processes to reduce the microbial load within the HCUs. Our studies indicate that weekly water sampling for TVC will be required indefinitely to monitor the water quality in these units as well as regular replacement of the tubing to control the build-up of biofilm. Infect Control Hosp Epidemiol 2017;38:705–711

scholarly journals Membrane Fouling Controlled by Adjustment of Biological Treatment Parameters in Step-Aerating MBR

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 553
Author(s):  
Dimitra C. Banti ◽  
Manassis Mitrakas ◽  
Petros Samaras
Keyword(s):  
Membrane Fouling ◽  
Membrane Filtration ◽  
Municipal Wastewater ◽  
Operating Conditions ◽  
Transmembrane Pressure ◽  
Aeration Tank ◽  
Filamentous Bacteria ◽  
Membrane Performance ◽  
Low Concentrations ◽  
Fouling Reduction

A promising solution for membrane fouling reduction in membrane bioreactors (MBRs) could be the adjustment of operating parameters of the MBR, such as hydraulic retention time (HRT), food/microorganisms (F/M) loading and dissolved oxygen (DO) concentration, aiming to modify the sludge morphology to the direction of improvement of the membrane filtration. In this work, these parameters were investigated in a step-aerating pilot MBR that treated municipal wastewater, in order to control the filamentous population. When F/M loading in the first aeration tank (AT1) was ≤0.65 ± 0.2 g COD/g MLSS/d at 20 ± 3 °C, DO = 2.5 ± 0.1 mg/L and HRT = 1.6 h, the filamentous bacteria were controlled effectively at a moderate filament index of 1.5–3. The moderate population of filamentous bacteria improved the membrane performance, leading to low transmembrane pressure (TMP) at values ≤2 kPa for a great period, while at the control MBR the TMP gradually increased reaching 14 kPa. Soluble microbial products (SMP), were also maintained at low concentrations, contributing additionally to the reduction of ΤΜP. Finally, the step-aerating MBR process and the selected imposed operating conditions of HRT, F/M and DO improved the MBR performance in terms of fouling control, facilitating its future wider application.

scholarly journals Update on Bolognese surgeon Dr. Benedetto Schiassi: the importance of Schiassi’s tentorium

2017 ◽  
Author(s):  
Sergio Sabbatani ◽  
Luca Ansaloni ◽  
Massimo Sartelli ◽  
Federico Coccolini ◽  
Salomone Di Saverio ◽  
...  
Keyword(s):  
20Th Century ◽  
19Th Century ◽  
Microbial Contamination ◽  
Scientific Activity ◽  
Risk Of Infection ◽  
Noticeable Increase ◽  
The Past ◽  
Relevant Today ◽  
The 19Th Century

Risk of infection remains a major concern for surgeons. The expansion of surgery towards the end of the 19th century determined a noticeable increase in septicemia and gangrene, and surgeons developed various techniques to limit them. In a previous publication, we reminded our readers of one of the gems of Italian surgery, Dr. Giuseppe Ruggi, who operated in Bologna from the end of 19th to the beginning of the 20th century. To him we owe the introduction and dissemination of the antiseptic method in Bologna. His scientific activity continued with Dr. Benedetto Schiassi, his successor. The techniques used to avoid microbial contamination by the Italian surgeon Dr. Schiassi, are particularly interesting, as Schiassi’s tentorium is still useful. Despite advances in surgical technologies, many innovations to prevent infection in surgery proposed in the past are still relevant today.

Phosphorus removal with membrane filtration for surface water treatment

2002 ◽  
Vol 46 (4-5) ◽  
pp. 257-264 ◽  
Author(s):  
A. Dietze ◽  
R. Gnirß ◽  
U. Wiesmann
Keyword(s):  
Surface Water ◽  
Ground Water ◽  
Membrane Filtration ◽  
Current Treatment ◽  
Particulate Phosphorus ◽  
Surface Water Treatment ◽  
Low Concentrations ◽  
Drinking Water Production ◽  
Quality Water ◽  
High Degree

Surface waters are often burdened with inflows of low quality water, so that drinking-water production, swimming or ground water charging must be restricted. To ensure the long-term use of such surface water it is necessary to treat the influents or the water used for ground water charging. The current treatment process for phosphorus and turbidity removal is a process combination called floc filtration. By using this conventional method it is possible to reduce the dissolved ortho-phosphate and the turbidity (particulate phosphorus) as well as the amounts of algae and pathogenic organisms to very low concentrations. The high degree of reduction is only achieved by a relatively high dosage of chemicals. A comparison will be made between this process, which represents the state-of-the-art, and the combination of precipitation/coagulation with micro-/ultrafiltration in dead-end filtration mode.

