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Kadyan S, Kumar N, Lawaniya R, Sharma PK, Arora B, Tehri N. Rapid and miniaturized method for detection of hygiene indicators,Escherichia coliand coliforms,in dairy products. J Food Saf 2020. [DOI: 10.1111/jfs.12839] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Saurabh Kadyan
- National Referral Centre for Milk Quality and Safety, Dairy Microbiology Division ICAR‐National Dairy Research Institute Karnal Haryana India
| | - Naresh Kumar
- National Referral Centre for Milk Quality and Safety, Dairy Microbiology Division ICAR‐National Dairy Research Institute Karnal Haryana India
| | - Ramakant Lawaniya
- National Referral Centre for Milk Quality and Safety, Dairy Microbiology Division ICAR‐National Dairy Research Institute Karnal Haryana India
| | - Pradeep Kumar Sharma
- National Referral Centre for Milk Quality and Safety, Dairy Microbiology Division ICAR‐National Dairy Research Institute Karnal Haryana India
| | - Bhawna Arora
- National Referral Centre for Milk Quality and Safety, Dairy Microbiology Division ICAR‐National Dairy Research Institute Karnal Haryana India
| | - Nimisha Tehri
- National Referral Centre for Milk Quality and Safety, Dairy Microbiology Division ICAR‐National Dairy Research Institute Karnal Haryana India
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Development and application of a real-time polymerase chain reaction method for quantification of Escherichia coli in oysters (Crassostrea gigas). Food Microbiol 2019; 77:85-92. [DOI: 10.1016/j.fm.2018.08.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 07/30/2018] [Accepted: 08/31/2018] [Indexed: 11/17/2022]
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3
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The species accuracy of the Most Probable Number (MPN) European Union reference method for enumeration of Escherichia coli in marine bivalves. J Microbiol Methods 2016; 131:73-77. [PMID: 27746195 DOI: 10.1016/j.mimet.2016.10.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 10/12/2016] [Accepted: 10/12/2016] [Indexed: 11/22/2022]
Abstract
Continuous European Union programmes with specified methods for enumeration of Escherichia coli in bivalves for human consumption are currently running. The objective of this research was to examine the species accuracy of the five times three tube Most Probable Number (MPN) EU reference method used for detection of E. coli in marine bivalves. Among 549 samples of bivalves harvested from Norwegian localities during 2014 and 2015, a total number of 200 bacterial isolates were prepared from randomly selected culture-positive bivalves. These presumptive E. coli isolates were characterized biochemically by the Analytical Profile Index (API) 20E, as well as by Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS). The majority of isolates (90%) were identified as E. coli, by both API 20E and MALDI-TOF MS. Ten isolates (5%) were identified as Klebsiella pneumoniae, while one isolate was identified as K. oxytoca by both methods, whereas three isolates were identified as Acinetobacter baumannii, Citrobacter braakii, and Enterobacter cloacae, respectively. The identification of the remaining six isolates were not in compliance between the two methods.
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Molina F, López-Acedo E, Tabla R, Roa I, Gómez A, Rebollo JE. Improved detection of Escherichia coli and coliform bacteria by multiplex PCR. BMC Biotechnol 2015; 15:48. [PMID: 26040540 PMCID: PMC4453288 DOI: 10.1186/s12896-015-0168-2] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 05/17/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The presence of coliform bacteria is routinely assessed to establish the microbiological safety of water supplies and raw or processed foods. Coliforms are a group of lactose-fermenting Enterobacteriaceae, which most likely acquired the lacZ gene by horizontal transfer and therefore constitute a polyphyletic group. Among this group of bacteria is Escherichia coli, the pathogen that is most frequently associated with foodborne disease outbreaks and is often identified by β-glucuronidase enzymatic activity or by the redundant detection of uidA by PCR. Because a significant fraction of essential E. coli genes are preserved throughout the bacterial kingdom, alternative oligonucleotide primers for specific E. coli detection are not easily identified. RESULTS In this manuscript, two strategies were used to design oligonucleotide primers with differing levels of specificity for the simultaneous detection of total coliforms and E. coli by multiplex PCR. A consensus sequence of lacZ and the orphan gene yaiO were chosen as targets for amplification, yielding 234 bp and 115 bp PCR products, respectively. CONCLUSIONS The assay designed in this work demonstrated superior detection ability when tested with lab collection and dairy isolated lactose-fermenting strains. While lacZ amplicons were found in a wide range of coliforms, yaiO amplification was highly specific for E. coli. Additionally, yaiO detection is non-redundant with enzymatic methods.
