Detection Of Total Coliforms Research Articles

Physical-chemical and microbiological characterization of water destined to hemodialysis

This research evaluated the physical-chemical and microbiological parameters of water and dialysate in four distinct hemodialysis units located in the southeast region of Brazil. The physical-chemical parameters evaluated were pH, electric conductivity, turbidity, alkalinity, free chlorine, nitrate, fluoride, chloride, sulfate, sodium, potassium, calcium, and magnesium ion concentrations. Microcystin was also quantified. The microbiological parameters evaluated were the detection of total coliform, total heterotrophic bacteria count (THB), and the isolation and identification of microorganisms in pre-reverse osmosis treatment and post-reverse osmosis treatment water samples and dialysate. The nitrate, fluoride and THB levels found in the water samples may present risk to the patient under hemodialysis treatment. Microcystin was detected in one of the potable water samples. Microorganisms were identified throughout the hemodialysis of the entire water treatment system, with Ralstonia sp. being the most frequent. The presence of emergent pathogenic bacteria highlighted in this study highlights the necessity of microbiological monitoring of water destined for hemodialysis. Keywords: dialysate, hemodialysis, water treatment.

Assessment of Drinking Water Quality from Source to Household Storage Containers in Kachisi town, West Shewa, Ethiopia

A wide range of human and natural processes affect the quality of fresh waters and diseases related to contamination of drinking water constitute a major burden on human health. Thus, this study was conducted to assess the quality of drinking water supplied to Kachisi town using selected physicochemical and bacteriological parameters. A total of 60 water samples in triplicate were collected from boreholes, water reservoirs, household taps and storage containers in the households between October, 2019 and February, 2020. The physiochemical parameters were measured using HACH HQ440d multi meter and portable digital spectrophotometer (DR/6000) according to HACH instruction and bacteriological parameters were analyzed using the membrane filtration technique. The study results indicated that temperature and pH of the water samples were in the range of 18.77 0C and 21.4 0C, and 7.05 and 7.73, respectively. Total dissolved solids fell between 93 mg/l and116 mg/l while electrical conductivity records ranged between 185µS/cm and 232 µS/cm. The concentrations of Iron, nitrate and phosphate were in the range between 0.01-0.26 mg/l, 2.20-5.72 mg/l and 0.12-0.76 mg/l, respectively. Total Coliforms loadalso varied from 1CFU/100ml to 2CFU/100ml in samples collected from boreholes and reservoirs, from 1CFU/100ml to 12CFU/100ml in tap water samples and from 6CFU/100ml to 22CFU/100ml in samples from storage containers in the households. Fecal Coliform was negative in the water samples collected from boreholes, reservoirs and household taps while it was detected in 25% of the samples collected from household storage containers in the rangeof 3CFU/100ml to 5CFU/100ml. The detection of Total Coliforms in all water samples and Faecal Coliforms in some of the household containers samples might be attributed to absence of disinfection, lack of regular supervision of the system, poor water management and lack of safe water storage and handling practices.

Classification of water by bacterial presence using chemometrics associated with excitation-emission matrix fluorescence spectroscopy

Bacterial presence in water is an important indicator of water quality and, when found in high concentrations, may risk human health. The detection of total coliforms, thermotolerant coliforms, and Escherichia coli (E. coli) in water through standard methods involves time-consuming and expensive laboratory tests, which may not always provide timely and accurate results. An alternative approach is excitation-emission matrix fluorescence spectroscopy (EEMFS), which offers fast detection of bacteria in water by analyzing fluorescent compounds. Chemometrics methods can be used to process EEMF spectrum, extract the relevant information, and differentiate water samples based on the presence of bacteria using classification models. In this study, various classification algorithms were applied to EEMFS datasets, including k-nearest neighbors (k-NN), partial least squares discriminant analysis (PLS-DA), multiway-PLS (NPLS-DA), principal component analysis with discriminant analysis (PCA-DA), support vector machines (SVM), and random forest (RF). Models were developed after the unfold multiway and parallel factor analysis (PARAFAC) to classify groundwater, freshwater, saltwater, and treated water samples according to the presence of E. coli, thermotolerant coliforms, and total coliforms. Among these models, PLS-DA, SVM, and RF demonstrated superior performance in discriminating the samples in most cases. In the test sets, the accuracy of the best models for total coliforms varied from 85.2% to 100% for groundwater, 71.4% to 98.2% for freshwater, 64.6% to 81.3% for treated water, and 65.8% to 71.1% for saltwater. Accuracy for E. coli and thermotolerant coliforms ranged from 89.3% to 100% in groundwater and from 64.7% to 87.5% for treated water. Results for thermotolerant coliforms in freshwater were 64.8% to 95.2%, and 63.3% to 76.7% for saltwater. For E. coli, accuracy ranged from 73.8% to 78.6% for freshwater and 65.0% to 80.0% for saltwater.

