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Zhou J, Qu M, Dunkinson C, Lefebvre DD, Wang Y, Brown RS. The Effect of Microcystis on the Monitoring of Faecal Indicator Bacteria. Toxins (Basel) 2023; 15:628. [PMID: 37999491 PMCID: PMC10675124 DOI: 10.3390/toxins15110628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 09/27/2023] [Accepted: 10/07/2023] [Indexed: 11/25/2023] Open
Abstract
The survival of Escherichia coli (E. coli) bacteria, the most common faecal indicator bacteria (FIB), may be significantly affected by cyanobacteria present during a harmful algal bloom (HAB). Therefore, the effect of Microcystis on the survival of FIB E.coli and coliforms was investigated. Microcosms containing two species of Microcystis (M. aeruginosa and M. smithii) were established and then inoculated with four reference strains of E. coli (ATCC 25922, 8739, 51813, and 11775) to explore the cyanobacteria-bacteria dynamics at a laboratory setting. Monitoring over several days showed normal growth of Microcystis, with or without the presence of E. coli. However, Microcystis was shown to dramatically decrease the survival of E. coli over time. Analysis of microcystin production by Microcystis was found to correlate with loss of E. coli, suggesting a toxic effect of microcystins on E. coli bacteria. This phenomenon was also demonstrated for a natural consortium of E. coli and coliform bacteria by inoculating with contaminated lake water. The results indicate that the use of E. coli as FIB may be greatly compromised in the presence of Microcystis spp. such as during a HAB when associated toxins are produced.
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Affiliation(s)
- Jingjing Zhou
- School of Environmental Studies, Queen’s University, Kingston, ON K7L 3N6, Canada; (J.Z.); (C.D.)
| | - Mingzhi Qu
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada; (M.Q.); (Y.W.)
| | - Christy Dunkinson
- School of Environmental Studies, Queen’s University, Kingston, ON K7L 3N6, Canada; (J.Z.); (C.D.)
| | - Daniel D. Lefebvre
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada; (M.Q.); (Y.W.)
| | - Yuxiang Wang
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada; (M.Q.); (Y.W.)
| | - R. Stephen Brown
- School of Environmental Studies, Queen’s University, Kingston, ON K7L 3N6, Canada; (J.Z.); (C.D.)
- Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
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Akita LG, Laudien J, Biney C, Akrong MO. A baseline study of spatial variability of bacteria (total coliform, E. coli, and Enterococcus spp.) as biomarkers of pollution in ten tropical Atlantic beaches: concern for environmental and public health. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:50941-50965. [PMID: 34386920 DOI: 10.1007/s11356-021-15432-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 07/08/2021] [Indexed: 06/13/2023]
Abstract
Coastal water quality in urban cities is increasingly impacted by human activities such as agricultural runoff, sewage discharges, and poor sanitation. However, environmental factors controlling bacteria abundance remain poorly understood. The study employed multiple indicators to assess ten beach water qualities in Ghana during minor wet seasons. Environmental parameters (e.g. temperature, electrical conductivity, total dissolved solids) were measured in situ using the Horiba multiple parameter probe. Surface water samples were collected to measure total suspended solids, nutrients, and chlorophyll-a via standard methods and bacteria determination through membrane filtration. Environmental parameters measured showed no significant variation for the sample period. However, bacteria loads differ significantly (p = 0.024) among the beaches and influenced significantly by nitrate (55.3%, p = 0.02) and total dissolved solids (17.1%, p = 0.017). The baseline study detected an increased amount of total coliforms and faecal indicator bacteria (Escherichia coli and Enterococcus spp.) in beach waters along the coast of Ghana, suggesting faecal contamination, which can pose health risks. The mean ± standard deviations of bacteria loads in beach water are total coliforms (4.06 × 103 ± 4.16 × 103 CFU/100 mL), E. coli (7.06 × 102 ± 1.72 × 103 CFU/100 mL), and Enterococcus spp. (6.15 × 102 ± 1.75 × 103 CFU/100 mL). Evidence of pollution calls for public awareness to prevent ecological and health-related risks and policy reforms to control coastal water pollution. Future research should focus on identifying the sources of contamination in the tropical Atlantic region.
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Affiliation(s)
- Lailah Gifty Akita
- Department of Marine and Fisheries Sciences, University of Ghana, P. O. Box LG 99, Legon, Accra, Ghana.
| | - Juergen Laudien
- Alfred Wegner Institute Helmholtz Centre of Polar and Marine Research, Am Alten Hafen 26, 27568, Bremerhaven, Germany
| | - Charles Biney
- Ecosystems Environmental Solutions, GD-213-5404, Accra, Ghana
| | - Mark Osei Akrong
- CSIR-Research Institute, P.O. Box M 32, GP-018-964, Accra, Ghana
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Tiwari A, Oliver DM, Bivins A, Sherchan SP, Pitkänen T. Bathing Water Quality Monitoring Practices in Europe and the United States. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:5513. [PMID: 34063910 PMCID: PMC8196636 DOI: 10.3390/ijerph18115513] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/14/2021] [Accepted: 05/16/2021] [Indexed: 11/16/2022]
Abstract
Many countries including EU Member States (EUMS) and the United States (U.S.) regularly monitor the microbial quality of bathing water to protect public health. This study comprehensively evaluates the EU bathing water directive (BWD) and the U.S. recreational water quality criteria (RWQC) as regulatory frameworks for monitoring microbial quality of bathing water. The major differences between these two regulatory frameworks are the provision of bathing water profiles, classification of bathing sites based on the pollution level, variations in the sampling frequency, accepted probable illness risk, epidemiological studies conducted during the development of guideline values, and monitoring methods. There are also similarities between the two approaches given that both enumerate viable fecal indicator bacteria (FIB) as an index of the potential risk to human health in bathing water and accept such risk up to a certain level. However, enumeration of FIB using methods outlined within these current regulatory frameworks does not consider the source of contamination nor variation in inactivation rates of enteric microbes in different ecological contexts, which is dependent on factors such as temperature, solar radiation, and salinity in various climatic regions within their geographical areas. A comprehensive "tool-box approach", i.e., coupling of FIB and viral pathogen indicators with microbial source tracking for regulatory purposes, offers potential for delivering improved understanding to better protect the health of bathers.