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Affiliation(s)
- Felipe Molina
- Área de Genética, Departamento de Bioquímica y Biologia Molecular y Genética, Universidad de Extremadura, Badajoz, Spain.
| | - Elena López-Acedo
- Área de Genética, Departamento de Bioquímica y Biologia Molecular y Genética, Universidad de Extremadura, Badajoz, Spain.
| | - Rafael Tabla
- Dairy products, Technological institute of Food and Agriculture, Badajoz, Spain.
| | - Isidro Roa
- Dairy products, Technological institute of Food and Agriculture, Badajoz, Spain.
| | - Antonia Gómez
- Dairy products, Technological institute of Food and Agriculture, Badajoz, Spain.
| | - José E Rebollo
- Área de Genética, Departamento de Bioquímica y Biologia Molecular y Genética, Universidad de Extremadura, Badajoz, Spain.
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Briciu-Burghina C, Heery B, Regan F. Continuous fluorometric method for measuring β-glucuronidase activity: comparative analysis of three fluorogenic substrates. Analyst 2015. [DOI: 10.1039/c5an01021g] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
A new continuous fluorometric method for measuring GUS activity shows a superior analytical performance to the established discontinuous method.
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Affiliation(s)
- Ciprian Briciu-Burghina
- Marine and Environmental Sensing Technology Hub (MESTECH)
- National Centre for Sensor Research (NCSR)
- School of Chemical Sciences
- Dublin City University
- Dublin
| | - Brendan Heery
- Marine and Environmental Sensing Technology Hub (MESTECH)
- National Centre for Sensor Research (NCSR)
- School of Chemical Sciences
- Dublin City University
- Dublin
| | - Fiona Regan
- Marine and Environmental Sensing Technology Hub (MESTECH)
- National Centre for Sensor Research (NCSR)
- School of Chemical Sciences
- Dublin City University
- Dublin
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Sangadkit W, Rattanabumrung O, Supanivatin P, Thipayarat A. Practical coliforms and Escherichia coli detection and enumeration for industrial food samples using low-cost digital microscopy. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/j.proeng.2012.01.1246] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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McLain JE, Rock CM, Lohse K, Walworth J. False-positive identification ofEscherichia coliin treated municipal wastewater and wastewater-irrigated soils. Can J Microbiol 2011; 57:775-84. [DOI: 10.1139/w11-070] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The increasing use of treated wastewater for irrigation heightens the importance of accurate monitoring of water quality. Chromogenic media, because they are easy to use and provide rapid results, are often used for detection of Escherichia coli in environmental samples, but unique levels of organic and inorganic compounds alter the chemistry of treated wastewater, potentially hindering the accurate performance of chromogenic media. We used MI agar and molecular confirmatory methods to assess false-positive identification of E. coli in treated wastewater samples collected from municipal utilities, an irrigation holding pond, irrigated soils, and in samples collected from storm flows destined for groundwater recharge. False-positive rates in storm flows (4.0%) agreed closely with USEPA technical literature but were higher in samples from the pond, soils, and treatment facilities (33.3%, 38.0%, and 48.8%, respectively). Sequencing of false-positive isolates confirmed that most were, like E. coli, of the family Enterobacteriaceae, and many of the false-positive isolates were reported to produce the β-d-glucuronidase enzyme targeted by MI agar. False-positive identification rates were inversely related to air temperature, suggesting that seasonal variations in water quality influence E. coli identification. Knowledge of factors contributing to failure of chromogenic media will lead to manufacturer enhancements in media quality and performance and will ultimately increase the accuracy of future water quality monitoring programs.
