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Jia S, Diao Y, Li Y, Zhang J, Han H, Li G, Pei Y. Microbiological interpretation of weak ultrasound enhanced biological wastewater treatment - using Escherichia coli degrading glucose as model system. BIORESOURCE TECHNOLOGY 2024; 403:130873. [PMID: 38782192 DOI: 10.1016/j.biortech.2024.130873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/19/2024] [Accepted: 05/20/2024] [Indexed: 05/25/2024]
Abstract
The Escherichia coli (E.coli) degrading glucose irradiated by ultrasound irradiation (20 W, 14 min) was investigated as the model system, the glucose degradation increased by 13 % while the E.coli proliferation decreased by 10 % after culture for 18 h. It indicated a tradeoff effect between substrate degradation and cell proliferation, which drove the enhanced contaminants removal and excess sludge reduction in a weak ultrasound enhanced biological wastewater treatment. The enzymatic activities (catalase, superoxide dismutase, adenosine triphosphatases, lactic dehydrogenase, membrane permeability, intracellular reactive oxygen species and calcium ion of E. coli increased immediately by 12 %, 63 %, 124 %, 19 %, 15 %, 4-fold and 38-fold, respectively by ultrasound irradiation power of 20 W for 14 min. Furthermore, the membrane permeability of irradiated E. coli increased by 26 % even though the ultrasound stopped for 10 h. Additionally, pathways associated with glucose degradation and cell proliferation were continuously up-regulated and down-regulated, respectively.
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Affiliation(s)
- Shengyong Jia
- School of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, China
| | - Yanfang Diao
- School of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, China
| | - Yingying Li
- School of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, China
| | - Jingshen Zhang
- College of Chemistry, Zhengzhou University, Zhengzhou 450001, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Hongjun Han
- State Key Laboratory of Urban Water Resource & Environment, Harbin Institute of Technology, Harbin 150090, China.
| | - Guirong Li
- School of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, China
| | - Yuanhu Pei
- Henan Qingshuiyuan Technology Co., Ltd, Jiyuan 454650, China
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Madoroba E, Malokotsa KP, Ngwane C, Lebelo S, Magwedere K. Presence and Virulence Characteristics of Shiga Toxin Escherichia coli and Non-Shiga Toxin-Producing Escherichia coli O157 in Products from Animal Protein Supply Chain Enterprises in South Africa. Foodborne Pathog Dis 2022; 19:386-393. [PMID: 35512735 PMCID: PMC9245721 DOI: 10.1089/fpd.2021.0062] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Consumption of food that is contaminated with Shiga toxin-producing Escherichia coli (STEC) has been linked to serious foodborne disease outbreaks. Our aim was to provide a descriptive study on the presence and virulence factors of STEC and non-STEC O157 isolates recovered from 2017 diverse meat and meat product samples from all provinces of South Africa (n = 1758) and imported meat from South Africa's major ports of entry (n = 259). A cross-sectional study was undertaken to analyze raw intact meat, raw processed (nonintact) meat, and ready-to-eat (RTE) meat from cattle, game, sheep, pork, and poultry. Isolation was performed using International Organization for Standardization-based microbiological techniques, while detection and characterization were performed using real-time PCR (RT-PCR) and conventional PCR targeting the stx1, stx2, eae, and ehxA genes. A total of 28 of 1758 (1.59%; confidence interval [CI] 1.1-2) samples from the domestic market tested positive (n = 10 Escherichia coli O157:H7; n = 14 Escherichia coli O157: non-H7; and n = 4 non-O157 STEC), while 4/259 (1.54%; CI 0.4-4) samples from ports of entry tested positive for Escherichia coli O157:H7 based on RT-PCR. On average, diverse samples from domestic meat and meat products from cattle showed the highest number of positive samples (22/1758; 1.3%; CI 0.8-2). RT-PCR detected more positive samples (n = 32) compared with culture (n = 17). Sixteen different virulence factor combinations were observed. Our findings demonstrate a relatively low presence of diverse STEC strains along the meat value chain. To our knowledge, this is the first extensive report in South Africa to analyze STEC and non-STEC O157 from local and imported samples from many animal species. This is important as it reveals virulence factors in STEC strains circulating in meat and meat products in South Africa, which contribute to the risk of infection.
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Affiliation(s)
- Evelyn Madoroba
- Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa, South Africa
| | - Keneiloe Portia Malokotsa
- Bacteriology Section, Agricultural Research Council–Onderstepoort Veterinary Research, Onderstepoort, South Africa
| | - Cynthia Ngwane
- Agricultural Research Council—Biometry Unit, Onderstepoort, South Africa
| | - Sogolo Lebelo
- Agriculture and Life Sciences, University of South Africa, Florida, South Africa
| | - Kudakwashe Magwedere
- Directorate of Veterinary Public Health, Department of Agriculture, Land Reform and Rural Development, Pretoria, South Africa
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Thakur A, Devi P. A Comprehensive Review on Water Quality Monitoring Devices: Materials Advances, Current Status, and Future Perspective. Crit Rev Anal Chem 2022; 54:193-218. [PMID: 35522585 DOI: 10.1080/10408347.2022.2070838] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Water quality monitoring has become more critical in recent years to ensure the availability of clean and safe water from natural aquifers and to understand the evolution of water contaminants across time and space. The conventional water monitoring techniques comprise of sample collection, preservation, preparation, tailed by laboratory testing and analysis with cumbersome wet chemical routes and expensive instrumentation. Despite the high accuracy of these methods, the high testing costs, laborious procedures, and maintenance associated with them don't make them lucrative for end end-users and field testing. As the participation of ultimate stakeholders, that is, common man for water quality and quantity can play a pivotal role in ensuring the sustainability of our aquifers, thus it is essential to develop and deploy portable and user-friendly technical systems for monitoring water sources in real-time or on-site. The present review emphasizes here on possible approaches including optical (absorbance, fluorescence, colorimetric, X-ray fluorescence, chemiluminescence), electrochemical (ASV, CSV, CV, EIS, and chronoamperometry), electrical, biological, and surface-sensing (SPR and SERS), as candidates for developing such platforms. The existing developments, their success, and bottlenecks are discussed in terms of various attributes of water to escalate the essentiality of water quality devices development meeting ASSURED criterion for societal usage. These platforms are also analyzed in terms of their market potential, advancements required from material science aspects, and possible integration with IoT solutions in alignment with Industry 4.0 for environmental application.