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Affiliation(s)
- Ananda Tiwari
- Expert Microbiology Unit, Finnish Institute for Health and Welfare, P.O. Box 95, FI-70701 Kuopio, Finland;
| | - David M. Oliver
- Biological and Environmental Sciences, University of Stirling, Stirling FK9 4LA, UK;
| | - Aaron Bivins
- Department of Civil & Environmental Engineering & Earth Science, University of Notre Dame, 156 Fitzpatrick Hall, Notre Dame, IN 46556, USA;
| | - Samendra P. Sherchan
- Department of Environmental Health Sciences, Tulane University, 1440 Canal Street, New Orleans, LA 70112, USA;
| | - Tarja Pitkänen
- Expert Microbiology Unit, Finnish Institute for Health and Welfare, P.O. Box 95, FI-70701 Kuopio, Finland;
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, FI-00014 Helsinki, Finland
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Ahile UJ, Wuana RA, Itodo AU, Sha'Ato R, Malvestiti JA, Dantas RF. Are iron chelates suitable to perform photo-Fenton at neutral pH for secondary effluent treatment? JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 278:111566. [PMID: 33130405 DOI: 10.1016/j.jenvman.2020.111566] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 09/23/2020] [Accepted: 10/21/2020] [Indexed: 06/11/2023]
Abstract
There have been concerns about which iron chelate is most suitable for application in the photo-Fenton process as well as the fate of these chelates after application. In this study, five chelating agents, i.e. citric acid (CA), oxalic acid (OA), ethylenediamine disuccinic acid (EDDS), ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), representing the most used iron chelates were assessed for suitability of application in homogeneous photo-Fenton-like process at pH of 7. The efficiency of the iron chelates were assessed in the disinfection of secondary effluent. The results for the disinfection and bacteria regrowth followed the order EDTA>OA>NTA>CA>OA. All the iron chelates were observed to have increased the COD of the effluent with EDDS having the highest COD contribution. The ability of the chelates to remove aromaticity was measured by the UV254 measurement. The efficiency of the chelates to remove aromaticity decreased in the order CA>EDDS>NTA>CA>OA. To determine the fate of the chelates, toxicity tests were conducted on the chelates before and after irradiation and the results revealed a decrease in toxicity after photoirradiation, implying the chelates were degraded and the products/intermediates produced were of less toxicity as compared to the parent compounds.
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Affiliation(s)
- Ungwanen J Ahile
- Department of Chemistry, Faculty of Science, Benue State University, P.M.B., 102119, Makurdi, Nigeria
| | - Raymond A Wuana
- Department of Chemistry, University of Agriculture, PMB, 2373, Makurdi, Nigeria
| | - Adams U Itodo
- Department of Chemistry, University of Agriculture, PMB, 2373, Makurdi, Nigeria
| | - Rufus Sha'Ato
- Department of Chemistry, University of Agriculture, PMB, 2373, Makurdi, Nigeria
| | - Jacqueline A Malvestiti
- School of Technology, University of Campinas - UNICAMP, Paschoal Marmo 1888, 13484332, Limeira, SP, Brazil
| | - Renato F Dantas
- School of Technology, University of Campinas - UNICAMP, Paschoal Marmo 1888, 13484332, Limeira, SP, Brazil.
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5
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Managing water quality on board passenger vessels to ensure passenger and crew safety. Perspect Public Health 2019; 139:70-74. [PMID: 30880607 DOI: 10.1177/1757913919828960] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Li J, Liu L, Yang D, Liu WL, Shen ZQ, Qu HM, Qiu ZG, Hou AM, Wang DN, Ding CS, Li JW, Guo JH, Jin M. Culture-dependent enumeration methods failed to simultaneously detect disinfectant-injured and genetically modified Escherichia coli in drinking water. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2017; 19:720-726. [PMID: 28406501 DOI: 10.1039/c6em00625f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Underestimation of Escherichia coli in drinking water, an indicator microorganism of sanitary risk, may result in potential risks of waterborne diseases. However, the detection of disinfectant-injured or genetically modified (GM) E. coli has been largely overlooked so far. To evaluate the accuracy of culture-dependent enumeration with regard to disinfectant-injured and GM E. coli, chlorine- or ozone-injured wild-type (WT) and GM E. coli were prepared and characterized. Then, water samples contaminated with these E. coli strains were assayed by four widely used methods, including lactose tryptose broth-based multiple-tube fermentation (MTF), m-endo-based membrane filtration method (MFM), an enzyme substrate test (EST) known as Colilert, and Petrifilm-based testing slip method (TSM). It was found that MTF was the most effective method to detect disinfectant-injured WT E. coli (with 76.9% trials detecting all these bacteria), while this method could not effectively detect GM E. coli (with uninjured bacteria undetectable and a maximal detection rate of 21.5% for the injured). The EST was the only method which enabled considerable enumeration of uninjured GM E. coli, with a detection rate of over 93%. However, the detection rate declined to lower than 45.4% once the GM E. coli was injured by disinfectants. The MFM was invalid for both disinfectant-injured and GM E. coli. This is the first study to report the failure of these commonly used enumeration methods to simultaneously detect disinfectant-injured and GM E. coli. Thus, it highlights the urgent requirement for the development of a more accurate and versatile enumeration method which allows the detection of disinfectant-injured and GM E. coli on the assessment of microbial quality of drinking water.