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Affiliation(s)
- Jean E.T. McLain
- USDA–ARS, US Arid-Land Agricultural Research Center, 21881 North Cardon Lane, Maricopa, AZ 85138, USA
| | - Channah M. Rock
- Department of Soil, Water and Environmental Sciences, University of Arizona, Tucson, AZ 85721, USA
| | - Kathleen Lohse
- Department of Biological Sciences, Idaho State University, Pocatello, ID 83209, USA
| | - James Walworth
- Department of Soil, Water and Environmental Sciences, University of Arizona, Tucson, AZ 85721, USA
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Takahashi H, Kimura B, Tanaka Y, Shinozaki J, Suda T, Fujii T. Real-time PCR and enrichment culture for sensitive detection and enumeration of Escherichia coli. J Microbiol Methods 2009; 79:124-7. [PMID: 19679150 DOI: 10.1016/j.mimet.2009.08.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 07/29/2009] [Accepted: 08/03/2009] [Indexed: 10/20/2022]
Abstract
Rapid enumeration of Escherichia coli strains by quantitative real-time PCR targeting the uidA gene was developed and confirmed for minced beef, tuna and raw oyster. Higher sensitivity (1 CFU/g of E. coli in all three food samples) was obtained by incubating for 7 h in TSB. Colony-directed E. coli specific TaqMan PCR assay could effectively distinguish colonies grown on various selective media within 1.5-h. Inspection of E. coli in food testing laboratories is important, and our rapid E. coli detection strategy will contribute to quality control in food industries.
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Affiliation(s)
- Hajime Takahashi
- Department of Food Science and Technology, Faculty of Marine Science, Tokyo University of Marine Science and Technology, 5-7 Konan 4, Minato, Tokyo 108-8477, Japan
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Thampuran N, Surendraraj A, Surendran PK. Prevalence and characterization of typical and atypical Escherichia coli from fish sold at retail in Cochin, India. J Food Prot 2005; 68:2208-11. [PMID: 16245731 DOI: 10.4315/0362-028x-68.10.2208] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Escherichia coli is a common contaminant of seafood in the tropics and is often encountered in high numbers. The count of E. coli as well as verotoxigenic E. coli O157:H7 was estimated in 414 finfish samples composed of 23 species of fresh fish from retail markets and frozen fish from cold storage outlets in and around Cochin, India. A total of 484 presumptive E. coli were isolated, and their indole-methyl red-Voges-Proskauer-citrate (IMViC) pattern was determined. These strains were also tested for labile toxin production by a reverse passive latex agglutination method and checked for E. coli serotype O157 by latex agglutination with O157-specific antisera. Certain biochemical marker tests, such as methylumbelliferyl-beta-glucuronide (MUG), sorbitol fermentation, decarboxylase reactions, and hemolysis, which are useful for screening pathogenic E. coli, were also carried out. Results showed that 81.4% of the E. coli isolates were sorbitol positive. Among this group, 82% were MUG positive, and 14.46% of the total E. coli isolates showed human blood hemolysis. None of the isolates were positive for agglutination with E. coli O157 antisera nor did any produce heat-labile enterotoxin. This study indicates that typical E. coli O157 or labile toxin-producing E. coli is absent in the fish and fishery environments of Cochin (India). However, the presence of MUG and sorbitol-negative strains that are also hemolytic indicates the existence of aberrant strains, which require further investigation.
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Affiliation(s)
- Nirmala Thampuran
- Central Institute of Fisheries Technology, Matsyapuri P.O., Cochin-682 029, India.
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Affiliation(s)
- Raz Jelinek
- Department of Chemistry and Staedler Minerva Center for Mesoscopic Macromolecular Engineering, Ben Gurion University of the Negev, Beersheva 84105, Israel.
