Detection of Escherichia coli colonies on confluent plates of chromogenic media used in membrane filtration

Maheux, Andrée F.; Dion-Dupont, Vanessa; Bisson, Marc-Antoine; Bouchard, Sébastien; Rodriguez, Manuel J.

doi:10.1016/j.mimet.2013.12.008

Cited by 8 publications

(4 citation statements)

References 8 publications

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“…Among the microorganisms under surveillance in water treatment, the most famous is likely Escherichia coli, a Gram-negative coccobacillus which is a strong indicator of fecal pollution. In order to monitor the abundance of E. coli in water samples, several methods are currently used, such as the filtering-membrane protocol or the commercialized Colilert kit [2]. These methods are standardized to be used in environmental analysis laboratories and are quite user-friendly to apply.…”

Section: Introductionmentioning

confidence: 99%

Detection of Cryptosporidium spp. and Giardia spp. in Environmental Water Samples: A Journey into the Past and New Perspectives

2022

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Among the major issues linked with producing safe water for consumption is the presence of the parasitic protozoa Cryptosporidium spp. and Giardia spp. Since they are both responsible for gastrointestinal illnesses that can be waterborne, their monitoring is crucial, especially in water sources feeding treatment plants. Although their discovery was made in the early 1900s and even before, it was only in 1999 that the U.S. Environmental Protection Agency (EPA) published a standardized protocol for the detection of these parasites, modified and named today the U.S. EPA 1623.1 Method. It involves the flow-through filtration of a large volume of the water of interest, the elution of the biological material retained on the filter, the purification of the (oo)cysts, and the detection by immunofluorescence of the target parasites. Since the 1990s, several molecular-biology-based techniques were also developed to detect Cryptosporidium and Giardia cells from environmental or clinical samples. The application of U.S. EPA 1623.1 as well as numerous biomolecular methods are reviewed in this article, and their advantages and disadvantages are discussed guiding the readers, such as graduate students, researchers, drinking water managers, epidemiologists, and public health specialists, through the ever-expanding number of techniques available in the literature for the detection of Cryptosporidium spp. and Giardia spp. in water.

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Section: Introductionmentioning

confidence: 99%

Detection of Cryptosporidium spp. and Giardia spp. in Environmental Water Samples: A Journey into the Past and New Perspectives

2022

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“…To minimize interference from nontarget microorganisms, antibiotics and antifungals were included in the formulation of several culture media, while other culture media (e.g. mFC agar) attribute its high specificity to the high incubation temperature (44.5 °C) which limits the growth of nontargeted microorganisms (Hakalehto et al, 2013;Maheux et al, 2014). Nevertheless, several drawbacks (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, several drawbacks (e.g. inability to detect VBNC microorganisms, lack of ubiquity, the viability of the indicator microorganisms is not assured in the time between the sample collection and the analysis, requirement of 18-24 h for detection and sometimes an additional 24-72 h to confirm the positive results) have induced an increasing interest in molecular techniques as a method to achieve a more efficient monitoring of the microbiological water quality (Maheux et al, 2014;Maheux et al, 2012;Maheux et al, 2008;Oliver et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

On the track for an efficient detection of Escherichia coli in water: A review on PCR-based methods