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Affiliation(s)
- Jing Li
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin 300050, China.
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Vergine P, Salerno C, Barca E, Berardi G, Pollice A. Identification of the faecal indicator Escherichia coli in wastewater through the β-D-glucuronidase activity: comparison between two enumeration methods, membrane filtration with TBX agar, and Colilert ®-18. JOURNAL OF WATER AND HEALTH 2017; 15:209-217. [PMID: 28362302 DOI: 10.2166/wh.2016.119] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Escherichia coli (E. coli) is one of the most commonly adopted indicators for the determination of the microbiological quality in water and treated wastewater. Two main types of methods are used for the enumeration of this faecal indicator: membrane filtration (MF) and enzyme substrate tests. For both types, several substrates based on the β-D-glucuronidase activity have been commercialized. The specificity of this enzyme for E. coli bacteria has generated considerable use of methods that identify the β-D-glucuronidase activity as a definite indication of the presence of E. coli, without any further confirmation. This approach has been recently questioned for the application to wastewater. The present study compares two methods belonging to the above-mentioned types for the enumeration of E. coli in wastewater: MF with Tryptone Bile X-glucuronide agar and the Colilert®-18 test. Confirmation tests showed low average percentages of false positives and false negatives for both enumeration methods (between 4 and 11%). Moreover, the counting capabilities of these two methods were compared for a set of 70 samples of wastewater having different origins and degrees of treatment. Statistical analysis showed that the Colilert®-18 test allowed on average for a significantly higher recovery of E. coli.
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Affiliation(s)
- P Vergine
- IRSA CNR, Viale F. De Blasio, Bari- 5 - 70132, Italy E-mail:
| | - C Salerno
- IRSA CNR, Viale F. De Blasio, Bari- 5 - 70132, Italy E-mail:
| | - E Barca
- IRSA CNR, Viale F. De Blasio, Bari- 5 - 70132, Italy E-mail:
| | - G Berardi
- IRSA CNR, Viale F. De Blasio, Bari- 5 - 70132, Italy E-mail:
| | - A Pollice
- IRSA CNR, Viale F. De Blasio, Bari- 5 - 70132, Italy E-mail:
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Tiwari A, Niemelä SI, Vepsäläinen A, Rapala J, Kalso S, Pitkänen T. Comparison of Colilert-18 with miniaturised most probable number method for monitoring of Escherichia coli in bathing water. JOURNAL OF WATER AND HEALTH 2016; 14:121-131. [PMID: 26837836 DOI: 10.2166/wh.2015.071] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The purpose of this equivalence study was to compare an alternative method, Colilert-18 Quanti-Tray (ISO 9308-2) with the European bathing water directive (2006/7/EC) reference method, the miniaturised most probable number (MMPN) method (ISO 9308-3), for the analysis of Escherichia coli. Six laboratories analysed a total of 263 bathing water samples in Finland. The comparison was carried out according to ISO 17994:2004. The recovery of E. coli using the Colilert-18 method was 7.0% and 8.6% lower than that of the MMPN method after 48 hours and 72 hours of incubation, respectively. The confirmation rate of presumptive E. coli-positive wells in the Colilert-18 and MMPN methods was high (97.8% and 98.0%, respectively). However, the testing of presumptive E. coli-negative but coliform bacteria-positive (yellow but not fluorescent) Colilert-18 wells revealed 7.3% false negative results. There were more false negatives in the naturally contaminated waters than in the samples spiked with waste water. The difference between the recovery of Colilert-18 and the MMPN method was considered not significant, and subsequently the methods are considered as equivalent for bathing water quality monitoring in Finland. Future bathing water method equivalence verification studies may use the data reported herein. The laboratories should make sure that any wells showing even minor fluorescence will be determined as positive for E. coli.