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González R, Tamagnini L, Olmos P, de Sousa G. Evaluation of a chromogenic medium for total coliforms and Escherichia coli determination in ready-to-eat foods. Food Microbiol 2003. [DOI: 10.1016/s0740-0020(02)00178-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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12
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Ertl P, Wagner M, Corton E, Mikkelsen SR. Rapid identification of viable Escherichia coli subspecies with an electrochemical screen-printed biosensor array. Biosens Bioelectron 2003; 18:907-16. [PMID: 12713914 DOI: 10.1016/s0956-5663(02)00206-3] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Rapid identification of Escherichia coli strains is an important diagnostic goal in applied medicine as well as the environmental and food sciences. This paper reports an electrochemical, screen-printed biosensor array, where selective recognition is accomplished using lectins that recognize and bind to cell-surface lipopolysaccharides and coulometric transduction exploits non-native external oxidants to monitor respiratory cycle activity in lectin-bound cells. Ten different lectins were separately immobilized onto porous membranes that feature activated surfaces (ImmunodyneABC). Modified membranes were exposed to untreated E. coli cultures for 30 min, rinsed, and layered over the individual screen-printed carbon electrodes of the sensor array. The membranes were were incubated 5 min in a reagent solution that contained the oxidants menadione and ferricyanide as well as the respiratory substrates succinate and formate. Electrochemical oxidation of ferrocyanide for 2 min provided chronocoulometric data related to the quantities of bound cells. These screen-printed sensor arrays were used in conjunction with factor analysis for the rapid identification of four E. coli subspecies (E. coli B, E. coli Neotype, E. coli JM105 and E. coli HB101). Systematic examination of lectin-binding patterns showed that these four E. coli subspecies are readily distinguished using only five essential lectins.
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Affiliation(s)
- Peter Ertl
- Department of Chemistry, University of Waterloo, Ont., Waterloo, Canada N2L 3G1
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Rompré A, Servais P, Baudart J, de-Roubin MR, Laurent P. Detection and enumeration of coliforms in drinking water: current methods and emerging approaches. J Microbiol Methods 2002; 49:31-54. [PMID: 11777581 DOI: 10.1016/s0167-7012(01)00351-7] [Citation(s) in RCA: 297] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The coliform group has been used extensively as an indicator of water quality and has historically led to the public health protection concept. The aim of this review is to examine methods currently in use or which can be proposed for the monitoring of coliforms in drinking water. Actually, the need for more rapid, sensitive and specific tests is essential in the water industry. Routine and widely accepted techniques are discussed, as are methods which have emerged from recent research developments.Approved traditional methods for coliform detection include the multiple-tube fermentation (MTF) technique and the membrane filter (MF) technique using different specific media and incubation conditions. These methods have limitations, however, such as duration of incubation, antagonistic organism interference, lack of specificity and poor detection of slow-growing or viable but non-culturable (VBNC) microorganisms. Nowadays, the simple and inexpensive membrane filter technique is the most widely used method for routine enumeration of coliforms in drinking water.The detection of coliforms based on specific enzymatic activity has improved the sensitivity of these methods. The enzymes beta-D galactosidase and beta-D glucuronidase are widely used for the detection and enumeration of total coliforms and Escherichia coli, respectively. Many chromogenic and fluorogenic substrates exist for the specific detection of these enzymatic activities, and various commercial tests based on these substrates are available. Numerous comparisons have shown these tests may be a suitable alternative to the classical techniques. They are, however, more expensive, and the incubation time, even though reduced, remains too long for same-day results. More sophisticated analytical tools such as solid phase cytometry can be employed to decrease the time needed for the detection of bacterial enzymatic activities, with a low detection threshold. Detection of coliforms by molecular methods is also proposed, as these methods allow for very specific and rapid detection without the need for a cultivation step. Three molecular-based methods are evaluated here: the immunological, polymerase chain reaction (PCR) and in-situ hybridization (ISH) techniques. In the immunological approach, various antibodies against coliform bacteria have been produced, but the application of this technique often showed low antibody specificity. PCR can be used to detect coliform bacteria by means of signal amplification: DNA sequence coding for the lacZ gene (beta-galactosidase gene) and the uidA gene (beta-D glucuronidase gene) has been used to detect total coliforms and E. coli, respectively. However, quantification with PCR is still lacking in precision and necessitates extensive laboratory work. The FISH technique involves the use of oligonucleotide probes to detect complementary sequences inside specific cells. Oligonucleotide probes designed specifically for regions of the 16S RNA molecules of Enterobacteriaceae can be used for microbiological quality control of drinking water samples. FISH should be an interesting viable alternative to the conventional culture methods for the detection of coliforms in drinking water, as it provides quantitative data in a fairly short period of time (6 to 8 h), but still requires research effort. This review shows that even though many innovative bacterial detection methods have been developed, few have the potential for becoming a standardized method for the detection of coliforms in drinking water samples.