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Affiliation(s)
- Anupma Thakur
- Materials Science and Sensor Application, CSIR-Central Scientific Instruments Organisation, Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Pooja Devi
- Materials Science and Sensor Application, CSIR-Central Scientific Instruments Organisation, Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
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Nehoya KN, Hamatui N, Shilangale RP, Onywera H, Kennedy J, Mwapagha LM. Characterization of Shiga toxin-producing Escherichia coli in raw beef from informal and commercial abattoirs. PLoS One 2020; 15:e0243828. [PMID: 33332397 PMCID: PMC7746290 DOI: 10.1371/journal.pone.0243828] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 11/26/2020] [Indexed: 11/19/2022] Open
Abstract
Shiga toxin-producing Escherichia coli are foodborne pathogens that are mostly associated with beef products and have been implicated in human illness. E.coli-associated illness range from asymptomatic conditions of mild diarrhoea to haemorrhagic colitis which can progress into life threatening haemolytic uremic syndrome (HUS). Beef from cattle are regarded as the main reservoir of Shiga toxin-producing E. coli (STEC) pathogen. The aim of this study was to assess the level and sources of contamination of raw beef with STEC, and determine the incidences of STEC strains in raw beef from informal and commercial abattoirs in Windhoek, Namibia. A total of 204 raw beef samples, 37 equipment and 29 hand swabs were collected and tested for STEC. The meat samples were first enriched with pre-warmed buffered peptone water, cultured on Tryptone Bile X-Glucuronide and CHROMagar STEC, and then sub-cultured on nutrient agar. The presence of E.coli in the samples was confirmed by using VITEK 2 E.coli identification cards and PCR. The overall prevalence of STEC in the meat samples from both the abattoirs was 41.66% raw beef samples; 5.40% equipment swabs; and none of the hand swabs was STEC positive. From the STEC positive meat samples 29.41% contained one of the major STEC strains. Moreover, 52% of the 25 samples that contained the major STECs were characterised by eae and stx1, 8% characterised by eae and stx2 while 40% were characterised by eae, stx1 and stx2 virulence genes. This study has revealed the necessity for proper training on meat safety (for meat handlers) as well as the development, implementation and maintenance of effective sanitary dressing procedures at abattoirs to eliminate beef contamination by STECs thereby ensuring the production of wholesome meat, and to prevent the occurrences of STEC infections.
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Affiliation(s)
- Kaarina N. Nehoya
- Department of Health Sciences, Faculty of Health and Applied Sciences, Namibia University of Science and Technology, Windhoek, Namibia
- Directorate of Veterinary Services, Ministry of Agriculture Water and Forestry, Windhoek, Namibia
| | - Ndinomholo Hamatui
- Department of Health Sciences, Faculty of Health and Applied Sciences, Namibia University of Science and Technology, Windhoek, Namibia
| | - Renatus P. Shilangale
- Central Veterinary Laboratory, Ministry of Agriculture Water and Forestry, Windhoek, Namibia
| | - Harris Onywera
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
- Division of Medical Virology, Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Jeya Kennedy
- Department of Natural and Applied Sciences, Faculty of Health and Applied Sciences, Namibia University of Science and Technology, Windhoek, Namibia
| | - Lamech M. Mwapagha
- Department of Natural and Applied Sciences, Faculty of Health and Applied Sciences, Namibia University of Science and Technology, Windhoek, Namibia
- * E-mail:
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Dias D, Caetano T, Torres RT, Fonseca C, Mendo S. Shiga toxin-producing Escherichia coli in wild ungulates. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 651:203-209. [PMID: 30227290 DOI: 10.1016/j.scitotenv.2018.09.162] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/12/2018] [Accepted: 09/12/2018] [Indexed: 06/08/2023]
Abstract
Shiga toxin-producing Escherichia coli (STEC) are zoonotic pathogens that live in the gastrointestinal tract of wildlife and cattle without causing disease. In humans, their colonization and infection lead to life-threatening disease. We investigated the occurrence of STEC in wild ungulates (wild boar, red deer and roe deer) inhabiting areas differently impacted by anthropogenic activities. STEC were detected in 9% (n = 6) of the samples and were recovered from the three species: 1 of wild boar, 4 of red deer and 1 of roe deer. All the isolates (n = 7) were non-O157 STEC encoding stx1 (n = 2; 29%) and/or stx2 genes (n = 6; 86%). O27:H30 was the most frequent serotype identified, followed by O146:H21 and O146:H28. Two STEC were O-untypable: ONT:H28 and ONT:H52. The phylo-groups identified were B1 (n = 3), E (n = 3) and F (n = 1). All the isolates recovered were susceptible to the different classes of antibiotics tested, although resistance genes were found in two strains. Apart from stx, all STEC encode many virulence factors (VF), particularly adhesins and/or other toxins. A strain with 13 VF collected from roe deer has a high enterohemorrhagic risk due to the presence of intimin, hemolysin and protease effectors genes. Enterohemorrhagic E. coli (EHEC) are implicated in the major cases of human infection and mortality, highlighting the zoonotic potential of wildlife-associated STEC. Wild ungulates are reservoirs of STEC potentially pathogenic to humans. Therefore, following the One Health concept, it is crucial to establish worldwide local monitoring programs that will benefit human, animal and environmental health.
