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Ohtsuka K, Hoshino K, Kadowaki N, Ohsaka M, Konishi N, Obata H, Kai A, Terajima J, Hara-Kudo Y. Selective media and real-time PCR assays for the effective detection of enterotoxigenic Escherichia coli in vegetables. Lebensm Wiss Technol 2019. [DOI: 10.1016/j.lwt.2019.108409] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Afroj S, Aldahami K, Reddy G, Guard J, Adesiyun A, Samuel T, Abdela W. Simultaneous Detection of Multiple Salmonella Serovars from Milk and Chicken Meat by Real-Time PCR Using Unique Genomic Target Regions. J Food Prot 2017; 80:1944-1957. [PMID: 29058479 DOI: 10.4315/0362-028x.jfp-17-133] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 07/19/2017] [Indexed: 12/29/2022]
Abstract
A novel genomic and plasmid target-based PCR platform was developed for the detection of Salmonella serovars Heidelberg, Dublin, Hadar, Kentucky, and Enteritidis. Unique genome loci were obtained through extensive genome mining of protein databases and comparative genomic analysis of these serovars. Assays targeting Salmonella serovars Hadar, Heidelberg, Kentucky, and Dublin had 100% specificity and sensitivity, whereas those for Salmonella Enteritidis had 97% specificity and 88% sensitivity. The limits of detection for Salmonella serovars Heidelberg, Kentucky, Hadar, Enteritidis, and Dublin were 12, 9, 40, 13, and 5,280 CFU, respectively. A sensitivity assay was also performed by using milk artificially inoculated with pooled Salmonella serovars, yielding a detection limit of 1 to10 CFU/25 mL of milk samples after enrichment. The minimum DNA detected using the multiplexed TaqMan assay was 75.8 fg (1.53 × 101 genomic equivalents [GE]) for Salmonella Heidelberg, 140.8 fg (2.8 × 101 GE) for Salmonella Enteritidis, and 3.48 pg (6.96 × 102 GE) for Salmonella Dublin. PCR efficiencies were 89.8% for Salmonella Heidelberg, 94.5% for Salmonella Enteritidis, and 75.5% for Salmonella Dublin. Four types of 30 pasteurized milk samples were tested negative by culture techniques and with a genus-specific Salmonella invA gene PCR assay. Among 30 chicken samples similarly tested, 12 (40%) were positive by both culture and the invA PCR. Testing of these 12 samples with the serovar-specific PCR assay detected single and mixed contamination with Salmonella Kentucky, Salmonella Enteritidis, and Salmonella Heidelberg. Five unique primers were designed and tested by multiplex conventional PCR in conjunction with the use of the multiplex TaqMan assay with three of the primers. The diagnostic assays developed in this study could be used as tools for routine detection of these five Salmonella serovars and for epidemiological investigations of foodborne disease outbreaks.
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Affiliation(s)
- Sayma Afroj
- Department of Biology and.,Department of Pathobiology, College of Veterinary Medicine, Tuskegee University, Tuskegee, Alabama 36088, USA (ORCID: http://orcid.org/0000-0002-9262-5117 [W.A.]).,Cellular and Molecular Biosciences Program, Auburn University, Auburn, Alabama 36849, USA
| | - Khaled Aldahami
- Department of Pathobiology, College of Veterinary Medicine, Tuskegee University, Tuskegee, Alabama 36088, USA (ORCID: http://orcid.org/0000-0002-9262-5117 [W.A.])
| | - Gopal Reddy
- Department of Pathobiology, College of Veterinary Medicine, Tuskegee University, Tuskegee, Alabama 36088, USA (ORCID: http://orcid.org/0000-0002-9262-5117 [W.A.])
| | - Jean Guard
- U.S. Department of Agriculture, Agricultural Research Service, Athens, Georgia 30602, USA
| | - Abiodun Adesiyun
- School of Veterinary Medicine, Faculty of Medical Sciences, University of the West Indies, St. Augustine, Trinidad and Tobago
| | - Temesgen Samuel
- Department of Pathobiology, College of Veterinary Medicine, Tuskegee University, Tuskegee, Alabama 36088, USA (ORCID: http://orcid.org/0000-0002-9262-5117 [W.A.])
| | - Woubit Abdela
- Department of Pathobiology, College of Veterinary Medicine, Tuskegee University, Tuskegee, Alabama 36088, USA (ORCID: http://orcid.org/0000-0002-9262-5117 [W.A.])