Novel primer designing and PCR-AFLP approach for an expeditious detection of coliforms in potable waters

Molecular techniques involving 16S rRNA gene have long been proved to be a mainstay of sequence-based bacterial analysis and enhance the competence of bacterial removal in drinking water and food. The main goal of this analysis was to reduce the time of detection of total coliforms by developing 16S rRNA based DNA markers by targeting variable region in the 16S rRNA gene position of V2 and V9. Coliform specific primers (189F and 1447R) were designed to amplify total coliform with an amplicon size of 1300 bp. The PCR product was later digested with Hind III and BseRI (restriction enzymes) to differentiate the type of contamination caused by fecal and non-fecal coliforms respectively. The digested amplicons were run on agarose gel electrophoresis and contamination levels were estimated based on the respective band pattern. This method can be applicable to know the coliform contamination levels of potable waters, in food and beverage industries within a short period of time. To our knowledge, this is the first report on newly designed primers which not only amplify coliform bacteria, followed by various restriction digestions of these amplicons but also provides unique band patterns to identify coliforms at genus level.

Development of total coliform detection kit using body temperature

Technological advances have increased access to clean water, but 3.4 million people around the world die from waterborne disease every year. Currently, there is equipment capable of detecting pathogens that cause waterborne disease, but access to detection equipment is limited in areas where power supply to use detection equipment is unavailable or where standard detection equipment is too expensive to purchase. In this paper, we will deal with the total coliform detection kit using body temperature that can be used in areas suffering from above difficulties. ColiQuant, total coliform detection kit using body temperature, is a method of putting sample water in a tube containing a substrate that shows a color reaction by an enzyme, culturing the total coliform using body temperature, and determining the presence of the total coliform through color change. In addition, it is possible to detect the total coliform at a lower price (3,000 won/$3) than existing equipment of millions of won or more, so it can be used easily in developing and underdeveloped countries. This paper introduces the research and development process of the total coliform detection kit using body temperature and present the social value of the ColiQuant.

Microbiological evaluation of Vietnamese Pho ingredients in Toronto

Introduction: Beef and bean sprouts have often been implicated in foodborne illness (FBI) outbreaks. The traditional Vietnamese dish, Pho, uses both as its main ingredients and, therefore, presents significant concerns from a food safety perspective. The present study investigated food safety concerns associated with Pho through the detection of total coliform and Escherichia coli. Methods: Thirty-two Vietnamese restaurants in Toronto, Ontario, Canada, were selected for the study based on inclusion criteria. All restaurant operators were briefed prior to sampling and were informed that their consent and participation were voluntary. Fourteen restaurants consented to providing samples and allowing their broth temperatures to be taken. Three types of samples were obtained from each location: raw beef (RB), cooked beef (CB), and bean sprouts (BS). All samples were couriered to an accredited laboratory for microbiological analysis via 3M petrifilm E. coli/coliform count plates. Based on reported total coliform count (TCC), locations were segmented into low, medium, and high contamination categories. Subsequent correlational analysis were conducted based on lab detection data to identify potential links between E. coli count (ECC) and TCC, TCC and broth temperature, and ECC and broth temperature. In addition, an ANOVA was performed to examine for differences in TCC by sample types, differences in TCC by suppliers, differences in ECC by sample types, differences in ECC by suppliers, and differences in TCC by location types. Results: ANOVA indicated a significant effect of sample type on TCC for all three different sample types, with post hoc comparisons elucidating significantly lower TCC in CB and RB samples, compared with BS samples. Subsequent analysis further indicated the significant effect of location category on TCC, with post hoc comparisons demonstrating significantly higher TCC in Category 3 locations compared to Category 1 and 2 locations. All other analysis yielded nonstatistically significant results. Conclusion: This study presented significant findings in linking Pho ingredients to potential food safety concerns. Specifically, temperature control was identified as a possible cause for high TCC and E. coli detection at select restaurants. Although analysis involving E. coli did not yield any significant results, any E. coli found on ready-to-eat food at a restaurant is problematic from a food safety perspective. Based on the results, we recommended policy changes to incentivize restaurants to maintain high hygienic standards and improve efficiency of the public health inspection process.