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Affiliation(s)
- Annie Rompré
- NSERC Industrial Chair on Drinking Water, Civil, Geological and Mining Engineering, Ecole Polytechnique of Montreal, PO Box 6079, succ. Centre Ville, H3C 3A7, Montreal, Quebec, Canada
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McFeters GA, Broadaway SC, Pyle BH, Pickett M, Egozy Y. Comparative performance of Colisure. ACTA ACUST UNITED AC 1997. [DOI: 10.1002/j.1551-8833.1997.tb08294.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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15
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Vilamú M, Vives-Rego J. Fluorogenic assay for immediate presumptive detection of Escherichia coli in urine. Lett Appl Microbiol 1994. [DOI: 10.1111/j.1472-765x.1994.tb00464.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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16
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Frampton EW, Restaino L. Methods for Escherichia coli identification in food, water and clinical samples based on beta-glucuronidase detection. THE JOURNAL OF APPLIED BACTERIOLOGY 1993; 74:223-33. [PMID: 8468256 DOI: 10.1111/j.1365-2672.1993.tb03019.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- E W Frampton
- Department of Biological Sciences, Northern Illinois University, DeKalb 60115
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17
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Covert TC, Rice EW, Johnson SA, Berman D, Johnson CH, Mason PJ. Comparing Defined-Substrate Coliform Tests for the Detection of Escherichia coli in Water. ACTA ACUST UNITED AC 1992. [DOI: 10.1002/j.1551-8833.1992.tb07359.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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18
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Manafi M, Kneifel W, Bascomb S. Fluorogenic and chromogenic substrates used in bacterial diagnostics. Microbiol Rev 1991; 55:335-48. [PMID: 1943991 PMCID: PMC372823 DOI: 10.1128/mr.55.3.335-348.1991] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Methods based on the application of chromogenic and fluorogenic substrates enable specific and rapid detection of a variety of bacterial enzymatic activities. By using these techniques, enzymatic reactions can be examined simultaneously or individually, either directly on the isolation plate or in cell suspensions. For this purpose, various testing principles and test kits for clinical and food microbiology have been introduced successfully during the last few years. In this paper we present a survey of different enzymes of microbial origin that are utilized for microbiological identification and differentiation and the corresponding methods. Particular emphasis is given to the examination of Escherichia coli and the description of the different techniques as used in routine analysis.
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Affiliation(s)
- M Manafi
- Hygiene Institute, University of Vienna, Austria
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19
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Feng P, Lum R, Chang GW. Identification of uidA gene sequences in beta-D-glucuronidase-negative Escherichia coli. Appl Environ Microbiol 1991; 57:320-3. [PMID: 2036018 PMCID: PMC182706 DOI: 10.1128/aem.57.1.320-323.1991] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
A probe specific for the uidA gene of Escherichia coli hybridized with 112 of 116 E. coli isolates examined, including 31 beta-D-glucuronidase-negative and 12 enterohemorrhagic E. coli serotype O157:H7 isolates. Southern hybridizations confirmed the presence of a 900-bp HinfI fragment from the uidA gene in all isolates examined, suggesting that uidA gene sequences are present in most E. coli.