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Affiliation(s)
- D Dias
- CESAM and Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | - T Caetano
- CESAM and Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
| | - R T Torres
- CESAM and Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | - C Fonseca
- CESAM and Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | - S Mendo
- CESAM and Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
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Khalil RK, Gomaa MA. Prevalence and characterization of Shiga toxin-producing Escherichia coli (STEC) in fruits and vegetables sold at local street markets in Alexandria, Egypt. Lebensm Wiss Technol 2016. [DOI: 10.1016/j.lwt.2016.07.041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Bonetta S, Pignata C, Lorenzi E, De Ceglia M, Meucci L, Bonetta S, Gilli G, Carraro E. Detection of pathogenic Campylobacter, E. coli O157:H7 and Salmonella spp. in wastewater by PCR assay. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:15302-15309. [PMID: 27106076 DOI: 10.1007/s11356-016-6682-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 04/11/2016] [Indexed: 06/05/2023]
Abstract
The aim of this study was the evaluation of the occurrence of pathogenic Campylobacter, Escherichia coli O157:H7, E. coli virulence genes and Salmonella spp. in different wastewater treatment plants (WWTPs) using a method based on an enrichment step and PCR. This method was sensitive enough to detect low levels (∼2 CFU100 ml(-1) of raw sewage) of all the investigated pathogens. In the WWTP samples, E. coli O157:H7 DNA and the eae gene were never found, but 33 % of influents and effluents exhibited amplicons corresponding to Shiga-like toxin I. Twenty-five percent of the influent and 8 % of the effluent exhibited the presence of Shiga-like toxin II. Campylobacter jejuni and C. coli DNA were identified in 50 and 25 % of the influents and in 8 and 25 % of the effluents, respectively. Salmonella spp. DNA was present in all the samples. Considering the results obtained, the method tested here offers a reliable and expeditious tool for evaluating the efficiency of the effluent treatment in order to mitigate contamination risk. Influent contamination by Salmonella spp. and Campylobacter spp. provides indirect information about their circulation; moreover, their presence in effluents underlines the role of WWTPs in the contamination of the receiving surface waters, which affects public health directly or indirectly.
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Affiliation(s)
- Si Bonetta
- Department of Public Health and Pediatrics, University of Torino, Via Santena 5 bis, 10126, Torino, Italy
| | - C Pignata
- Department of Public Health and Pediatrics, University of Torino, Via Santena 5 bis, 10126, Torino, Italy
| | - E Lorenzi
- Società Metropolitana Acque Torino S.p.A., C.so XI Febbraio, 14, Torino, 10152, Italy
| | - M De Ceglia
- Società Metropolitana Acque Torino S.p.A., C.so XI Febbraio, 14, Torino, 10152, Italy
| | - L Meucci
- Società Metropolitana Acque Torino S.p.A., C.so XI Febbraio, 14, Torino, 10152, Italy
| | - Sa Bonetta
- Department of Public Health and Pediatrics, University of Torino, Via Santena 5 bis, 10126, Torino, Italy
| | - G Gilli
- Department of Public Health and Pediatrics, University of Torino, Via Santena 5 bis, 10126, Torino, Italy
| | - E Carraro
- Department of Public Health and Pediatrics, University of Torino, Via Santena 5 bis, 10126, Torino, Italy.
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Ranjbar R, Erfanmanesh M, Afshar D, Mohammadi M, Ghaderi O, Haghnazari A. Visual Detection of Enterohemorrhagic Escherichia coli O157:H7 Using Loop-Mediated Isothermal Amplification. Electron Physician 2016; 8:2576-85. [PMID: 27504175 PMCID: PMC4965210 DOI: 10.19082/2576] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Accepted: 01/20/2016] [Indexed: 11/20/2022] Open
Abstract
INTRODUCTION Escherichia coli O157:H7, an important foodborne pathogen, can cause serious renal damage, which can also lead to mortality. Since a rapid and sensitive method is needed to identify this pathogenic agent, we evaluated Loop-Mediated Isothermal Amplification Assay (LAMP) to detect Escherichia coli O157:H7. METHODS We used six primers that specifically identified the rfbE gene. To examine the sensitivity of the method, different dilutions were subjected to the LAMP reaction. Other bacterial strains also were investigated to determine the specificity of the test. The turbidity of the amplified products was assayed by visual detection. The amplified products were detected by addition of SYBR Green II to the reaction tubes. RESULTS Amplification products were observed as a ladder-like pattern on the agarose gel. A white turbidity emerged in the positive tubes. Under UV light, the positive samples were green, whereas the negative samples were orange. The detection limit of the LAMP was 78 pg/tube, and this indicated that it was 100 times more sensitive than PCR for the detection of EHEC. No LAMP products were detected when template DNA of non-EHEC strains were used, suggesting high specificity of the LAMP assay. CONCLUSION The results indicated that the LAMP assay is a valuable diagnostic assay to identify EHEC O157:H7. In addition, the simplicity, sensitivity, specificity, and rapidity of this assay make it a useful method to diagnose pathogens in primary labs without any need for expensive equipment or specialized techniques.