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Affiliation(s)
- Ananda Tiwari
- Water and Health Unit, The National Institute for Health and Welfare, PO Box 95, 70701 Kuopio, Finland E-mail: ; Department of Environmental Science, University of Eastern Finland, Kuopio Campus, PO Box 1627, 70211 Kuopio, Finland
| | | | - Asko Vepsäläinen
- Water and Health Unit, The National Institute for Health and Welfare, PO Box 95, 70701 Kuopio, Finland E-mail:
| | - Jarkko Rapala
- Ministry of Social Affairs and Health, Meritullinkatu 8, 00170 Helsinki, Finland
| | - Seija Kalso
- Metropolilab, Viikinkaari 4, 00790 Helsinki, Finland
| | - Tarja Pitkänen
- Water and Health Unit, The National Institute for Health and Welfare, PO Box 95, 70701 Kuopio, Finland E-mail:
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Abia ALK, Ubomba-Jaswa E, Momba MNB. High prevalence of multiple-antibiotic-resistant (MAR) Escherichia coli in river bed sediments of the Apies River, South Africa. ENVIRONMENTAL MONITORING AND ASSESSMENT 2015; 187:652. [PMID: 26419380 DOI: 10.1007/s10661-015-4879-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 09/16/2015] [Indexed: 06/05/2023]
Abstract
This study aimed at investigating the presence of antibiotic-resistant Escherichia coli in river bed sediments of the Apies River, Gauteng, South Africa, in order to better inform health management decisions designed to protect users of the river. Overall, 180 water and sediment samples were collected at 10 sites along the Apies River from January to February 2014. E. coli was enumerated using the Colilert® 18/Quanti-Tray® 2000 (IDEXX). Isolates were purified by streaking on eosin methylene blue agar followed by the indole test. Pure E. coli isolates were tested for resistance to nine antibiotics by the Kirby-Bauer disc diffusion method. Over 98% of the isolates were resistant to at least one of the antibiotics tested. The highest resistance was observed against nitrofurantoin (sediments) and ampicillin (water). Over 80% of all resistant isolates showed multiple antibiotic resistance (resistance to ≥3 antibiotics). The abundance of E. coli in the sediments not only adds to the evidence that sediments are a reservoir for bacteria and possibly other pathogens including antibiotic-resistant bacteria but also suggests that antibiotic-resistant genes could be transferred to pathogens due to the high prevalence of multiple-antibiotic-resistant (MAR) strains of E. coli observed in the sediment. Using untreated water from the Apies River following resuspension for drinking and other household purposes could pose serious health risks for users. Our results suggest that river bed sediments could serve as reservoirs for MAR bacteria including pathogens under different climatic conditions and their analysis could provide information of public health concerns.
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Affiliation(s)
- Akebe Luther King Abia
- Department of Environmental, Water and Earth Science, Tshwane University of Technology, Arcadia Campus, 175 Nelson Mandela Drive, Private Bag X 680, Pretoria, 0001, South Africa.
| | - Eunice Ubomba-Jaswa
- Natural Resources and the Environment, CSIR, PO Box 395, Pretoria, 0001, South Africa
| | - Maggy Ndombo Benteke Momba
- Department of Environmental, Water and Earth Science, Tshwane University of Technology, Arcadia Campus, 175 Nelson Mandela Drive, Private Bag X 680, Pretoria, 0001, South Africa.
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Brandas V, Orrù G, Carraro V, Sanna A, Brajon G, Salati F, Sanna C, Ciusa ML, Meloni M, Coroneo V. Recovery of Staphylococcus aureus in Gray Mugil cephalus Roe (Bottarga): Investigation by an Integrated Cultural/Molecular Approach. J Food Sci 2015; 80:M1285-90. [PMID: 25944563 DOI: 10.1111/1750-3841.12891] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 03/23/2015] [Indexed: 11/30/2022]
Abstract
In the Mediterranean area, salted and dried roe from the gray Mugil cephalus "bottarga" represent a speciality food with great commercial value. Bottarga is currently produced by a traditional handmade process and, the risk of human bacterial contamination during its manufacturing is still unknown; in this perspective the foodborne pathogen Staphylococcus aureus could potentially contaminate this product due to poor sanitation or bad handling during processing. The aim of this work is: to evaluate the contamination level of foodborne pathogens at different product manufacturing stages and, in addition, to describe a fast and realizable method for the rapid detection of S. aureus in bottarga samples in the field. A cultural procedure was initially used to investigate the occurrence of S. aureus and the other main foodborne pathogens in bottarga samples at the different manufacturing stages (from roe to final product). In addition, a molecular approach was used to rapidly determine the presence of total bacteria, S. aureus, and its potential toxigenicity. Of the 194 specimens analyzed, we identified: Clostridium perfringens, Enterococcus spp. and Enterobacteriaceae. However, some samples resulted as being contaminated with S. aureus (4% in roe and 8.7% in the final product). During the bottarga manufacturing process, we observed an increase in pathogen levels (from 10(2) to 10(5) CFU/g) in contaminated samples, and entA and entB genotypes were identified. Reconstruction experiments suggest that the fresh roe and the bottarga (not completely dried) could represent a risk for the contamination and growth of pathogen bacteria.
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Affiliation(s)
| | - Germano Orrù
- IDNA Sequencing Service (DSS), Univ. di Cagliari, Cagliari, Italy
| | | | - Adriana Sanna
- Public Health Dept, Univ. di Cagliari, Cagliari, Italy
| | - Giovanni Brajon
- IZS of Lazio-Tuscany, State Veterinary Inst, Florence, Italy
| | - Fulvio Salati
- Fish Disease and Aquaculture Centre, IZS of Sardinia State Veterinary Inst., Oristano, Italy
| | - Clara Sanna
- Fish Disease and Aquaculture Centre, IZS of Sardinia State Veterinary Inst., Oristano, Italy
| | | | - Mauro Meloni
- Dipt. di Scienze degli Alimenti, Univ. degli Studi di Udine, Udine, Italy
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Performance Evaluation of an Italian Reference Method, the ISO Reference Method and a Chromogenic Rapid Method for the Detection of E. coli and Coliforms in Bottled Water. FOOD ANAL METHOD 2015. [DOI: 10.1007/s12161-015-0154-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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12
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Buckalew DW, Tuono AJ, Simmons AK, Lankford TW, Smith DH. Homogeneous Distribution of <i>Escherichia coli</i> Measured within the Vertical Water Column of Small, Freshwater Streams. ACTA ACUST UNITED AC 2015. [DOI: 10.4236/jwarp.2015.75033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Saccani G, Bernasconi M, Antonelli M. Optimization of low energy sonication treatment for granular activated carbon colonizing biomass assessment. ENVIRONMENTAL TECHNOLOGY 2014; 35:851-858. [PMID: 24645467 DOI: 10.1080/09593330.2013.853698] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This study is aimed at optimizing a low energy sonication (LES) treatment for granular activated carbon (GAC)-colonizing biomass detachment and determination, evaluating detachment efficiency and the effects of ultrasound exposure on bacterial cell viability. GAC samples were collected from two filters fed with groundwater. Conventional heterotrophic plate count (HPC) and fluorescence microscopy with a double staining method were used to evaluate cell viability, comparing two LES procedures, without and with periodical bulk substitution. A 20 min LES treatment, with bulk substitution after cycles of 5 min as maximum treatment time, allowed to recover 87%/100% of attached biomass, protecting detached bacteria from ultrasound damaging effects. Observed viable cell inactivation rate was 6.5/7.9% cell/min, with membrane-compromised cell damage appearing to be even higher (11.5%/13.1% cell/min). Assessing bacterial detachment and damaging ultrasound effects, fluorescence microscopy turned out to be more sensitive compared to conventional HPC. The optimized method revealed a GAC-colonizing biomass of 9.9 x 10(7) cell/gGAC for plant 1 and 8.8 x 10(7) cell/gGAC for plant 2, 2 log lower than reported in literature. The difference between the two GAC-colonizing biomasses is higher in terms of viable cells (46.3% of total cells in plant 1 GAC-colonizing biomass compared to the 33.3% in plant 2). Studying influent water contamination through multivariate statistical analyses, apossible combined toxic and genotoxic effect of chromium VI and trichloroethylene was suggested as a reason for the lower viable cell fraction observed in plant 2 GAC-colonizing population.