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Affiliation(s)
- P Feng
- Division of Microbiology, Food and Drug Administration, Washington, D.C. 20204
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Carmen Balebona M, Moriñigo MA, Cornax R, Borrego JJ, Torregrossa VM, Gauthier MJ. Modified most-probable-number technique for the specific determination of Escherichia coli from environmental samples using a fluorogenic method. J Microbiol Methods 1990. [DOI: 10.1016/0167-7012(90)90036-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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21
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Husson MO, Mielcarek C, Izard D, Leclerc H. Alkaline phosphatase capture test for the rapid identification of Escherichia coli and Shigella species based on a specific monoclonal antibody. J Clin Microbiol 1989; 27:1518-21. [PMID: 2671016 PMCID: PMC267607 DOI: 10.1128/jcm.27.7.1518-1521.1989] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
A specific monoclonal antibody for Escherichia coli and Shigella sp. alkaline phosphatase was used in an immunocapture assay and allowed identification of E. coli either in culture isolates or directly in clinical specimens. The assay was easy and required only four steps: (i) alkaline phosphatase was released within 10 min by using a gentle lysis procedure, (ii) cell lysates were transferred to antibody-coated tubes for 45 min, (iii) p-nitrophenyl phosphate substrate was added, and (iv) alkaline phosphatase activity was detected in a microsample spectrophotometer at 410 nm. This immunocapture assay was highly specific: only one false-positive reaction was observed with a Klebsiella pneumoniae lysate among the 205 non-E. coli strains tested. The assay was sensitive, detecting 10(7) CFU/ml from culture isolates or 10(5) CFU/ml from urine specimens which had first been grown in phosphate-limiting medium for 2 h. At these bacterial concentrations, the percentages of detected E. coli were high: 91% for blood cultures, 95.4% for culture isolates, and 96.8% for urine specimens.
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Affiliation(s)
- M O Husson
- Laboratoire de Bactériologie, Faculté de Médecine, Lille, France
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Chang GW, Brill J, Lum R. Proportion of beta-D-glucuronidase-negative Escherichia coli in human fecal samples. Appl Environ Microbiol 1989; 55:335-9. [PMID: 2655534 PMCID: PMC184111 DOI: 10.1128/aem.55.2.335-339.1989] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Convenient assays and reports that almost all clinical isolates of Escherichia coli produce beta-D-glucuronidase (GUR) have led to great interest in the use of the enzyme for the rapid detection of the bacterium in water, food, and environmental samples. In these materials, E. coli serves as an indicator of possible fecal contamination. Therefore, it was crucial to examine the proportion of GUR-negative E. coli in human fecal samples. The bacterium was isolated from 35 samples, and a mean of 34% and a median of 15% were found to be GUR negative in lauryl sulfate tryptose broth with 4-methylumbelliferyl-beta-D-glucuronide. E. coli from three samples were temperature dependent for GUR production: very weakly positive at 37 degrees C but strongly positive at 44.5 degrees C. These results remind us of differences between fecal and clinical E. coli populations, of diversity in GUR regulation and expression in natural populations of E. coli, and of the need for caution in using GUR for the detection of fecal E. coli.
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Affiliation(s)
- G W Chang
- Department of Nutritional Sciences, University of California, Berkeley 94720
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Holt SM, Hartman PA, Kaspar CW. Enzyme-capture assay for rapid detection of Escherichia coli in oysters. Appl Environ Microbiol 1989; 55:229-32. [PMID: 2650619 PMCID: PMC184083 DOI: 10.1128/aem.55.1.229-232.1989] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Enzyme-capture assays (ECAs) for Escherichia coli beta-D-glucuronidase (GUD) were performed directly from 24-h gas-positive lauryl tryptose broth (LTB) fermentation tubes that had been inoculated with oyster homogenate seeded with E. coli. The LTB-ECA method yielded results in 1 day that were equivalent to those obtained in 2 days by an LTB and EC-4-methylumbelliferyl-beta-D-glucuronide (EC-MUG) method. Overall, 62 of 64 (97%) positive EC-MUG broths from which E. coli was isolated were correctly identified by ECA. Of 61 LTB tubes identified as GUD negative by ECA, 59 were confirmed to be free of E. coli by using EC-MUG; thus, the false-negative rate was approximately 3%. Polyclonal antibodies prepared against E. coli GUD reacted only with GUDs of E. coli, Escherichia vulneris, and Shigella sonnei. The antibodies did not react with GUDs from Flavobacterium spp., Staphylococcus spp., Yersinia enterocolitica, shellfish, or bovine liver. The GUD ECA test, when used in conjunction with the most-probable-number technique, was a rapid method for E. coli enumeration in oysters.
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Affiliation(s)
- S M Holt
- Department of Microbiology, Iowa State University, Ames 50011
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