Silva

Domingues

2015

Ecotoxicology and Environmental Safety

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Ensuring water safety is an ongoing challenge to public health providers. Assessing the presence of fecal contamination indicators in water is essential to protect public health from diseases caused by waterborne pathogens. For this purpose, the bacteria Escherichia coli has been used as the most reliable indicator of fecal contamination in water. The methods currently in use for monitoring the microbiological safety of water are based on culturing the microorganisms. However, these methods are not the desirable solution to prevent outbreaks as they provide the results with a considerable delay, lacking on specificity and sensitivity. Moreover, viable but non-culturable microorganisms, which may be present as a result of environmental stress or water treatment processes, are not detected by culture-based methods and, thus, may result in false-negative assessments of E. coli in water samples. These limitations may place public health at significant risk, leading to substantial monetary losses in health care and, additionally, in costs related with a reduced productivity in the area affected by the outbreak, and in costs supported by the water quality control departments involved. Molecular methods, particularly polymerase chain reaction-based methods, have been studied as an alternative technology to overcome the current limitations, as they offer the possibility to reduce the assay time, to improve the detection sensitivity and specificity, and to identify multiple targets and pathogens, including new or emerging strains. The variety of techniques and applications available for PCR-based methods has increased considerably and the costs involved have been substantially reduced, which together have contributed to the potential standardization of these techniques. However, they still require further refinement in order to be standardized and applied to the variety of environmental waters and their specific characteristics. The PCR-based methods under development for monitoring the presence of E. coli in water are here discussed. Special emphasis is given to methodologies that avoid pre-enrichment during the water sample preparation process so that the assay time is reduced and the required legislated sensitivity is achieved. The advantages and limitations of these methods are also reviewed, contributing to a more comprehensive overview toward a more conscious research in identifying E. coli in water.

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“…Cohen's kappa coefficient was used to assess agreement of the Cov-IMS/ATP and Enterolert methods in indicating samples exceeding or in compliance with the threshold of 104 MPN per 100 ml. The kappa coefficient was characterized according to Fleiss (23) guidelines: kappa values over 0.75 were defined as in excellent agreement, values between 0.40 and 0.75 were defined as in fair to good agreement, and kappa values below 0.40 were characterized as in poor agreement (23,24).…”

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confidence: 99%

Performance and Specificity of the Covalently Linked Immunomagnetic Separation-ATP Method for Rapid Detection and Enumeration of Enterococci in Coastal Environments

Zimmer‐Faust

Thulsiraj

Ferguson

et al. 2014

Appl Environ Microbiol

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The performance and specificity of the covalently linked immunomagnetic separation-ATP (Cov-IMS/ATP) method for the detection and enumeration of enterococci was evaluated in recreational waters. Cov-IMS/ATP performance was compared with standard methods: defined substrate technology (Enterolert; IDEXX Laboratories), membrane filtration (EPA Method 1600), and an Enterococcus-specific quantitative PCR (qPCR) assay (EPA Method A). We extend previous studies by (i) analyzing the stability of the relationship between the Cov-IMS/ATP method and culture-based methods at different field sites, (ii) evaluating specificity of the assay for seven ATCC Enterococcus species, (iii) identifying cross-reacting organisms binding the antibody-bead complexes with 16S rRNA gene sequencing and evaluating specificity of the assay to five nonenterococcus species, and (iv) conducting preliminary tests of preabsorption as a means of improving the assay. Cov-IMS/ATP was found to perform consistently and with strong agreement rates (based on exceedance/compliance with regulatory limits) of between 83% and 100% compared to the culture-based Enterolert method at a variety of sites with complex inputs. The Cov-IMS/ATP method is specific to five of seven different Enterococcus spp. tested. However, there is potential for nontarget bacteria to bind the antibody, which may be reduced by purification of the IgG serum with preabsorption at problematic sites. The findings of this study help to validate the Cov-IMS/ATP method, suggesting a predictable relationship between the Cov-IMS/ATP method and traditional culture-based methods, which will allow for more widespread application of this rapid and field-portable method for coastal water quality assessment.

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Detection of Escherichia coli colonies on confluent plates of chromogenic media used in membrane filtration

Cited by 8 publications

References 8 publications

Detection of Cryptosporidium spp. and Giardia spp. in Environmental Water Samples: A Journey into the Past and New Perspectives

Detection of Cryptosporidium spp. and Giardia spp. in Environmental Water Samples: A Journey into the Past and New Perspectives

On the track for an efficient detection of Escherichia coli in water: A review on PCR-based methods

Performance and Specificity of the Covalently Linked Immunomagnetic Separation-ATP Method for Rapid Detection and Enumeration of Enterococci in Coastal Environments

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