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Garrido L, Sánchez O, Ferrera I, Tomàs N, Mas J. Dynamics of microbial diversity profiles in waters of different qualities. Approximation to an ecological quality indicator. THE SCIENCE OF THE TOTAL ENVIRONMENT 2014; 468-469:1154-1161. [PMID: 24121566 DOI: 10.1016/j.scitotenv.2013.08.065] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 08/20/2013] [Accepted: 08/22/2013] [Indexed: 06/02/2023]
Abstract
Over the past two decades, the amount of reclaimed water has increased throughout the world to face the current water shortage, and as a consequence there is an increasing interest to develop good indicators of water quality, beyond the traditional fecal indicators. In order to meet this need, in this work the microbial profiles of different wastewater treatment plant effluents, both secondary and tertiary, were studied and compared with water samples from an uncontaminated natural aquifer. Taking into account the most abundant phylogenetic groups found in these water samples, we calculated the Bacteroidetes, Gammaproteobacteria and Nitrospira/Betaproteobacteria (BGN:β) ratio and found significant differences between the mean ratios of the four water qualities. The secondary effluent ratios were never below 1.3 and the tertiary effluent and groundwater ratios were never over 0.85. Furthermore, calculation of this index with previous published data supports our results and indicates that the BGN:β ratio is a possible alternative indicator of water quality.
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Affiliation(s)
- L Garrido
- Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Bellaterra, Spain.
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15
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Saleh I, Zouhairi O, Alwan N, Hawi A, Barbour E, Harakeh S. Antimicrobial resistance and pathogenicity ofEscherichia coliisolated from common dairy products in the Lebanon. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2013; 103:39-52. [DOI: 10.1179/136485909x384965] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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16
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Wohlsen TD. Comparative evaluation of chromogenic agar CM1046 and mFC agar for detection of E. coli and thermotolerant coliform bacteria from water samples. Lett Appl Microbiol 2011; 53:155-60. [PMID: 21585405 DOI: 10.1111/j.1472-765x.2011.03086.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS The equivalence of Oxoid (CM 1046) Brilliance((TM)) E. coli/coliform selective agar to mFC agar, as used in the Australian/New Zealand Standard Method to detect thermotolerant coliforms and Escherichia coli in water samples, was assessed. METHODS AND RESULTS A total of 244 water samples were analysed in parallel over a 5-month period. Sewage effluent samples (n = 131, sites = 43), freshwater (n = 62, sites = 18) and marine/brackish water samples (n = 51, sites = 23) were analysed. The Wilcoxon matched-pairs signed-ranks test showed a varying degree of statistical difference between the two methods. All matrices had a higher recovery in the trial method. Enterococci faecalis, Aeromonas spp. and Vibrio spp. did not grow on the CM1046 agar, and Pseudomonas aeruginosa and Enterobacter aerogenes were inhibited. CONCLUSIONS The use of CM 1046 for the detection and enumeration of E. coli and thermotolerant coliforms in water samples is a suitable alternative to the AS/NZS Standard Method. SIGNIFICANCE AND IMPACT OF THE STUDY The use of CM1046 agar was less labour intensive and time consuming, as no secondary confirmation steps were required. Confirmed results could be reported within 24 h of sample analysis, as compared to 48 h with the reference method. Public health concerns can be addressed in a more efficient manner.
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Affiliation(s)
- T D Wohlsen
- Unitywater, Maroochydore Sewage Treatment Plant, Maroochydore, Queensland, Australia.
