scholarly journals Validation of Alternative Methods for the Analysis of Drinking Water and Their Application to Escherichia coli

2011 ◽  
Vol 77 (10) ◽  
pp. 3360-3367 ◽  
Author(s):  
Abdelkader Boubetra ◽  
François Le Nestour ◽  
Corrie Allaert ◽  
Max Feinberg
Keyword(s):  
Escherichia Coli ◽  
Drinking Water ◽  
European Commission ◽  
Reference Method ◽  
Alternative Methods ◽  
Coliform Bacteria ◽  
Filtration Method ◽  
Content Type ◽  
Accuracy Profile ◽  
Alternative Method

ABSTRACTIn Europe, the Drinking Water Directive of the European Commission indicates which methods (most of which are CEN/ISO-standardized methods) should be used for the analysis of microbiological parameters (European Commission, Environment, Council Directive 98/83/EC of 3 November 1998). According to the Directive, alternative methods “may be used, providing it can be demonstrated that the results obtained are at least as reliable as those produced by the methods specified.” The prerequisite for the routine use of any alternative method is to provide evidence that this method performs equivalently to the corresponding reference method. In this respect, the ISO 16140 standard (ISO,ISO 16140. Microbiology of Food and Animal Feeding Stuffs—Protocol for the Validation of Alternative Methods, 2003) represents a key issue in generating such a procedure based on an interlaboratory study. A new statistical tool, called the accuracy profile, has been developed to better interpret the data. The study presented here is based upon the enumeration ofEscherichia colibacteria in water. The reference method may require up to 72 h to provide a confirmed result. The aim of this publication is to present data for an alternative method by which results can be obtained in 18 h (Colilert-18/Quanti-Tray) based upon defined substrate technology (DST). The accuracy profile is a statistical and graphical decision-making tool and consists of simultaneously combining, in a single graphic, β expectation tolerance intervals (β-ETIs) and acceptability limits (λ). The study presents the validation criteria calculated at the three levels of contamination used in the trial for a β equal to 80% and a λ equal to ±0.3 and combines the accuracy profiles ofEscherichia colifor a λ of ±0.3 log10unit/100 ml, a λ of ±0.4 log10unit/100 ml, and a β of 80% or 90%. Several interesting conclusions can be drawn from these data. The accuracy profile method has been applied to the validation of the Colilert-18/Quanti-Tray method against reference method ISO 9308-1 (ISO,ISO 9308-1. Water Quality—Detection and Enumeration of Escherichia coli and Coliform Bacteria. Part 1. Membrane Filtration Method, 2000), using a β of 80% and a λ of 0.4; the alternative method can be validated between 1.00 and 2.05 log10units/100 ml, equivalent to 10 to 112 CFU/100 ml.

scholarly journals Escherichia coli O157:H7 in Drin Prevalence of Escherichia coli O157:H7 in Drink from Different Food Premises in Kota Samarahan Sarawak

2019 ◽  
Vol 2 (2) ◽  
pp. a13-19
Author(s):  
ELEXSON NILLIAN ◽  
AMIZA NUR ◽  
DIYANA NUR ◽  
AMIRAH ZAKIRAH ◽  
GRACE BEBEY
Keyword(s):  
Escherichia Coli ◽  
Drinking Water ◽  
Coliform Bacteria ◽  
Most Probable Number ◽  
Plain Water ◽  
Escherichia Coli O157 ◽  
Probable Number ◽  
E Coli ◽  
Preventive Actions ◽  
Stx1 Gene

Contamination of drinks with E. coli O157:H7 served in food premises such as restaurants can cause haemorrhagic colitis and haemolytic uremic syndrome to humans. The presence or absence of faecal pathogen was demonstrated using coliform group as indicator microorganisms. Therefore, this study was conducted to detect the presence of E. coli O157:H7 in drinking water from food restaurant premise in Kota Samarahan and Kuching to ensure safe and potable drinking water is served to the consumer. A total of thirty (n=30) drink samples including six types of each of the samples are cold plain water, iced tea, iced milo, syrup and iced milk tea. Most Probable Number (MPN) procedure was used in this study to enumerate the MPN values of coliform bacteria in each drink collected. A total of 53.33% (16/30) of the drink samples showed positive E. coli detection. Then, the PCR assay showed 6.25% (one out of 16 isolates) samples were positive and carried stx1 gene produced by E. coli O157:H7 in iced milo sample types. This study showed the drinks collected from food premises was contaminated with faecal contamination, which was not safe to drink by the consumer. Therefore, preventive actions should be taken to prevent foodborne illness outbreak in future

scholarly journals EU Drinking Water Directive reference methods for enumeration of total coliforms and Escherichia coli compared with alternative methods