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Affiliation(s)
- Reza Ranjbar
- Ph.D. of Medical Bacteriology, Professor, Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Maryam Erfanmanesh
- M.Sc. of Biotechnology, Department of Agriculture and Plant Breeding, Faculty of Agriculture, Zanjan University, Zanjan, Iran
| | - Davoud Afshar
- Ph.D. of Medical Bacteriology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohsen Mohammadi
- Ph.D. of Pharmaceutical Biotechnology, Assistant Professor, Department of Pharmaceutical Biotechnology, Faculty of Pharmacy, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Omar Ghaderi
- Ph.D. Candidate of Pharmaceutical Biotechnology, Department of Pharmaceutical Biotechnology, Tehran University of Medical Sciences, Tehran, Iran
| | - Ali Haghnazari
- Department of Agriculture and Plant Breeding, Faculty of Agriculture, Zanjan University, Zanjan, Iran
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Noll LW, Shridhar PB, Shi X, An B, Cernicchiaro N, Renter DG, Nagaraja TG, Bai J. A Four-Plex Real-Time PCR Assay, Based on rfbE, stx1, stx2, and eae Genes, for the Detection and Quantification of Shiga Toxin-Producing Escherichia coli O157 in Cattle Feces. Foodborne Pathog Dis 2015; 12:787-94. [PMID: 26317538 DOI: 10.1089/fpd.2015.1951] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Several real-time polymerase chain reaction (PCR) assays have been developed to detect and quantify Shiga toxin-producing Escherichia coli (STEC) O157:H7, but none have targeted the O-antigen specific gene (rfbEO157) in combination with the three major virulence genes, stx1, stx2, and eae. Our objectives were to develop and validate a four-plex, quantitative PCR (mqPCR) assay targeting rfbE(O157), stx1, stx2, and eae for the detection and quantification of STEC O157 in cattle feces, and compare the applicability of the assay to detect STEC O157 to a culture method and conventional PCR (cPCR) targeting the same four genes. Specificity of the mqPCR assay to differentially detect the four genes was confirmed with strains of O157 and non-O157 STEC with different profiles of target genes. In cattle feces spiked with pure cultures, detection limits were 2.8×10(4) and 2.8×10(0) colony-forming units/g before and after enrichment, respectively. Detection of STEC O157 in feedlot cattle fecal samples (n=278) was compared between mqPCR, cPCR, and a culture method. The mqPCR detected 48.9% (136/278) of samples as positive for E. coli O157. Of the 100 samples that were randomly picked from 136 mqPCR-positive samples, 35 and 48 tested positive by cPCR and culture method, respectively. Of the 100 samples randomly chosen from 142 mqPCR-negative samples, all were negative by cPCR, but 21 samples tested positive by the culture method. McNemar's chi-square tests indicated significant disagreement between the proportions of positive samples detected by the three methods. In conclusion, the mqPCR assay that targets four genes is a novel and more sensitive method than the cPCR or culture method to detect STEC O157 in cattle feces. However, the use of real-time PCR as a screening method to identify positive samples and then subjecting only positive samples to a culture method may underestimate the presence of STEC O157 in fecal samples.
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Affiliation(s)
- Lance W Noll
- 1 Department of Diagnostic Medicine/Pathobiology, Kansas State University , Manhattan, Kansas
| | - Pragathi B Shridhar
- 1 Department of Diagnostic Medicine/Pathobiology, Kansas State University , Manhattan, Kansas
| | - Xiaorong Shi
- 1 Department of Diagnostic Medicine/Pathobiology, Kansas State University , Manhattan, Kansas
| | - Baoyan An
- 2 Department of Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Kansas State University , Manhattan, Kansas
| | - Natalia Cernicchiaro
- 1 Department of Diagnostic Medicine/Pathobiology, Kansas State University , Manhattan, Kansas
| | - David G Renter
- 1 Department of Diagnostic Medicine/Pathobiology, Kansas State University , Manhattan, Kansas
| | - Tiruvoor G Nagaraja
- 1 Department of Diagnostic Medicine/Pathobiology, Kansas State University , Manhattan, Kansas
| | - Jianfa Bai
- 2 Department of Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Kansas State University , Manhattan, Kansas
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Mendes Silva D, Domingues L. On the track for an efficient detection of Escherichia coli in water: A review on PCR-based methods. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2015; 113:400-11. [PMID: 25540852 DOI: 10.1016/j.ecoenv.2014.12.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 12/03/2014] [Accepted: 12/08/2014] [Indexed: 05/11/2023]
Abstract
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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Affiliation(s)
- Diana Mendes Silva
- CEB-Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal.
| | - Lucília Domingues
- CEB-Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal.