Removal of color substances using photocatalytic oxidation for membrane filtration processes

2001 ◽  
Vol 43 (10) ◽  
pp. 319-325 ◽  
Author(s):  
J. H. Tay ◽  
D. Chen ◽  
D. D. Sun
Keyword(s):  
Hydrogen Peroxide ◽  
Membrane Filtration ◽  
Photocatalytic Oxidation ◽  
Removal Rate ◽  
Membrane Surface ◽  
Rejection Rate ◽  
Solution Treated ◽  
Low Concentrations ◽  
Photo Catalytic Oxidation ◽  
Positive Effect

This study aims to remove the color substances, which normally cause difficulties in membrane filtration processes due to fouling using heterogeneous UV/TiO2/H2O2 reactor. It is confirmed that the technique used in this study was effective to remove TOC at 38% and color400 at 89% within 150-min irradiation. The experiment results showed that low concentrations of hydrogen peroxide dosage (less than 0.016 M) to UV/TiO2 system accelerated the TOC and Color400 removal rate from 9% to 38% and 40% to 89% respectively, while over-dosage made this positive effect decline. The humic acid solution treated by photo catalytic oxidation in UV/TiO2/H2O2 reactor did not change the zeta potential on membrane surface and membrane rejection rate.

Food Safety: Problems of the Past and Perspectives of the Future1

1982 ◽  
Vol 45 (7) ◽  
pp. 658-660 ◽  
Author(s):  
E. M. FOSTER
Keyword(s):  
United States ◽  
Food Poisoning ◽  
Food Service ◽  
The United States ◽  
Red Tides ◽  
Animal Products ◽  
The Past ◽  
Processing Plants ◽  
Market Areas ◽  
Bacterial Food

Historically, most bacterial food poisoning in the United States is associated with mishandling, either in the home or in the food service establishment. Outbreaks traceable to errors in processing plants are rare. When they do occur they are often associated with changes in processing or packaging technology whose effect is not determined before the product is on the market. Areas of future concern that need research include (1) a better understanding of the mycotoxins; (2) how to minimize Salmonella contamination in animal products; (3) how to prevent, or at least predict, red tides; (4) better bactericidal agents that can be applied to foods; (5) an understanding of the nature and significance of mutagenic agents that are produced in foods during cooking.

scholarly journals Experiments on Staphylococcus food poisoning

1938 ◽  
Vol 38 (5) ◽  
pp. 623-637 ◽  
Author(s):  
F. C. Minett
Keyword(s):  
Culture Medium ◽  
Food Poisoning ◽  
Oral Route ◽  
Natural Conditions ◽  
Staph Aureus ◽  
Layer Cake ◽  
Feeding Experiments ◽  
Low Concentrations ◽  
C 30 ◽  
Variable Susceptibility