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Pattabiraman V, Parsons MB, Bopp CA. Real-Time TaqMan PCR Assay for the Detection of Heat-Labile and Heat-Stable Enterotoxin Genes in a Geographically Diverse Collection of Enterotoxigenic Escherichia coli Strains and Stool Specimens. Foodborne Pathog Dis 2016; 13:212-20. [PMID: 26859628 DOI: 10.1089/fpd.2015.2064] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) are an important cause of diarrhea in children under the age of 5 years in developing countries and are the leading bacterial agent of traveler's diarrhea in persons traveling to these countries. ETEC strains secrete heat-labile (LT) and/or heat-stable (ST) enterotoxins that induce diarrhea by causing water and electrolyte imbalance. We describe the validation of a real-time TaqMan PCR (RT-PCR) assay to detect LT, ST1a, and ST1b enterotoxin genes in E. coli strains and in stool specimens. We validated LT/ST1b duplex and ST1a single-plex RT-PCR assay using a conventional PCR assay as a gold standard with 188 ETEC strains and 42 non-ETEC strains. We validated LT/ST1b duplex and ST1a single-plex RT-PCR assay in stool specimens (n = 106) using traditional culture as the gold standard. RT- PCR assay sensitivities for LT, ST1a, and ST1b detection in strains were 100%, 100%, and 98%; specificities were 95%, 98%, and 99%, and Pearson correlation coefficient r was 0.9954 between RT-PCR assay and the gold standard. In stool specimens, RT-PCR assay sensitivities for LT, ST1a, and ST1b detection were 97%, 100%, and 97%; and specificities were 99%, 94%, and 97%. Pearson correlation coefficient r was 0.9975 between RT-PCR results in stool specimens and the gold standard. Limits of detection of LT, ST1a, and ST1b by RT-PCR assay were 0.1 to1.0 pg/μL and by conventional PCR assay were 100 to1000 pg/μL. The accuracy, rapidity and sensitivity of this RT-PCR assay is promising for ETEC detection in public health/clinical laboratories and for laboratories in need of an independent method to confirm results of other culture independent diagnostic tests.
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Affiliation(s)
- Vaishnavi Pattabiraman
- National Center for Zoonotic and Emerging Infectious Diseases, Centers for Disease Control and Prevention , Atlanta, Georgia
| | - Michele B Parsons
- National Center for Zoonotic and Emerging Infectious Diseases, Centers for Disease Control and Prevention , Atlanta, Georgia
| | - Cheryl A Bopp
- National Center for Zoonotic and Emerging Infectious Diseases, Centers for Disease Control and Prevention , Atlanta, Georgia
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Letchumanan V, Pusparajah P, Tan LTH, Yin WF, Lee LH, Chan KG. Occurrence and Antibiotic Resistance of Vibrio parahaemolyticus from Shellfish in Selangor, Malaysia. Front Microbiol 2015; 6:1417. [PMID: 26697003 PMCID: PMC4678184 DOI: 10.3389/fmicb.2015.01417] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 11/27/2015] [Indexed: 01/19/2023] Open
Abstract
High consumer demand for shellfish has led to the need for large-scale, reliable shellfish supply through aquaculture or shellfish farming. However, bacterial infections which can spread rapidly among shellfish poses a major threat to this industry. Shellfish farmers therefore often resort to extensive use of antibiotics, both prophylactically and therapeutically, in order to protect their stocks. The extensive use of antibiotics in aquaculture has been postulated to represent a major contributing factor in the rising incidence of antimicrobial resistant pathogenic bacteria in shellfish. This study aimed to investigate the incidence of pathogenic Vibrio parahaemolyticus and determine the antibiotic resistance profile as well as to perform plasmid curing in order to determine the antibiotic resistance mediation. Based on colony morphology, all 450 samples tested were positive for Vibrio sp; however, tox-R assay showed that only 44.4% (200/450) of these were V. parahaemolyticus. Out of these 200 samples, 6.5% (13/200) were trh-positive while none were tdh-positive. Antibiotic resistance was determined for all V. parahaemolyticus identified against 14 commonly used antibiotics and the multiple antibiotic resistance index (MAR) was calculated. The isolates demonstrated high resistance to several antibiotics tested- including second and third-line antibiotics- with 88% resistant to ampicillin, 81% to amikacin,70.5% to kanamycin, 73% to cefotaxime, and 51.5% to ceftazidime. The MAR index ranged from 0.00 to 0.79 with the majority of samples having an index of 0.36 (resistant to five antibiotics). Among the 13 trh-positive strains, almost 70% (9/13) demonstrated resistance to 4 or more antibiotics. Plasmid profiling for all V. parahaemolyticus isolates revealed that 86.5% (173/200) contained plasmids - ranging from 1 to 7 plasmids with DNA band sizes ranging from 1.2 kb to greater than 10 kb. 6/13 of the pathogenic V. pathogenic strains contained plasmid. After plasmid curing, the plasmid containing pathogenic strains isolated in our study have chromosomally mediated ampicillin resistance while the remaining resistance phenotypes are plasmid mediated. Overall, our results indicate that while the incidence of pathogenic V. parahaemolyticus in shellfish in Selangor still appears to be at relatively reassuring levels, antibiotic resistance is a real concern and warrants ongoing surveillance.