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Comparison of recto-anal mucosal swab and faecal culture for the detection of Escherichia coli O157 and identification of super-shedding in a mob of Merino sheep. Epidemiol Infect 2015; 143:2733-42. [PMID: 25613185 DOI: 10.1017/s0950268815000011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
We compared the use of recto-anal mucosal swab (RAMS) culture and faecal culture for the detection of E. coli O157 in a mob of Merino sheep. Fifty Merino wethers and maiden ewes housed in indoor pens were sampled on five occasions. We detected E coli O157 in 32% (16/50) of sheep, with weekly prevalence ranging from 4% (2/50) to 16% (8/50). Overall, 12·5% (2/16) were detected by RAMS culture only, and 37·5% (6/16) were detected by faecal culture only. The level of agreement between the two sampling methods was moderate [kappa statistic = 0·583, 95% confidence interval (CI) 0·460-0·707]. The relative sensitivities of RAMS and faecal culture were 67% (95% CI 41-86) and 57% (95% CI 34-77), respectively. We identified four super-shedding sheep using direct faecal culture. Although the majority of culture-positive sheep were detected at one sampling point only, 3/4 super-shedding sheep were culture-positive at two sampling points, and 1/4 was culture-positive at four sampling points. Persistent culture positivity may indicate sheep that could be considered 'super-shedders' at some point. The use of immunomagnetic separation further improved the rate of detection of E. coli O157, which was isolated from 1/34 animals that were previously negative by enrichment culture alone. A significant difference between sampling weeks was detected for both faecal (P = 0·021) and RAMS (P = 0·006), with the prevalence at the mid-point of sampling (week 4) significantly (P < 0·05) higher than at the beginning or end of the study. Study conditions (penned sheep) might have been responsible for the high prevalence and the epidemic pattern of infection observed, and could serve as a future model for studies of E. coli O157 transmission, shedding and super-shedding in sheep.
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Williams K, Ward M, Dhungyel O, Hall E, Van Breda L. A longitudinal study of the prevalence and super-shedding of Escherichia coli O157 in dairy heifers. Vet Microbiol 2014; 173:101-9. [DOI: 10.1016/j.vetmic.2014.07.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 06/28/2014] [Accepted: 07/04/2014] [Indexed: 12/13/2022]
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Risk factors for Escherichia coli O157 shedding and super-shedding by dairy heifers at pasture. Epidemiol Infect 2014; 143:1004-15. [PMID: 24977432 DOI: 10.1017/s0950268814001630] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We undertook a longitudinal study within a cohort of 52 dairy heifers maintained under constant management systems and sampled weekly to investigate a comprehensive range of risk factors which may influence shedding or super-shedding of E. coli O157 (detected by direct faecal culture and immunomagnetic separation). E. coli O157 was detected from 416/933 (44.6%) samples (faeces and recto-anal mucosal swabs) and 32 (3.4%) samples enumerated at >10000 c.f.u./g. Weekly point prevalence ranged from 9.4% to 94.3%. Higher temperature (P < 0.001), rainfall (P = 0.02), relative humidity (P < 0.001), pasture growth (P = 0.013) and body score (P = 0.029) were positively associated with increased shedding. Higher rainfall (P < 0.001), hide contamination (P = 0.002) and increased faecal consistency (P = 0.023) were positively associated with super-shedding. Increased solar exposure had a negative effect on both shedding and super-shedding within bivariate analyses but in the final multivariate model for shedding demonstrated a positive effect (P = 0.017). Results suggest that environmental factors are important in E. coli O157 shedding in cattle.
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Varela AR, Manaia CM. Human health implications of clinically relevant bacteria in wastewater habitats. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2013; 20:3550-3569. [PMID: 23508533 DOI: 10.1007/s11356-013-1594-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 02/25/2013] [Indexed: 06/01/2023]
Abstract
The objective of this review is to reflect on the multiple roles of bacteria in wastewater habitats with particular emphasis on their harmful potential for human health. Indigenous bacteria promote a series of biochemical and metabolic transformations indispensable to achieve wastewater treatment. Some of these bacteria may be pathogenic or harbour antibiotic resistance or virulence genes harmful for human health. Several chemical contaminants (heavy metals, disinfectants and antibiotics) may select these bacteria or their genes. Worldwide studies show that treated wastewater contain antibiotic resistant bacteria or genes encoding virulence or antimicrobial resistance, evidencing that treatment processes may fail to remove efficiently these bio-pollutants. The contamination of the surrounding environment, such as rivers or lakes receiving such effluents, is also documented in several studies. The current state of the art suggests that only some of antibiotic resistance and virulence potential in wastewater is known. Moreover, wastewater habitats may favour the evolution and dissemination of new resistance and virulence genes and the emergence of new pathogens. For these reasons, additional research is needed in order to obtain a more detailed assessment of the long-term effects of wastewater discharges. In particular, it is important to measure the human and environmental health risks associated with wastewater reuse.