2002 ◽  
Vol 34 (3) ◽  
pp. 227-231 ◽  
Author(s):  
F.M. Schets ◽  
P.J. Nobel ◽  
S. Strating ◽  
K.A. Mooijman ◽  
G.B. Engels ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Drinking Water ◽  
Alternative Methods ◽  
Total Coliforms ◽  
Reference Methods

Comparison of three different media for the detection of E. coli and coliforms in water

2006 ◽  
Vol 54 (3) ◽  
pp. 141-145 ◽  
Author(s):  
C. Bernasconi ◽  
G. Volponi ◽  
L. Bonadonna
Keyword(s):  
Escherichia Coli ◽  
Drinking Water ◽  
Membrane Filtration ◽  
Simultaneous Detection ◽  
Alternative Methods ◽  
Phenotypic Characteristic ◽  
Iso Standard ◽  
E Coli ◽  
Microbiological Parameters ◽  
Filtration Technique

The European Drinking Water Directive defines reference methods for the enumeration of microbiological parameters in drinking water. The method to be used for Escherichia coli and coliforms is the membrane filtration technique on Lactose TTC agar with Tergitol 7. Many technical drawbacks of the procedure, as well as its limitations regarding the recent taxonomy of coliforms, make it necessary to evaluate alternative methods. Two alternative assays, a chromogenic media (m-ColiBlu24®) and a defined substrate technology-DST test (Colilert 18/Quanty Tray™) were compared with the ISO standard with attention to the phenotypic characteristic of the isolates. Results showed that the ISO method failed to detect an important percentage of coliforms and E. coli while m-ColiBlu24® and Colilert 18 provided results in a shorter time allowing the simultaneous detection of E. coli and coliforms with no further confirmation steps.

scholarly journals Pathogenic Potential, Genetic Diversity, and Population Structure of Escherichia coli Strains Isolated from a Forest-Dominated Watershed (Comox Lake) in British Columbia, Canada

2014 ◽  
Vol 81 (5) ◽  
pp. 1788-1798 ◽  
Author(s):  
Abhirosh Chandran ◽  
Asit Mazumder
Keyword(s):  
Escherichia Coli ◽  
Drinking Water ◽  
Population Structure ◽  
Virulence Genes ◽  
Repetitive Element ◽  
Fingerprint Analysis ◽  
Pathogenic Potential ◽  
Content Type ◽  
E Coli ◽  
Heat Stable

ABSTRACTEscherichia coliisolates (n= 658) obtained from drinking water intakes of Comox Lake (2011 to 2013) were screened for the following virulence genes (VGs):stx1andstx2(Shiga toxin-producingE. coli[STEC]),eaeand the adherence factor (EAF) gene (enteropathogenicE. coli[EPEC]), heat-stable (ST) enterotoxin (variants STh and STp) and heat-labile enterotoxin (LT) genes (enterotoxigenicE. coli[ETEC]), andipaH(enteroinvasiveE. coli[EIEC]). The only genes detected wereeaeandstx2, which were carried by 37.69% (n= 248) of the isolates. Onlyeaewas harbored by 26.74% (n= 176) of the isolates, representing potential atypical EPEC strains, while onlystx2was detected in 10.33% (n= 68) of the isolates, indicating potential STEC strains. Moreover, four isolates were positive for both thestx2andeaegenes, representing potential EHEC strains. The prevalence of VGs (eaeorstx2) was significantly (P< 0.0001) higher in the fall season, and multiple genes (eaeplusstx2) were detected only in fall. Repetitive element palindromic PCR (rep-PCR) fingerprint analysis of 658E. coliisolates identified 335 unique fingerprints, with an overall Shannon diversity (H′) index of 3.653. Diversity varied among seasons over the years, with relatively higher diversity during fall. Multivariate analysis of variance (MANOVA) revealed that the majority of the fingerprints showed a tendency to cluster according to year, season, and month. Taken together, the results indicated that the diversity and population structure ofE. colifluctuate on a temporal scale, reflecting the presence of diverse host sources and their behavior over time in the watershed. Furthermore, the occurrence of potentially pathogenicE. colistrains in the drinking water intakes highlights the risk to human health associated with direct and indirect consumption of untreated surface water.