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Affiliation(s)
- Vengadesh Letchumanan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya Kuala Lumpur, Malaysia ; Biomedical Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia Bandar Sunway, Malaysia
| | - Priyia Pusparajah
- Biomedical Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia Bandar Sunway, Malaysia
| | - Loh Teng-Hern Tan
- Biomedical Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia Bandar Sunway, Malaysia
| | - Wai-Fong Yin
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya Kuala Lumpur, Malaysia
| | - Learn-Han Lee
- Biomedical Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia Bandar Sunway, Malaysia
| | - Kok-Gan Chan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya Kuala Lumpur, Malaysia
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Yang W, Song X, Wang J, Li Z, Ji M, Li Y. Detection methods for milk pathogenic bacteria by loop-mediated isothermal amplification. Biosci Trends 2015; 8:316-21. [PMID: 25641177 DOI: 10.5582/bst.2014.01118] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Milk is a common food, which is consumed all over the world. It is an important source of calcium. Meanwhile, it provides abundant protein, minerals and vitamins. However, pathogenic bacteria which exist in milk not only causes nutrition loss, but also produces toxins which may cause diarrhea, food poisoning, and even death. In order to control the microbial level of raw milk and eliminate the contamination of materials, this assay applied loop-mediated isothermal amplification to explore a new way to detect enterotoxigenic Escherichia coli (ETEC) in raw milk. The best reaction condition in detecting ETEC from raw milk was confirmed to be: 0.016 μM each of forward outer primer (primer F3) and backward outer primer (primer B3), 0.128 μM each of forward inner primer (primer FIP) and backward inner primer (primer BIP), 0.45 μM deoxy-ribonucleoside triphosphate (dNTPs), 2IU Bst DNA polymerase large fragment and template DNA were incubated at 63°C for 60 min. LAMP was proved to be specific, rapid and sensitive in detecting pathogenic bacteria which exist in milk.
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Letchumanan V, Yin WF, Lee LH, Chan KG. Prevalence and antimicrobial susceptibility of Vibrio parahaemolyticus isolated from retail shrimps in Malaysia. Front Microbiol 2015; 6:33. [PMID: 25688239 PMCID: PMC4311705 DOI: 10.3389/fmicb.2015.00033] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 01/11/2015] [Indexed: 12/21/2022] Open
Abstract
Vibrio parahaemolyticus is a marine and estuarine bacterium that has been the leading cause of foodborne outbreaks which leads to a significant threat to human health worldwide. Consumption of seafood contaminated with V. parahaemolyticus causes acute gastroenteritis in individuals. The bacterium poses two main virulence factor including the thermostable direct hemolysin (tdh) which is a pore-forming protein that contributes to the invasiveness of the bacterium in humans and TDH-related hemolysin (trh), which plays a similar role as tdh in the disease pathogenesis. This study aimed to investigate the antimicrobial resistance V. parahaemolyticus strains in shrimps purchased from wetmarkets and supermarkets. The toxR-based PCR assay indicated that a total of 57.8% (185/320) isolates were positive for V. parahaemolyticus. Only 10% (19/185) toxR-positive isolate exhibit the trh gene and none of the isolates were tested positive for tdh. The MAR index was measured for 14 common antimicrobial agents. The results indicated 98% of the isolates were highly susceptible to imipenem, ampicillin sulbactam (96%), chloramphenicol (95%), trimethoprim-sulfamethoxazole (93%), gentamicin (85%), levofloxacin (83%), and tetracycline (82%). The chloramphenicol (catA2) and kanamycin (aphA-3) resistance genes were detected in the resistant V. parahaemolyticus isolates. Our results demonstrate that shrimps are contaminated with V. parahaemolyticus, some of which carry the trh-gene thus being potential to cause food borne illness. The occurrence of multidrug resistance strains in the environment could be an indication of excessive usage of antibiotics in agriculture and aquaculture fields.