1. Feeding tests on monkeys (Macacus rhesus), dogs and cats are unsatisfactory for detecting the presence of enterotoxin, owing to the variable susceptibility of these animals by the oral route.2. Using Dolman's method, in which the material is injected intra-peritoneally into kittens, the production of enterotoxin has been demonstrated by: (a) sixteen out of thirty-eight strains of Staph. aureus, isolated from cases of acute or chronic mastitis or from normal udder milk; (b) four out of five strains of Bact. coli, mostly from calves with “white scours”. No enterotoxin was obtained from fifteen strains of Str. agalactiae from mastitis in cows.3. The formation of enterotoxin under natural conditions has been observed: (a) In udder milk seeded with Staph. aureus or naturally contaminated with that organism and stored at atmospheric temperatures (18 and 22°C.). The substance remains active in cheese prepared from such milk. (b) In layer cake made with cream naturally contaminated with Staph. aureus.4. A small outbreak of poisoning due to potted meat paste was shown to be caused by a non-haemolytic Staphylococcus.5. A few feeding experiments on man with milk or cream, in which food-poisoning staphylococci had grown, were negative, but on one occasion a Staphylococcus from a case of mastitis yielded a culture filtrate which caused symptoms of food poisoning.6. Enterotoxin has the following properties. It is resistant to heat (95°C., 30 min.), to low concentrations of formalin sufficient to destroy the haemolytic toxin, to acid (pH 5·0), and to rennet, but is destroyed by trypsin.It diffuses freely into the culture medium but only slightly through collodion. It is antigenic. Its properties are such that enterotoxin can be classed as a bacterial exotoxin.

scholarly journals Elevated and variable groundwater iron in rural northwestern Bangladesh

2010 ◽  
Vol 8 (4) ◽  
pp. 818-825 ◽  
Author(s):  
Rebecca D. Merrill ◽  
Alain B. Labrique ◽  
Abu Ahmed Shamim ◽  
Kerry Schulze ◽  
Parul Christian ◽  
...  
Keyword(s):  
Rural Communities ◽  
Mineral Content ◽  
Iron Concentration ◽  
Water Source ◽  
Water Sampling ◽  
The Past ◽  
Variation Range ◽  
Northwestern Bangladesh ◽  
Health Relevance ◽  
Few Data

Over the past 30 years, tubewells have become a ubiquitous source of potable groundwater in South Asia. Considered safer than surface water, groundwater naturally contains minerals that may impact human health; however, few data exist on tubewell water mineral content or its association with human nutritional or health conditions. We surveyed iron concentration in tubewell water across a 435 km2, contiguous, rural area in northwestern Bangladesh to map and quantify levels of iron in drinking water. One tubewell was randomly sampled from each of 948 adjacent grid cells 675 m2 in size. Water sampling was standardized and iron concentration measured using a field-based colorimetric kit. The median (interquartile range) concentration of iron in tubewell water was 7.6 (1.6, 17.6) mg l−1. There was high geographic variation (range of 0–46.5 mg l−1), and iron in only 3% of surveyed tubewells fell below the WHO aesthetic cut-off of 0.3 mg l−1 suggesting elevated levels of iron throughout the area. Villagers accurately perceived groundwater iron concentration, based on a 4-point (‘none’, ‘a little’, ‘medium’, ‘a lot’) scale (p<0.001). Water source iron content can be readily quantified in population settings offering the potential to evaluate the health relevance of groundwater iron exposure in rural communities.

Effect of fluorinated saline water on oats

1986 ◽  
Vol 106 (2) ◽  
pp. 429-431
Author(s):  
R. P. S. Chauhan ◽  
C. P. S. Chauhan
Keyword(s):  
Irrigation Water ◽  
Saline Water ◽  
Poor Quality ◽  
Contaminated Water ◽  
Soluble Salts ◽  
Wheat Seedlings ◽  
Tissue Content ◽  
Low Concentrations ◽  
Germination And Growth ◽  
Arid And Semiarid

Poor quality underground irrigation water occurs in most arid and semiarid regions. This water contains not only excessive amounts of soluble salts but also fluoride (F) from traces to 30 mg/1 in India, but usually the concentration of F is below 5 mg/1 (Gupta, 1979). The effect of F on plants is not well known but plants accumulate it when it is present in the soil or applied through irrigation water. Singh, Chhabra & Abrol (1980) found that soil-applied F at 50 mg/kg was toxic to rice and 32 mg/kg tissue content of F was toxic to wheat. Paliwal (1972) found that F content in berseem increased from 18·1 to 52·7 mg/kg when the crop was irrigated with F contaminated water. He further found that 10 mg F/kg inhibited germination and growth of wheat seedlings, and whilst low concentrations of F may not be toxic to plants they may be hazardous to animals continuously fed on fodders containing fluoride.The effect of fluoride-rich saline water on the yield and F content of fodder oats has therefore been determined.

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