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Affiliation(s)
- Ana Rita Varela
- CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino de Almeida, 4200-072, Porto, Portugal
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15
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Sbodio A, Maeda S, Lopez-Velasco G, Suslow TV. Modified Moore swab optimization and validation in capturing E. coli O157:H7 and Salmonella enterica in large volume field samples of irrigation water. Food Res Int 2013. [DOI: 10.1016/j.foodres.2013.01.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Thapa SP, Han AR, Cho JM, Hur JH. Multiplex PCR and DNA array for the detection of Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella spp. targeting virulence-related genes. ANN MICROBIOL 2012. [DOI: 10.1007/s13213-012-0526-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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17
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Bai J, Paddock ZD, Shi X, Li S, An B, Nagaraja TG. Applicability of a Multiplex PCR to Detect the Seven Major Shiga Toxin–ProducingEscherichia coliBased on Genes That Code for Serogroup-Specific O-Antigens and Major Virulence Factors in Cattle Feces. Foodborne Pathog Dis 2012; 9:541-8. [DOI: 10.1089/fpd.2011.1082] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Jianfa Bai
- Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, Kansas
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas
| | - Zachary D. Paddock
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas
| | - Xiaorong Shi
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas
| | - Shubo Li
- Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, Kansas
- Liaoning Center for Animal Epidemic Disease Control and Prevention, Shenyang, Liaoning, China
| | - Baoyan An
- Veterinary Diagnostic Laboratory, Kansas State University, Manhattan, Kansas
| | - Tiruvoor G. Nagaraja
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas
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18
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Jacob ME, Shi X, An B, Nagaraja TG, Bai J. Evaluation of a multiplex real-time polymerase chain reaction for the quantification of Escherichia coli O157 in cattle feces. Foodborne Pathog Dis 2011; 9:79-85. [PMID: 22047056 DOI: 10.1089/fpd.2011.0947] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cattle are asymptomatic reservoirs for Escherichia coli O157, a major foodborne pathogen. The organism generally colonizes the hindgut of cattle and is shed in the feces at low concentrations. The objective of this research was to evaluate a multiplex, real-time polymerase chain reaction (mqPCR) assay for quantification of E. coli O157 in cattle feces using stx1, stx2, and rfbE gene targets. Primer efficiency and analytical sensitivity of the assay were evaluated with a single or pooled (five strain) culture of E. coli O157. In pure culture, the minimum detection limit of the assay was 1.4×10(3) CFU/mL and 3.6×10(3) CFU/mL for the single and five-strain mixture of E. coli O157, respectively. Diagnostic sensitivity was analyzed using DNA extracted from cattle feces spiked with E. coli O157. In feces spiked with the pooled mixture of five E. coli O157 strains, the minimum detection limit was 3.6×10(4) CFU/g. We also evaluated the assay with feces from cattle experimentally inoculated with E. coli O157 by comparing the results to a culture-based method. For the majority of samples tested, the concentration of E. coli O157 detected by the real-time and culture methods was within one log difference. However, the assay could only be evaluated for cattle shedding high concentrations of E. coli O157. In conclusion, the mqPCR quantifying E. coli O157 in cattle feces using stx1, stx2, and rfbE gene targets may have use in detecting and quantifying super shedders, but is not applicable for quantification in animals shedding low concentrations (10(2) to 10(3) CFU/g feces).
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Affiliation(s)
- Megan E Jacob
- Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA
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Iguchi A, Shirai H, Seto K, Ooka T, Ogura Y, Hayashi T, Osawa K, Osawa R. Wide distribution of O157-antigen biosynthesis gene clusters in Escherichia coli. PLoS One 2011; 6:e23250. [PMID: 21876740 PMCID: PMC3158064 DOI: 10.1371/journal.pone.0023250] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 07/12/2011] [Indexed: 11/20/2022] Open
Abstract
Most Escherichia coli O157-serogroup strains are classified as enterohemorrhagic E. coli (EHEC), which is known as an important food-borne pathogen for humans. They usually produce Shiga toxin (Stx) 1 and/or Stx2, and express H7-flagella antigen (or nonmotile). However, O157 strains that do not produce Stxs and express H antigens different from H7 are sometimes isolated from clinical and other sources. Multilocus sequence analysis revealed that these 21 O157:non-H7 strains tested in this study belong to multiple evolutionary lineages different from that of EHEC O157:H7 strains, suggesting a wide distribution of the gene set encoding the O157-antigen biosynthesis in multiple lineages. To gain insight into the gene organization and the sequence similarity of the O157-antigen biosynthesis gene clusters, we conducted genomic comparisons of the chromosomal regions (about 59 kb in each strain) covering the O-antigen gene cluster and its flanking regions between six O157:H7/non-H7 strains. Gene organization of the O157-antigen gene cluster was identical among O157:H7/non-H7 strains, but was divided into two distinct types at the nucleotide sequence level. Interestingly, distribution of the two types did not clearly follow the evolutionary lineages of the strains, suggesting that horizontal gene transfer of both types of O157-antigen gene clusters has occurred independently among E. coli strains. Additionally, detailed sequence comparison revealed that some positions of the repetitive extragenic palindromic (REP) sequences in the regions flanking the O-antigen gene clusters were coincident with possible recombination points. From these results, we conclude that the horizontal transfer of the O157-antigen gene clusters induced the emergence of multiple O157 lineages within E. coli and speculate that REP sequences may involve one of the driving forces for exchange and evolution of O-antigen loci.
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Affiliation(s)
- Atsushi Iguchi
- Interdisciplinary Research Organization, University of Miyazaki, Miyazaki, Japan.