Differentiating Sources of Fecal Contamination to Wilderness Waters Using Droplet Digital PCR and Fecal Indicator Bacteria Methods.

Human activity in wilderness areas has the potential to affect aquatic ecosystems, including through the introduction of microorganisms associated with fecal contamination. We examined fecal microorganism contamination in water sources (lake outlets, snowmelt streams) in the popular Absaroka Beartooth Wilderness in the United States. Although the region is remote, increasing human visitation has the potential to negatively affect water quality, with particular concern about human-derived microorganism fecal contaminants. We used standard fecal indicator bacterial assays that quantified total coliform bacteria and Escherichia coli concentrations, together with more specific polymerase chain reaction-based microbial assays that identified possible human sources of fecal microorganisms in these waters. Total coliforms were detected at all lake outlets (21 of 21 sites), and E coli was detected at 11 of 21 sites. Droplet digital polymerase chain reaction assays revealed the presence of human feces-derived microorganisms, albeit at abundances below the limit of detection (<10 gene copies per milliliter of water) at all but 1 of the sampling sites. Our results suggest low prevalence of water-borne pathogens (specifically E coli and human-derived Bacteroides) in this popular wilderness area. However, widespread detection of total coliforms, Bacteroides, and E coli highlight the importance of purifying water sources in wilderness areas before consumption. Specific sources of total coliforms and E coli in these waters remain unknown but could derive from wild or domesticated animals that inhabit or visit the Absaroka Beartooth Wilderness. Hence, although contamination by human fecal microorganisms appears minimal, human visitation could indirectly influence fecal contamination through domesticated animals.

Venta a granel de embutidos: una tendencia de comercialización asociada al riesgo de enfermedades trasmitidas por alimentos en Culiacán, México

La naturaleza, producción y consumo de los embutidos definen al alimento como vulnerable, a la contaminación con microorganismos patógenos que propicien enfermedades transmitidas por los alimentos. El objetivo del estudio fue evaluar la influencia de la venta a granel de embutidos, sobre la calidad higienica y la prevalencia de L. monocytogenes y Salmonella. Para ello, se recolectaron 96 muestras de embutidos (salchicha y jamón) de 15 marcas nacionales, y se clasificaron equitativamente por tipo de venta; paquete original (n= 48) y granel (n= 48). La detección de coliformes totales, Escherichia coli, Salmonella, y L. monocytogenes se analizó mediante cultivo tradicional. El 42.7 % (41/96) de las muestras de embutidos estuvieron fuera de especificación sanitaria en términos de coliformes totales y E. coli. El análisis estadístico mostró que el tipo de venta es un indicador del riesgo microbiano en embutidos (χ2=40.0, P=0.000), ya que el número de muestras con deficiente calidad higiénica fue mayor para la venta a granel (69.0 %) comparada con las que se venden en paquete (17.0 %). Adicionalmente, el análisis de riesgo mostró que la venta a granel incrementa 41.8 y 5.9 veces el riesgo de adquirir jamón y salchichas de mala calidad microbiológica (P&lt;0.05), respectivamente. Mientras que, el tipo de venta no influenció la presencia de L. monocytogenes (6.3 %) en las muestras. Se recomienda a los consumidores evitar la compra a granel de los embutidos; y los productores y vendedores deben reforzar las buenas prácticas higiénicas que permitirán asegurar la inocuidad, y minimizar el riesgo de infecciones.