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Affiliation(s)
- Vengadesh Letchumanan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya Kuala Lumpur, Malaysia ; Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia Bandar Sunway, Malaysia
| | - Wai-Fong Yin
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya Kuala Lumpur, Malaysia
| | - Learn-Han Lee
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia Bandar Sunway, Malaysia
| | - Kok-Gan Chan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya Kuala Lumpur, Malaysia
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Draft Whole-Genome Sequences of 10 Serogroup O6 Enterotoxigenic Escherichia coli Strains. GENOME ANNOUNCEMENTS 2014; 2:2/6/e01274-14. [PMID: 25523765 PMCID: PMC4271155 DOI: 10.1128/genomea.01274-14] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Entertotoxigenic Escherichia coli (ETEC) is a major cause of global diarrhea, resulting in approximately 200 million occurrences and 300,000 to 400,000 deaths annually, primarily in children under the age of five. Here, we announce the release of the draft genomes of 10 ETEC isolates belonging to serogroup O6.
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Letchumanan V, Chan KG, Lee LH. Vibrio parahaemolyticus: a review on the pathogenesis, prevalence, and advance molecular identification techniques. Front Microbiol 2014; 5:705. [PMID: 25566219 PMCID: PMC4263241 DOI: 10.3389/fmicb.2014.00705] [Citation(s) in RCA: 280] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 11/27/2014] [Indexed: 12/13/2022] Open
Abstract
Vibrio parahaemolyticus is a Gram-negative halophilic bacterium that is found in estuarine, marine and coastal environments. V. parahaemolyticus is the leading causal agent of human acute gastroenteritis following the consumption of raw, undercooked, or mishandled marine products. In rare cases, V. parahaemolyticus causes wound infection, ear infection or septicaemia in individuals with pre-existing medical conditions. V. parahaemolyticus has two hemolysins virulence factors that are thermostable direct hemolysin (tdh)-a pore-forming protein that contributes to the invasiveness of the bacterium in humans, and TDH-related hemolysin (trh), which plays a similar role as tdh in the disease pathogenesis. In addition, the bacterium is also encodes for adhesions and type III secretion systems (T3SS1 and T3SS2) to ensure its survival in the environment. This review aims at discussing the V. parahaemolyticus growth and characteristics, pathogenesis, prevalence and advances in molecular identification techniques.
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Affiliation(s)
- Vengadesh Letchumanan
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Bandar Sunway, Malaysia ; Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya Kuala Lumpur, Malaysia
| | - Kok-Gan Chan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya Kuala Lumpur, Malaysia
| | - Learn-Han Lee
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Bandar Sunway, Malaysia
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9
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Cupples AM, Xagoraraki I, Rose JB. New Molecular Methods for Detection of Waterborne Pathogens. Environ Microbiol 2010. [DOI: 10.1002/9780470495117.ch3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
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10
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Lee SH, Jung BY, Rayamahji N, Lee HS, Jeon WJ, Choi KS, Kweon CH, Yoo HS. A multiplex real-time PCR for differential detection and quantification of Salmonella spp., Salmonella enterica serovar Typhimurium and Enteritidis in meats. J Vet Sci 2009; 10:43-51. [PMID: 19255523 PMCID: PMC2801102 DOI: 10.4142/jvs.2009.10.1.43] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Salmonella (S.) Typhimurium and S. Enteritidis are the major causative agents of food-borne illnesses worldwide. Currently, a rapid detection system using multiplex real-time polymerase chain reaction (PCR) has been applied for other food-borne pathogens such as Escherichia coli, Staphylococcus aureus and Streptococcus spp. A multiplex real-time PCR was developed for the simultaneous detection of Salmonella spp., especially S. Typhimurium and S. Enteritidis, in beef and pork. For the specific and sensitive multiplex real-time PCR, three representative primers and probes were designed based on sequence data from Genbank. Among the three DNA extraction methods (boiling, alkaline lysis, and QIAamp DNA Mini Kit), the QIAamp DNA Mini Kit was the most sensitive in this study. The optimized multiplex real-time PCR was applied to artificially inoculated beef or pork. The detection sensitivity of the multiplex real-time PCR was increased. The specificity of the multiplex real-time PCR assay, using 128 pure-cultured bacteria including 110 Salmonella isolates and 18 non-Salmonella isolates, was 100%, 100% and 99.1% for Salmonella spp., S. Typhimurium and S. Enteritidis, respectively. The sensitivity was 100%, 100% and 91.7% for Salmonella spp., S. Typhimurium and S. Enteritidis, respectively. The multiplex real-time PCR assay developed in this study could detect up to 0.54 ± 0.09 and 0.65 ± 0.07 log10 CFU/ml for S. Typhimurium and S. Enteritidis for beef, 1.45 ± 0.21 and 1.65 ± 0.07 log10 CFU/ml for S. Typhimurium and S. Enteritidis for pork, respectively, with all conditions optimized. Our results indicated that the multiplex real-time PCR assay developed in this study could sensitively detect Salmonella spp. and specifically differentiate S. Typhimurium from S. Enteritidis in meats.