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20
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Bonetta S, Borelli E, Bonetta S, Conio O, Palumbo F, Carraro E. Development of a PCR protocol for the detection of Escherichia coli O157:H7 and Salmonella spp. in surface water. ENVIRONMENTAL MONITORING AND ASSESSMENT 2011; 177:493-503. [PMID: 20714926 DOI: 10.1007/s10661-010-1650-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 07/29/2010] [Indexed: 05/29/2023]
Abstract
Escherichia coli O157:H7 and Salmonella are pathogenic microorganisms that can cause severe gastrointestinal illness in humans. These pathogens may be transmitted in a variety of ways, including food and water. The presence of Salmonella and E. coli O157:H7 in surface waters constitutes a potential threat to human health when used for either drinking or recreation. As with most waterborne pathogens, Salmonella and E. coli O157:H7 are difficult to detect and enumerate with accuracy in surface waters due to methodological limitations. The aim of this study was to develop a protocol for the detection of Salmonella spp., E. coli O157:H7 and E. coli virulence genes (stx (1), stx (2) and eae) in water using a single enrichment step and PCR. In spiked water samples, PCR results showed high sensitivity (<3 CFU/L) for both microorganisms. The protocol developed in this study has been applied in different surface waters in association with microbiological and physical analysis. The frequency of PCR positive samples was 33% for Salmonella and 2% for E. coli O157:H7 producing intimin (eae) and Shiga-like toxin I (stx (1)). Moreover, the finding of amplicons corresponding to eae and stx (1) genes in the absence of E. coli O157:H7 suggested the possible presence of other pathogenic bacteria that carry these genes (e.g. EHEC, Shigella strains). The results obtained showed that the developed protocol could be applied as a routine analysis of surface water for the evaluation of microbiological risks.
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Affiliation(s)
- Silvia Bonetta
- Dipartimento di Scienze dell'Ambiente e della Vita, Università degli Studi del Piemonte Orientale, "A. Avogadro", via T. Michel 11, 15121 Alessandria, Italy
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21
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Clark ST, Gilbride KA, Mehrvar M, Laursen AE, Bostan V, Pushchak R, McCarthy LH. Evaluation of low-copy genetic targets for waterborne bacterial pathogen detection via qPCR. WATER RESEARCH 2011; 45:3378-3388. [PMID: 21514618 DOI: 10.1016/j.watres.2011.03.050] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 03/08/2011] [Accepted: 03/27/2011] [Indexed: 05/30/2023]
Abstract
Recent developments in water quality research have highlighted difficulties in accurately predicting the incidence of pathogens within freshwater based on the viability, culturability and metabolic activity of indicator organisms. QPCR-driven assays are candidates to replace standard culture-based methods, however, protocols suitable for routine use have yet to be sufficiently validated. The objective of this study was to evaluate five oligonucleotide primers sets (ETIR, SINV, exoT, VS1 and ipaH2) for their potential applicability in qPCR assays to detect contamination from five waterborne bacterial pathogens (Escherichia coli O157:H7, Salmonella Typhimurium, Campylobacter jejuni, Pseudomonas aeruginosa, and Shigella flexneri). An enrichment-free qPCR protocol was also tested using S. Typhimurium-seeded source water, combining membrane filtration and mechanical, chemical and enzymatic lysis techniques to recover the bacterial cells. All five primer sets were found to have high specificity and sensitivity for the tested organisms. Four of the primers were able to detect pathogen loads as low as 10 cells/mL while 200 cells/mL of C. jejuni were detectable in pure culture. Although sensitivity decreased in an artificially contaminated environmental matrix, it was still possible to detect as few as 10 S. Typhimurium cells without enrichment. The primers and protocols evaluated in this study have demonstrated potential for further validation for possible application alongside traditional indicator techniques.
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Affiliation(s)
- Shawn T Clark
- Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3, Canada
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22
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Development of PCR assays for detection of Escherichia coli O157:H7 in meat products. Meat Sci 2011; 88:767-73. [PMID: 21458168 DOI: 10.1016/j.meatsci.2011.03.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 03/04/2011] [Accepted: 03/08/2011] [Indexed: 11/22/2022]
Abstract
A multiplex polymerase chain reaction (PCR) procedure based on fliC(h7) and rfbE genes was developed for the detection of Escherichia coli O157:H7 in raw pork meat and ready-to-eat (RTE) meat products. Two different DNA extraction procedures were evaluated for application on meat products. MasterPure™ DNA Purification kit in combination with immunomagnetic separation was found to be the best method in a meat system. The optimized PCR included an enrichment step in brilliant green bile 2% broth at 37 °C. This method was applied to artificially inoculated meat and RTE meat products with different concentrations of E. coli O157:H7. The results indicate that the PCR assay developed could sensitively and specifically detect E. coli O157:H7 in raw pork meat and RTE meat products in approximately 10h, including a 6h enrichment step. Thus, this method could be proposed for screening E. coli O157:H7 in raw pork and RTE meat products.