Bacteria removal effectiveness of ceramic pot filters not applied with colloidal silver

2011 ◽  
Vol 11 (6) ◽  
pp. 765-772 ◽  
Author(s):  
K. N. Clark ◽  
A. C. Elmore
Keyword(s):  
Escherichia Coli ◽  
Developing Countries ◽  
Drinking Water ◽  
Coliform Bacteria ◽  
Colloidal Silver ◽  
Safe Drinking Water ◽  
Household Level ◽  
Log Reduction ◽  
Many Sources ◽  
Bacteria Removal

In many developing countries such as Guatemala, access to safe drinking water is very limited. Many sources of water that are available are contaminated with bacteria, particularly Escherichia coli and other coliform bacteria. In order to provide a means of obtaining safe drinking water in developing countries, various methods of treating water at the household level have been developed and implemented throughout the world. One of the more promising treatment mechanisms is the ceramic pot filter, which is typically applied with colloidal silver because of it supposed disinfection purposes. During this study, the bacteria removal effectiveness of 30 filters without colloidal silver was determined by adding water contaminated with Escherichia coli to the filters, and then measuring bacteria concentrations in the filter effluent. The average log reduction values of E. coli and total coliforms determined in this study are 2.1 and 2.3, respectively, and are comparable to other studies of bacteria removal of CPFs. This situation suggests that colloidal silver may indeed not be necessary for the filters to effectively remove bacteria from source water. This study was completed in a period of two weeks, however, while the effect of silver may provide disinfection for several months of use.

scholarly journals Complete Genome Sequence of Escherichia coli Podophage Penshu1

2019 ◽  
Vol 8 (38) ◽  
Author(s):  
Douglas Pechacek ◽  
Myung Hwangbo ◽  
Russell Moreland ◽  
Mei Liu ◽  
Jolene Ramsey
Keyword(s):  
Escherichia Coli ◽  
Complete Genome Sequence ◽  
Complete Genome ◽  
Coliform Bacteria ◽  
Negative Bacterium ◽  
Gram Negative ◽  
Content Type ◽  
E Coli ◽  
Protein Encoding ◽  
Encoding Genes

Escherichia coli 4s is a Gram-negative bacterium found in the equine intestinal ecosystem alongside diverse other coliform bacteria and bacteriophages. This announcement describes the complete genome of the T7-like E. coli 4s podophage Penshu1. From its 39,263-bp genome, 54 protein-encoding genes and a 179-bp terminal repeat were predicted.

scholarly journals The rationale for introducing the indices «Generalized coliform bacteria» and «Escherichia coli» into the scheme of sanitary and microbiological control of water quality as indices of fecal contamination

2021 ◽  
Vol 99 (12) ◽  
pp. 1353-1359
Author(s):  
Angelika V. Zagainova ◽  
Galina M. Trukhina ◽  
Yury A. Rakhmanin ◽  
Tamara Z. Artemova ◽  
Marina A. Sukhina
Keyword(s):  
Escherichia Coli ◽  
Water Quality ◽  
Drinking Water ◽  
Fecal Contamination ◽  
Coliform Bacteria ◽  
E Coli ◽  
Intestinal Infections ◽  
Safety Of Drinking Water ◽  
Microbiological Indicators