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Samarajeewa A, Glasauer S, Dunfield K. Evaluation of Petrifilm™ EC method for enumeration ofE. colifrom soil. Lett Appl Microbiol 2010; 50:457-61. [DOI: 10.1111/j.1472-765x.2010.02819.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Fricker CR, Warden PS, Eldred BJ. Understanding the cause of false negative beta-D-glucuronidase reactions in culture media containing fermentable carbohydrate. Lett Appl Microbiol 2010; 50:547-51. [PMID: 20374452 DOI: 10.1111/j.1472-765x.2010.02834.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS To explain the basis for false negative beta-glucuronidase reactions seen with culture media containing lactose as a carbon and energy source. METHODS AND RESULTS Escherichia coli strains were assessed for their reactions in culture media containing a beta-d-glucuronidase substrate either with or without lactose. An assay was developed to test for the expression of beta-D-glucuronidase at pH 5.0 and pH 7.2. Strains of E. coli that gave false negative glucuronidase reactions on media containing lactose generally expressed lower concentrations of the enzyme beta-D-glucuronidase than strains that gave positive results, although the difference was by no means consistent. Most strains that were negative on lactose-containing media expressed virtually no beta-D-glucuronidase activity at pH 5.0. Examination of colonies on Membrane lactose glucuronide agar (MLGA) from lightly polluted water showed that c. 10% of the E. coli present failed to yield green colonies on MLGA. CONCLUSIONS E. coli that failed to produce green colonies on MLGA produced lower levels of beta-D-glucuronidase than did strains that formed green colonies, the difference being greater at pH 5.0 than pH 7.2. The false negative rate for E. coli 10% which is similar to that experienced in the study that originally described MLGA. SIGNIFICANCE AND IMPACT OF THE STUDY Strains of E. coli that fail to produce typical colonies on MLGA might produce lower concentrations of the enzyme beta-D-glucuronidase. Whilst the enzyme activity is sufficient to be detected at pH 7.2, fermentation of lactose significantly lowers the pH of the medium and can result in reduced enzyme activity and therefore lack of detection. The false negative rate of c. 10% would be difficult to detect in routine laboratories as it would represent 1% or less of yellow colonies being identified as E. coli (assuming E. coli accounts for 10% of the total coliform population in drinking water).
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Affiliation(s)
- C R Fricker
- Analytical Services Inc., Williston, VT, USA.
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Kodaka H, Saito M, Matsuoka H. Evaluation of a new most-probable-number (MPN) dilution plate method for the enumeration of Escherichia coli in water samples. Biocontrol Sci 2009; 14:123-6. [PMID: 19785286 DOI: 10.4265/bio.14.123] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
The purpose of this study was to evaluate the most-probable-number dilution plate (MPN plate) method developed for the enumeration of Escherichia coil in water samples. Sterilized water was inoculated with E. coli ATCC 11775 to give between 2-1600 MPN/100 ml. The MPN was determined for both the MPN plate and 5-tube methods from the MPN table. The average of the natural logarithm (In) MPN with standard deviations in 95 samples was 4.26 +/- 1.48 by the 5-tube-method and 4.18 +/- 1.45 by the MPN plate method. The correlation coefficient was 0.96. These results were not significantly different according to the paired t-test (p > 0.05).
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Affiliation(s)
- Hidemasa Kodaka
- Nissui Pharmaceutical Co. Ltd., 1075-2, Hokunanmoro, Yuki, Ibaraki 307-0036, Japan.
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Fricker CR, Eldred BJ. Identification of coliform genera recovered from water using different technologies. Lett Appl Microbiol 2009; 49:685-8. [PMID: 19874482 DOI: 10.1111/j.1472-765x.2009.02726.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS Methods for the detection of coliforms in water have changed significantly in recent years with procedures incorporating substrates for the detection of beta-d-galactosidase becoming more widely used. This study was undertaken to determine the range of coliform genera detected with methods that rely on lactose fermentation and compare them to those recovered using methods based upon beta-d-galactosidase. METHODS AND RESULTS Coliform isolates were recovered from sewage-polluted water using m-endo, membrane lauryl sulfate broth, tergitol TTC agar, Colilert-18, ChromoCult and ColiScan for primary isolation. Organisms were grouped according to whether they had been isolated based upon lactose fermentation or beta-d-galactosidase production. CONCLUSIONS A wide range of coliform genera were detected using both types of methods. There was considerable overlap between the two groups, and whilst differences were seen between the genera isolated with the two method types, no clear pattern emerged. Substantial numbers of 'new' coliforms (e.g. Raoutella spp.) were recovered using both types of methods. SIGNIFICANCE AND IMPACT OF THE STUDY The results presented here confirm that both methods based on lactose fermentation or detection of beta-d-galactosidase activity recover a range of coliform organisms. Any suggestion that only methods which are based upon fermentation of lactose recover organisms of public health or regulatory significance cannot be substantiated. Furthermore, the higher recovery of coliform organisms from sewage-polluted water using methods utilizing beta-d-galactosidase-based methods does not appear to be because of the recovery of substantially more 'new' coliforms.
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Affiliation(s)
- C R Fricker
- Analytical Services Inc., Williston, VT, USA.