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23
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Parallel analysis of 7 food-borne pathogens using capillary electrophoresis-based single-strand conformation polymorphism. Food Sci Biotechnol 2010. [DOI: 10.1007/s10068-010-0206-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Jacob ME, Renter DG, Nagaraja TG. Animal- and truckload-level associations between Escherichia coli O157:H7 in feces and on hides at harvest and contamination of preevisceration beef carcasses. J Food Prot 2010; 73:1030-7. [PMID: 20537257 DOI: 10.4315/0362-028x-73.6.1030] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cattle feces and hides contribute to carcass contamination with Escherichia coli O157:H7, ultimately impacting beef safety. Primary objectives of our cross-sectional study were to evaluate associations among fecal, hide, and preevisceration carcass prevalence of E. coli O157:H7 and to assess factors affecting carcass contamination. Fecal, hide, and preevisceration carcass samples were collected from up to 32 cattle on each of 45 truckloads presented to a midwestern U.S. abattoir. Enrichment and selective culture were used to assess fecal, hide, and carcass prevalence, and direct plating was used to identify cattle shedding high levels of E. coli O157:H7 in feces. Fecal, hide, and carcass prevalence of E. coli O157:H7 within truckload were significantly correlated (P < 0.05) with each other. Enriched fecal sample prevalence was 13.8%, and high shedder prevalence was 3.3%; 38.5% of hides and 10.5% of carcasses were positive for E. coli O157:H7. We used logistic regression to assess animal- and truckload-level variables affecting the probability of carcasses testing positive for E. coli O157:H7. All truckload-level predictors significantly affected the probability of an E. coli O157:H7-positive carcass, including presence of a high shedder within the truckload (odds ratio [OR] = 4.0; confidence interval [CI], 1.6 to 10.1), high (>25%) within-truckload fecal prevalence (OR = 19.3; CI, 4.7 to 79.0), and high (>50%) within-truckload hide prevalence (OR = 7.7; CI, 3.1 to 19.6). The only significant animal-level predictor was having a positive hide (OR = 1.6; CI, 1.0 to 2.6). Our results suggest that preharvest interventions for reducing E. coli O157:H7 contamination of carcasses should focus on truckload (cohort)-level and hide mitigation strategies.
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Affiliation(s)
- M E Jacob
- Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5606, USA
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Bai J, Shi X, Nagaraja TG. A multiplex PCR procedure for the detection of six major virulence genes in Escherichia coli O157:H7. J Microbiol Methods 2010; 82:85-9. [PMID: 20472005 DOI: 10.1016/j.mimet.2010.05.003] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Revised: 05/02/2010] [Accepted: 05/06/2010] [Indexed: 11/25/2022]
Abstract
A multiplex PCR procedure that detects six major virulence genes, fliC, stx1, stx2, eae, rfbE, and hlyA, in Escherichia coli O157:H7 was developed. Analyses of the available sequences of the six major virulence genes and the published primers allowed us to develop the six-gene, multiplex PCR protocol that maintained the specificity of each primer pair. The resulting six bands for fliC, stx1, stx2, eae, rfbE, and hlyA were even and distinct with product sizes of 949, 655, 477, 375, 296, and 199 bp, respectively. The procedure was validated with a total of 221 E. coli strains that included 4 ATCC, 84 cattle, and 57 human E. coli O157:H7 strains as well as 76 non-O157 cattle and human E. coli strains. The results of all 221 strains were similar to the results generated by established multiplex PCR methods that involved two separate reactions to detect five virulence genes (stx1, stx2, eae, fliC, and hlyA). Specificity of the O antigen was indicated by amplification of only O157, and not O25, O26, O55, O78, O103, O111, O127, and O145 E. coli serotypes. Sensitivity tests showed that the procedure amplified genes from a fecal sample spiked with a minimum of 10(4)CFU/g (10 cells/reaction) of E. coli O157. After a 6-h enrichment of E. coli O157-spiked samples, a sensitivity level of 10 CFU/g was achieved.
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Affiliation(s)
- Jianfa Bai
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, 1800 Denison Avenue, Manhattan, KS 66506-5606, United States.
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Zhang J, Lao R, Song S, Yan Z, Fan C. Design of an oligonucleotide-incorporated nonfouling surface and its application in electrochemical DNA sensors for highly sensitive and sequence-specific detection of target DNA. Anal Chem 2009; 80:9029-33. [PMID: 19551931 DOI: 10.1021/ac801424y] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, we report a novel electrochemical DNA sensor based on a nonfouling monolayer structure self-assembled at gold surfaces. Self-assembled monolayers (SAMs) with oligo(ethylene glycol) (OEG)-terminated thiols are known to be highly protein-resistant and effectively repel nonspecific adsorption. We found that a mixed SAM structure incorporating thiolated oligonucleotides and OEG thiols (SH-DNA/OEG) exhibited the similar non-fouling feature. More importantly, it allowed facile electron transfer across the monolayer and thus was fully compatible with electrochemical detection. On the basis of this SH-DNA/OEG platform, we developed a sandwich-type electrochemical sensor for the sequence-specific detection of DNA targets. This sensor was able to detect as little as 1 pM target DNA even in the presence of complicated biological fluids such as human serum. We also employed this sensor to directly detect a polymerase chain reaction (PCR) amplicon from the genomic DNA of Escherichia coli K12, which led to a very low detect limit of 60 fg (approximately 10 copies).
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Affiliation(s)
- Jiong Zhang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
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Liao WC, Ho JAA. Attomole DNA Electrochemical Sensor for the Detection of Escherichia coli O157. Anal Chem 2009; 81:2470-6. [DOI: 10.1021/ac8020517] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Wei-Ching Liao
- BioAnalytical Laboratory, Department of Chemistry, National Tsing Hua University, Hsinchu 30013 Taiwan
| | - Ja-an Annie Ho
- BioAnalytical Laboratory, Department of Chemistry, National Tsing Hua University, Hsinchu 30013 Taiwan
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