Introduction. The increasing bacterial contamination of water bodies requires an increase in water quality control’s reliability to ensure epidemic safety against waterborne infections. Therefore, researchers in both Russia and Europe came to the conclusion that it is necessary to search for indicator microorganisms that can more accurately suggest the presence of pathogens. microorganisms in water than traditional indicators. The aim of the study was to justify the introduction of indicator indices of fecal contamination “generalized coliform bacteria” and Escherichia coli to assess the safety of drinking water Material and methods. The article provides an analysis of domestic and international regulatory documents and literary materials regulating the quality of drinking water in terms of sanitary and microbiological indicators and assessment criteria. The results of many years of experimental and field research carried out by research organizations and practical organizations of the Federal Service for Supervision of Consumer Rights Protection and Human Welfare are presented. Results. On the territory of Russia, “general coliform bacteria,” is one of the indicator indices chosen according to the fermentation of lactose, determine the safety of drinking water. The water does not take into account pathogenic bacteria (Salmonella, Shigella) and a number of lactose-negative opportunistic bacteria, causative agents of intestinal infections. The study of microorganisms isolated from the feces of patients confirms the frequency of occurrence of lactose-negative microorganisms to varying from 20 to 100% of strains. With an annual trend towards a decrease in the percentage of non-standard drinking water samples in terms of microbiological indices, general intestinal infections (GII) of unknown etiology increase, i.e. risk of GII. If the quality of drinking water does not correspond to thermotolerant coliform bacteria (TCB), 95% of samples contain E. coli. Therefore, the determination of E. coli more reliably indicates the intake of fresh fecal contamination and provides efficiency in taking measures to eliminate an unfavorable situation than TCB. Conclusion. Reasons are given for the introduction of more reliable microbiological indicators of water safety control, such as - “generalized coliform bacteria” with the preservation of the abbreviation GCB, combining both lactose-positive and lactose-negative bacteria, determined by the sign of glucose fermentation, negative oxidase test and negative stain according to Gram and E. coli as an indicator of recent faecal contamination, which will allow the assessment of water quality for a wide range of bacteria of the order Enterobacterials, corresponding to the modern taxonomy of Enterobacteriaceae NCBI, will ensure harmonization with international requirements and the safety of drinking water for the population.

scholarly journals Multisite Evaluation of the BD Max Extended Enteric Bacterial Panel for Detection of Yersinia enterocolitica, Enterotoxigenic Escherichia coli, Vibrio, and Plesiomonas shigelloides from Stool Specimens

2017 ◽  
Vol 55 (11) ◽  
pp. 3258-3266 ◽  
Author(s):  
Patricia J. Simner ◽  
Margret Oethinger ◽  
Kathleen A. Stellrecht ◽  
Dylan R. Pillai ◽  
Ram Yogev ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Yersinia Enterocolitica ◽  
Reference Method ◽  
Enterotoxigenic Escherichia Coli ◽  
Plesiomonas Shigelloides ◽  
Content Type ◽  
Culture Techniques ◽  
Discrepant Result ◽  
Percent Agreement ◽  
Stool Specimens

ABSTRACTThe purpose of this study was to perform a multisite evaluation to establish the performance characteristics of the BD Max extended enteric bacterial panel (xEBP) assay directly from unpreserved or Cary-Blair-preserved stool specimens for the detection ofYersinia enterocolitica, enterotoxigenicEscherichia coli(ETEC),Vibrio, andPlesiomonas shigelloides. The study included prospective, retrospective, and prepared contrived specimens from 6 clinical sites. BD Max xEBP results were compared to the reference method, which included standard culture techniques coupled with alternate PCR and sequencing, except for ETEC, for which the reference method was two alternate PCRs and sequencing. Alternate PCR was also used to confirm the historical results for the retrospective specimens and for discrepant result analysis. A total of 2,410 unformed, deidentified stool specimens were collected. The prevalence in the prospective samples as defined by the reference method was 1.2% ETEC, 0.1%Vibrio, 0%Y. enterocolitica, and 0%P. shigelloides. Compared to the reference method, the positive percent agreement (PPA) (95% confidence interval [CI]), negative percent agreement (NPA) (95% CI), and kappa coefficient (95% CI) for the BD Max xEBP assay for all specimens combined were as follows: ETEC, 97.6% (87.4 to 99.6), 99.8% (99.5 to 99.9), and 0.93 (0.87 to 0.99);Vibrio, 100% (96.4 to 100), 99.7% (99.4 to 99.8), and 0.96 (0.93 to 0.99);Y. enterocolitica, 99.0% (94.8 to 99.8), 99.9% (99.8 to 99.9), and 0.99 (0.98 to 1);P. shigelloides, 100% (96.4 to 100), 99.8% (99.5 to 99.9), and 0.98 (0.95 to 1), respectively. In this multicenter study, the BD Max xEBP showed a high correlation (kappa, 0.97; 95% CI, 0.95 to 0.98) with the conventional methods for the detection of ETEC,Vibrio,Y. enterocolitica, andP. shigelloidesin stool specimens from patients suspected of acute gastroenteritis, enteritis, or colitis.

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