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Fremaux B, Boa T, Chaykowski A, Kasichayanula S, Gritzfeld J, Braul L, Yost C. Assessment of the microbial quality of irrigation water in a prairie watershed. J Appl Microbiol 2009; 106:442-54. [DOI: 10.1111/j.1365-2672.2008.04012.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Fricker C, DeSarno M, Warden P, Eldred B. False-negative β-d-glucuronidase reactions in membrane lactose glucuronide agar medium used for the simultaneous detection of coliforms andEscherichia colifrom water. Lett Appl Microbiol 2008; 47:539-42. [DOI: 10.1111/j.1472-765x.2008.02453.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Maheux AF, Huppé V, Boissinot M, Picard FJ, Bissonnette L, Bernier JLT, Bergeron MG. Analytical limits of four β-glucuronidase and β-galactosidase-based commercial culture methods used to detect Escherichia coli and total coliforms. J Microbiol Methods 2008; 75:506-14. [DOI: 10.1016/j.mimet.2008.08.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Revised: 08/04/2008] [Accepted: 08/05/2008] [Indexed: 11/16/2022]
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Hallas G, Giglio S, Capurso V, Monis PT, Grooby WL. Evaluation of chromogenic technologies for use in Australian potable water. J Appl Microbiol 2008; 105:1138-49. [PMID: 18492047 DOI: 10.1111/j.1365-2672.2008.03842.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
AIMS To compare the use of MI agar, Membrane Lactose Glucoronide Agar (MLGA), CM1046 agar and Colilert-18 (Defined Substrate Technology, IDEXX Laboratories Pty. Ltd., Sydney) on Australian potable water. METHODS AND RESULTS Both potable (n = 369) and nonpotable waters (n = 35) were analysed by membrane filtration using chromogenic agars as well as Colilert-18 over a period of 12 months. Recoveries of stressed organisms on these chromogenic media were also investigated. Agar-based chromogenic technologies compared favourably to Colilert-18 for chlorinated waters, but there are possible limitations when using these agars for chloraminated waters. Additionally, the breakthrough of problematic organisms, especially oxidase positive organisms, may lead to misrepresentation or over-estimation of E. coli and total coliforms, particularly on MLGA and CM1046. The recovery of stressed organisms was favoured in the Colilert-18 system when compared to chromogenic agars. CONCLUSIONS MI agar performed better than the other chromogenic agars with respect to recovery and colour identification and discrimination of organisms, and compared favourably with Colilert-18. The use of chromogenic agars in chloraminated waters should be done cautiously. SIGNIFICANCE AND IMPACT OF THE STUDY This study provides comparison data for laboratories looking to adopt chromogenic technologies, and is especially important for Australian laboratories wanting to uptake the use of MI agar (as used in USEPA method 1604) for routine use and for gaining accreditation. Additionally, to the best of our knowledge, this is the first reported evaluation of these agars in chloraminated waters and is especially timely as the use of this disinfection agent is increasing.
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Affiliation(s)
- G Hallas
- Australian Water Quality Centre, SA Water Corporation, Salisbury, SA, Australia
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Pitkänen T, Paakkari P, Miettinen IT, Heinonen-Tanski H, Paulin L, Hänninen ML. Comparison of media for enumeration of coliform bacteria and Escherichia coli in non-disinfected water. J Microbiol Methods 2007; 68:522-9. [PMID: 17150268 DOI: 10.1016/j.mimet.2006.10.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Revised: 10/12/2006] [Accepted: 10/25/2006] [Indexed: 11/21/2022]
Abstract
In this work alternative media for detection and enumeration of E. coli and coliform bacteria were compared to the reference method ISO 9308-1 (LTTC) using non-disinfected water samples with background flora. The alternative media included LES Endo agar medium (LES Endo), Colilert-18 with 51-well Quanti-tray (Colilert), Chromocult Coliform agar (CC), Harlequin E. coli/Coliform medium (HECM) and Chromogenic Escherichia coli/Coliform medium (CECM). A total of 110 samples of groundwater, bathing water and spiked water was used. Our results revealed that confirmation of coliform bacteria counts is necessary, not only on lactose-based LTTC and LES Endo media, but also on the chromogenic agar media tested, due to the growth of oxidase positive colonies. LTTC and CC media also allowed the growth of some morphologically typical coliform colonies containing gram-positive bacteria. The recovery of coliform bacteria was lower on LES Endo than on LTTC. In most cases Colilert, CC, HECM and CECM gave higher coliform counts than LTTC. The use of the LTTC medium led to higher E. coli counts than obtained with any of the alternative mediums. There are three explanations for this: (1) high sensitivity of LTTC, (2) false positives on LTTC or (3) false negatives especially with Colilert, but also with chromogenic agar media. Although LTTC was found to be a very sensitive medium, the high degree of background growth of non-disinfected waters disturbed substantially the use of it. In conclusion, our results suggest that Colilert, CC and CECM are potential alternative media for detection of coliform bacteria and E. coli from non-disinfected water.
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Affiliation(s)
- Tarja Pitkänen
- Laboratory of Environmental Microbiology, National Public Health Institute, P. O. Box 95, FI-70701, Kuopio, Finland.
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Kloot RW, Radakovich B, Huang X, Brantley DD. A comparison of bacterial indicators and methods in rural surface waters. ENVIRONMENTAL MONITORING AND ASSESSMENT 2006; 121:275-87. [PMID: 16741789 DOI: 10.1007/s10661-005-9121-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Accepted: 11/04/2005] [Indexed: 05/09/2023]
Abstract
The United States Environmental Protection Agency (USEPA) recommends the use of Escherichia coli (E. coli) and enterococci as indicators of enteric pathogens in fresh waters; however, fecal coliform analyses will remain important by virtue of the large amount of historic data collected in prior years. In this study, we attempted, in a real-world situation (i.e., a rural inland watershed in the Piedmont of South Carolina) to compare different bacterial indicators and methods to one another. We compared fecal coliforms, enumerated by membrane filtration with E. coli, enumerated by a commercialized enzyme substrate method and observed E. coli/fecal coliform ratios of 1.63 and 1.2 for two separate tests. In the same watershed, we observed an E. coli/fecal coliform ratio of 0.84 when we used the commercialized enzyme substrate method for both enumerations. Given these results, users of such data should exercise care when they make comparisons between historic membrane filtration data and data acquired through the use of the more modern enzymatic methods. Some sampling and side-by-side testing between methods in a specific watershed may be prudent before any conversion factors between old and new datasets are applied.