Microbiological quality of water sources in the West region of Cameroon: quantitative detection of total coliforms using Micro Biological Survey method

BackgroundAdequate supply of safe drinking-water remains a critical issue in most developing countries. The whole western region of Cameroon doesn’t have a sustainable continuous water supply system, which leads most people to use potentially contaminated water sources to meet their daily water needs. Previous, studies carried out in similar areas of Cameroon have highlighted the poor bacteriological quality of water sources used as drinking-water by the local populations.MethodsThis study used the Micro Biological Survey method, a rapid colorimetric test for the quantitative detection of Coliforms in water samples. 22 water sources (12 improved and 10 unimproved) were identified; 1 water sample of 50 ml was collected in sterile plastic tubes, immediately kept in a refrigerator box and transported to the laboratory for analysis. 1 ml of each sample was inoculated in the Coliforms Micro Biological Survey (Coli MBS) vials initially rehydrated with 10 ml of sterile distilled water. The Coli MBS vials were closed, shaken for about 30 s for homogenization and then incubated at 37 °C. From the initial red color of the Coli MBS vials, changes in color of the reaction vials were monitored at three different time intervals (12 h, 19 h and 24 h), corresponding to three levels of contamination.ResultsThe average distance (8.7 m) of the latrines from the nearest water source was less than the minimal recommended distance (15 m) to ovoid external contamination. The pH of water samples ranged from 5.5 to 8.3 and the maximum temperature found (26 °C) was almost at level favorable to outbreaks of waterborne diseases such as cholera. The presence of Total Coliforms was detected in 90.91% of the samples. 40% of samples were positive 12 h after the analysis beginning. High level of contamination was observed in unimproved water sources, 50% after 12 h corresponding to Total Coliforms concentration of 10 < x < 103 CFU/ml and the other samples after 19 h (Total Coliforms concentration: 1 < x < 10 CFU/ml).ConclusionThis study revealed the poor microbiological quality of water used by local populations of our study sites. There is need to conduct further qualitative microbiology studies to isolate potential germs involved in outcome of diarrheal diseases.

Water Quality of Underground Wells in Limoeiro do Norte, Brazilian Northeast

The objective of this work was to assess the physicochemical and microbiological characteristics, as well as the potential of salinization and sodification of groundwater wells in Limoeiro do Norte, Cear&amp;aacute; states, Brazil. Six water wells were selected for the study, all of them used for irrigation and human consumption. The ionic classification was performed by Piper Diagram and the salinity risk using the U.S.S.L. (United States Salinity Laboratory) Diagram using Qualigraf software. Based on the average chemical element concentration (mmolc L-1) in the groundwater, the following quantification is obtained: Na+ &amp;gt; Ca2+ &amp;gt; Mg2+ &amp;gt; K+ for cations. For anions there was a change in the the wells, for the 1, 3 and 4 Cl- &amp;gt; HCO3- &amp;gt; SO42- &amp;gt; CO32- and wells 2, 5 and 6 HCO3- &amp;gt; Cl- &amp;gt; SO42- &amp;gt; CO32-. The wells 1, 2 and 3 have severe restrictions for use by SAR (sodium absorption ratio) and Na+ content. Water from wells 1, 3 and 5 were classified as sodium chloride, 2 and 6 were classified as sodium bicarbonate and well 4 as calcium magnesium sulfate. With the exception of well 6 classified as freshwater, all other wells were classified as brackish water. Groundwater samples fall in C3S1 or C3S2 category with high salinity and low or medium sodium hazard. With the exception of Na+, whose value was above the limit allowed, no well with groundwater was detected chemical hazard for human consumption. There was the detection of Total coliforms, but in well 5 the presence of Thermotolerant coliforms was detected.