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Affiliation(s)
- Robin W Kloot
- Earth Sciences and Resources Institute at University of South Carolina, 402 Byrnes Building, Columbia, SC 29208, USA.
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Buckalew DW, Hartman LJ, Grimsley GA, Martin AE, Register KM. A long-term study comparing membrane filtration with Colilert defined substrates in detecting fecal coliforms and Escherichia coli in natural waters. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2006; 80:191-7. [PMID: 16338057 DOI: 10.1016/j.jenvman.2005.08.024] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2005] [Revised: 06/25/2005] [Accepted: 08/29/2005] [Indexed: 05/05/2023]
Abstract
Assessment methods for determining the presence and number of fecal bacteria and Escherichia coli (E. coli) in waters, foodstuffs, sewage effluent, and soils have evolved from multiple tube fermentations (MTF's) to membrane filtrations (MF's) to, most recently, defined substrate technologies (DST's). Mounting evidence indicates Colilert DST (IDEXX, Westbrook, ME) to be a versatile assessment technique for detecting and enumerating E. coli over a range of applications. This study compared the performance of Colilert DST with a confirmed standard MF technique using m-FC broth (Millipore, Bedford, MA) in assessing E. coli in ten different environmental water samples obtained monthly over a 3-year period from the upper Appomattox River, VA. For the duration of the study, E. coli counts measured by Colilert DST were positively correlated (Pearson's correlation coefficient=0.956; slope=0.979; p<0.0001) with E. coli counts measured by confirmed MF procedures. The results of a two-factor ANOVA revealed that Colilert DST counts compared equally to confirmed MF counts by year (p=0.974), by stream sampled (p=1.0), and by season (p=0.696). E. coli counts were significantly lower during cold season months (Dec/Jan/Feb) than during warm season months (Jun/Jul/Aug) for each year contributing to marked variation in sample quality. Counts obtained by Colilert DST compared equally to those obtained by MF across all samples and dates for the three years. Colilert DST presents a laboratory protocol that is simpler to manage, quicker to process, and easier to quantify results than MF. These factors, plus the enhanced precision and versatility of Colilert DST over the span of this three-year study attests to its suitability for testing ambient surface waters.
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Affiliation(s)
- D W Buckalew
- Department of Natural Sciences, Longwood University, Farmville, VA 23909, USA.
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Chao WL. Evaluation of Colilert-18 for the detection of coliforms and Escherichia coli in tropical fresh water. Lett Appl Microbiol 2006; 42:115-20. [PMID: 16441374 DOI: 10.1111/j.1472-765x.2005.01814.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS To evaluate the suitability of Colilert-18 in detecting Escherichia coli and total coliforms in tropical freshwater samples. METHODS AND RESULTS Target organisms were isolated from yellow-fluorescent and yellow wells of Colilert-18/Quanti-Tray using m-TEC agar and m-ENDO LES agar respectively. All the selected isolates were first identified based on their fatty acid methyl ester profile. Isolates showing contradictory results to that of the Colilert-18 procedure were re-identified using API 20E strips. A total of 357 isolates, 177 from yellow-fluorescent wells and 180 from yellow wells, were identified. CONCLUSIONS The false-positive and -negative rates for E. coli detection using Colilert-18 were 36.4% and 11%, respectively, while for coliform detection the false-positive rate was 10.3%. SIGNIFICANCE AND IMPACT OF THE STUDY The high false-positive rate of Colilert-18, tempers its value for E. coli detection when used for tropical freshwater samples.
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Affiliation(s)
- W L Chao
- Department of Microbiology, Soochow University, Shih Lin, Taipei, Taiwan.
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Bonadonna L, Cataldo C, Coccia AM, Chiaretti G, Semproni M. Evaluation of the phenotypic characteristics of coliform bacteria recovered with two methods: the European Drinking Water Directive reference method and the Colilert 18/Quanti-Tray™ system. World J Microbiol Biotechnol 2006. [DOI: 10.1007/s11274-005-9082-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Muirhead RW, Littlejohn RP, Bremer PJ. Evaluation of the effectiveness of a commercially available defined substrate medium and enumeration system for measuring Escherichia coli numbers in faeces and soil samples*. Lett Appl Microbiol 2004; 39:383-7. [PMID: 15355543 DOI: 10.1111/j.1472-765x.2004.01604.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIMS To determine if a commercially available defined substrate medium and enumeration system could be utilized as an effective and accurate means of enumerating Escherichia coli in environmental samples containing faeces and soil. METHODS AND RESULTS The samples tested were either inoculated with laboratory grown E. coli or natural E. coli populations in cow faeces. The number of E. coli recovered from faeces and soil samples using the defined substrate medium and enumeration system and a miniaturized MPN method (using traditional media) was compared by analysing the difference between the two methods in relation to the mean. For four of five groups of samples analysed there was no significant difference in the number of E. coli recovered by the two methods (P > 0.05). In one batch the difference was 0.30 log, which while being statistically significant (P < 0.01) was not considered to be biologically significant. CONCLUSION The commercially available enumeration system was significantly more precise than the miniaturized MPN method (P < 0.001). SIGNIFICANCE AND IMPACT OF THE STUDY We conclude that the commercially available defined substrate medium and enumeration system is a suitable method for the measurement of E. coli numbers in faeces and soil samples and should provide advantages of increased precision and a reduction in laboratory analysis time.
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Affiliation(s)
- R W Muirhead
- Food Science Department, Otago University, Dunedin, New Zealand
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