Nationwide groundwater monitoring around infectious-disease-caused livestock mortality burials in Korea: Superimposed influence of animal leachate on pre-existing anthropogenic pollution

A foot-and-mouth disease (FMD) outbreak during 2010 affected the entire country of South Korea and approximately 3.4 million swine and bovine mortalities were disposed of at approximately 4800 on-farm burial sites for a few months following the first outbreak. Furthermore, outbreaks of avian influenza (AI) have struck Korea consistently since 2014. Public concern regarding the deterioration of the surrounding environment has been raised aiming at the enormous infected animal carcass burials. On behalf of the Ministry of Environment (ME) of the Korean government, we conducted groundwater monitoring at approximately 3000 wells around the burial sites for 7 years from 2011 to 2017. The baseline groundwater already had enriched levels of nitrogen and chloride compounds masking the influence of leachate with the pre-existing anthropogenic contamination. Based on the trend analysis, most monitoring wells had no significant trends in NO3-N and Cl implying that an abrupt degradation in water quality was not expected across the country. Increasing proportions of total coliform detection in the groundwater of the majority of provinces will cause potential damage to human health around the carcass burial sites. Wells showing frequent upward and downward trends near the carcass burial pits were targeted for principal component analysis (PCA) and the results showed that NH4-N, TOC, Cl, and K could be indicators distinguishing the sole impacts of animal leachate on the groundwater. Analyses of the nationwide monitoring data indicated possibly delayed and prolonged impacts of the widespread burials of livestock mortalities on the groundwater environment. The finding provides realistic insight regarding how to manage the mass burial of livestock mortalities to protect groundwater resources.

Calidad microbiológica de la red de distribución de agua potable en Chimaltenango, Guatemala.

Recibido: 12 sep. 2018 Aceptado: 30 oct. 2018&#x0D; Propósito: determinar la calidad microbiológica de la red de distribución de agua potable en los municipios de Patzicía, Patzún, Parramos, Zaragoza, Santa Cruz Balanyá, San Andrés Itzapa y El Tejar, del departamento de Chimaltenango, durante mayo y junio del 2018.&#x0D; Materiales y métodos: estudio prospectivo, descriptivo de corte transversal realizando análisis microbiológico, mediante el método de filtración de membrana para la detección de coliformes totales y Escherichia coli en 43 muestras de agua, proveniente de la totalidad de hidrantes públicos en el área urbana de dichos municipios. Datos obtenidos de los informes del Laboratorio de Análisis Fisicoquímicos y Microbiológicos de la Facultad de Ciencias Químicas y Farmacia de la Universidad de San Carlos de Guatemala, utilizando como referencia los parámetros establecidos por COGUANOR NTG 29001.&#x0D; Resultados: el 76.74% de los hidrantes no son sanitariamente seguros para consumo humano de agua, al detectarse en 33 muestras coliformes totales y 23 contaminadas con E. coli. Además, en Patzún y Santa Cruz Balanyá, el 100% de los hidrantes públicos presentaron contaminación fecal, mientras que en Parramos el 83.33% de los hidrantes abastecen agua potable.&#x0D; Conclusiones: el agua distribuida en el departamento de Chimaltenango no se considera potable, al no cumplir con los límites permisibles establecidos por COGUANOR NTG 29001, detectando 76.74% de muestras analizadas coliformes totales y en 53.49% E. coli. Los municipios en los que se identificó más contaminación del agua son Patzún y Santa Cruz Balanyá, por el contrario Parramos distribuye mayor proporción de agua potable.

Improved detection of Escherichia coli and coliform bacteria by multiplex PCR.

BackgroundThe presence of coliform bacteria is routinely assessed to establish the microbiological safety of water supplies and raw or processed foods. Coliforms are a group of lactose-fermenting Enterobacteriaceae, which most likely acquired the lacZ gene by horizontal transfer and therefore constitute a polyphyletic group. Among this group of bacteria is Escherichia coli, the pathogen that is most frequently associated with foodborne disease outbreaks and is often identified by β-glucuronidase enzymatic activity or by the redundant detection of uidA by PCR. Because a significant fraction of essential E. coli genes are preserved throughout the bacterial kingdom, alternative oligonucleotide primers for specific E. coli detection are not easily identified.ResultsIn this manuscript, two strategies were used to design oligonucleotide primers with differing levels of specificity for the simultaneous detection of total coliforms and E. coli by multiplex PCR. A consensus sequence of lacZ and the orphan gene yaiO were chosen as targets for amplification, yielding 234 bp and 115 bp PCR products, respectively.ConclusionsThe assay designed in this work demonstrated superior detection ability when tested with lab collection and dairy isolated lactose-fermenting strains. While lacZ amplicons were found in a wide range of coliforms, yaiO amplification was highly specific for E. coli. Additionally, yaiO detection is non-redundant with enzymatic methods.

AVALIAÇÃO DA QUALIDADE BACTERIOLÓGICA DA ÁGUA UTILIZADA PARA ABASTECIMENTO PÚBLICO NO MUNICÍPIO DE PELOTAS – RS – BRASIL

Water is a natural resource essential for life and their contamination are a major risk to public health, in addition to causing many environmental problems. This study aimed to evaluate the presence of Pseudomonas aeruginosa, total coliforms and Escherichia coli, from water to public supply of the city of Pelotas/RS. Twelve samples of raw water and twelve of treated water were collected at the Santa Barbara’s Water Treatment Station. Analysis for P. aeruginosa was realized by multiple tube technique, and detection of total coliforms and E. coli was realized by chromogenic substrate method (Fluorocult and Colilert). About raw water samples, 91.7 % indicated growth of P. aeruginosa, E. coli, and 100 % of samples presented positive contamination by total coliforms. Samples of water collected after the treatment did not show any bacterial growth. Results indicate that the treatment system was effective to eliminate the undesirable and pathogenic bacterial. Therefore, the treated water distributed in Pelotas complies with bacteriological parameters established by legislation.

Determinación de la presencia de bacterias patógenas para el humano en aguas de riego en la cuenca alta de la sabana de Bogotá; D.C. Colombia

Determinar la presencia de bacterias patógenas para el humano en aguas de riego en la cuenca alta de la Sabana de Bogotá, Colombia. Materiales y métodos: Se recolectaron 21 muestras en 8 municipios, 8 fueron seleccionadas de forma aleatoria para la determinación de coliformes totales mediante filtración por membrana, número más probable (NMP) para coliformes fecales, aislamiento en medios selectivos e identificación bioquímica con el sistema BDBBL CRYSTAL. Resultados: Se encontró contaminación fecal directa y/o difusa en el 41.7% de muestras y en el 58.3% restante flora normal acuático-terrestre. El porcentaje de E.coli hallado y el recuento de coliformes totales indican que el agua analizada no es apta para el uso agrícola y representa riesgo para la salud.

Mobile Water Kit (MWK): a smartphone compatible low-cost water monitoring system for rapid detection of total coliform and E. coli

In this work, we have developed and demonstrated a rapid and low-cost water monitoring sensor that can simultaneously detect total coliform and Escherichia coli (E. coli) bacteria in contaminated drinking water samples. The test method, called Mobile Water Kit (MWK), comprises a set of custom chemical reagents that would serve as colorimetric or fluorometric chemosensors, syringe filter units and a smartphone platform that would serve as the detection/analysis system. The MWK provides information about the presence/absence of total coliform and E. coli in water samples. The MWK has preliminarily been tested for its selectivity, sensitivity and accuracy, with samples of known concentrations of bacteria. The MWK has also been tested with contaminated water samples collected during the two field trials conducted in Canada and India, and the obtained results were confirmed with conventional laboratory methods. With this MWK, we were able to detect the total coliform and E. coli bacteria in water samples within 30 min or less, depending on the concentration of the bacteria. For one of the field samples, the MWK was able to detect the total coliform within 35 s, which is faster than any rapid test methods available in the market. This new technology can dramatically improve the response times for the outbreak of water-borne diseases and will help water managers and individuals to assess the quality of water sources.

Rapid detection of coliforms in drinking water of Arak city using multiplex PCR method in comparison with the standard method of culture (Most Probably Number)

To analyse molecular detection of coliforms and shorten the time of PCR. Rapid detection of coliforms by amplification of lacZ and uidA genes in a multiplex PCR reaction was designed and performed in comparison with most probably number (MPN) method for 16 artificial and 101 field samples. The molecular method was also conducted on isolated coliforms from positive MPN samples; standard sample for verification of microbial method certificated reference material; isolated strains from certificated reference material and standard bacteria. The PCR and electrophoresis parameters were changed for reducing the operation time. Results of PCR for lacZ and uidA genes were similar in all of standard, operational and artificial samples and showed the 876 bp and 147 bp bands of lacZ and uidA genes by multiplex PCR. PCR results were confirmed by MPN culture method by sensitivity 86% (95% CI: 0.71-0.93). Also the total execution time, with a successful change of factors, was reduced to less than two and a half hour. Multiplex PCR method with shortened operation time was used for the simultaneous detection of total coliforms and Escherichia coli in distribution system of Arak city. It's recommended to be used at least as an initial screening test, and then the positive samples could be randomly tested by MPN.

Molecular method for detection of total coliforms in drinking water samples.

This work demonstrates the ability of a bacterial concentration and recovery procedure combined with three different PCR assays targeting the lacZ, wecG, and 16S rRNA genes, respectively, to detect the presence of total coliforms in 100-ml samples of potable water (presence/absence test). PCR assays were first compared to the culture-based Colilert and MI agar methods to determine their ability to detect 147 coliform strains representing 76 species of Enterobacteriaceae encountered in fecal and environmental settings. Results showed that 86 (58.5%) and 109 (74.1%) strains yielded a positive signal with Colilert and MI agar methods, respectively, whereas the lacZ, wecG, and 16S rRNA PCR assays detected 133 (90.5%), 111 (75.5%), and 146 (99.3%) of the 147 total coliform strains tested. These assays were then assessed by testing 122 well water samples collected in the Québec City region of Canada. Results showed that 97 (79.5%) of the samples tested by culture-based methods and 95 (77.9%), 82 (67.2%), and 98 (80.3%) of samples tested using PCR-based methods contained total coliforms, respectively. Consequently, despite the high genetic variability of the total coliform group, this study demonstrated that it is possible to use molecular assays to detect total coliforms in potable water: the 16S rRNA molecular assay was shown to be as efficient as recommended culture-based methods. This assay might be used in combination with an Escherichia coli molecular assay to assess drinking water quality.

Rapid Detection of Total Coliform and E.Coli in Contaminated Water Using Chemically Modified Microwells

not Available.

Groundwater Risk Assessment Model (GRAM): Groundwater Risk Assessment Model for Wellfield Protection

A groundwater risk assessment was carried out for 30 potable water supply systems under a framework of protecting drinking water quality across South Australia. A semi-quantitative Groundwater Risk Assessment Model (GRAM) was developed based on a “multi-barrier” approach using likelihood of release, contaminant pathway and consequence equation. Groundwater vulnerability and well integrity have been incorporated to the pathway component of the risk equation. The land use of the study basins varies from protected water reserves to heavily stocked grazing lands. Based on the risk assessment, 15 systems were considered as low risk, four as medium and 11 systems as at high risk. The GRAM risk levels were comparable with indicator bacteria—total coliform—detection. Most high risk systems were the result of poor well construction and casing corrosion rather than the land use. We carried out risk management actions, including changes to well designs and well operational practices, design to increase time of residence and setting the production zone below identified low permeable zones to provide additional barriers to contaminants. The highlight of the risk management element is the well integrity testing using down hole geophysical methods and camera views of the casing condition.