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Affiliation(s)
- Su Hwa Lee
- National Veterinary Research and Quarantine Service, Anyang 430-824, Korea
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Elizaquível P, Aznar R. A multiplex RTi-PCR reaction for simultaneous detection of Escherichia coli O157:H7, Salmonella spp. and Staphylococcus aureus on fresh, minimally processed vegetables. Food Microbiol 2008; 25:705-13. [PMID: 18541170 DOI: 10.1016/j.fm.2008.03.002] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2007] [Revised: 02/25/2008] [Accepted: 03/01/2008] [Indexed: 11/16/2022]
Abstract
In this work, a new multiplex single-tube real-time PCR approach is presented for the detection of Escherichia coli O157:H7, Salmonella spp. and Staphylococcus aureus, three of the more frequent food-borne bacterial pathogens that are usually investigated in a variety of food matrices. The study includes the design and specificity testing, of a new primer and probe specific for Salmonella spp. Reaction conditions were adjusted for the simultaneous amplification and detection of specific fragments in the beta-glucuronidase (uidA, E. coli) and Thermonulease (nuc, Sta. aureus) genes, and in the replication origin sequence (oriC, Salmonella spp.). Melting-curve analysis using a SYBR Green I RTi-PCR approach showed characteristic T(m) values demonstrating the specific and efficient amplification of the three fragments. Subsequently, a TaqMan RTi-PCR approach was settled, using FAM, NED and VIC fluorescently labelled specific probes for an automated detection. It was equally sensitive than uniplex RTi-PCR reactions in Sta. aureus and E. coli O157:H7, using same amounts of purified DNA, and allowed detection of 10 genome equivalents in the presence of 10(2) or 10(4) genome equivalents of the other two pathogens. Finally, it was tested in artificially inoculated fresh, minimally processed vegetables, revealing a sensitivity of 10(3)CFUg(-1) each of these pathogens in direct detection, following DNA extraction with DNeasy Tissue Kit (Qiagen). The multiplex RTi-PCR developed scored the sensitivity recognised for PCR in food and it allows a high-throughput and automation, thus it is promising as a rapid and cost-effective test for the food industry.
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Affiliation(s)
- Patricia Elizaquível
- Departamento de Microbiología y Ecologia, Universitat de València, Burjassot E-46100, Valencia, Spain
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Foley SL, Zhao S, Walker RD. Comparison of molecular typing methods for the differentiation of Salmonella foodborne pathogens. Foodborne Pathog Dis 2007; 4:253-76. [PMID: 17883310 DOI: 10.1089/fpd.2007.0085] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Bacteria belonging to the genus Salmonella are among the leading causes of foodborne disease of bacterial etiology. These bacteria are also widely disseminated throughout the animal kingdom. The ability to identify the food source from which a human pathogen originated would be of great value in reducing the incidence of foodborne disease and the extent of disease outbreaks due to Salmonella. To date, efforts to identify the origin of these pathogens have centered on phenotypic and genotypic characterization of Salmonella isolates. This review focuses molecular or genotypic techniques that are currently being used for typing, and examines their strengths and weaknesses for determining the source of Salmonella foodborne infections.
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Affiliation(s)
- Steven L Foley
- National Farm Medicine Center, Marshfield Clinic Research Foundation, Marshfield, Wisconsin 54449, USA.
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Lucas LJ, Chesler JN, Yoon JY. Lab-on-a-chip immunoassay for multiple antibodies using microsphere light scattering and quantum dot emission. Biosens Bioelectron 2007; 23:675-81. [PMID: 17869502 DOI: 10.1016/j.bios.2007.08.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 08/01/2007] [Accepted: 08/03/2007] [Indexed: 11/21/2022]
Abstract
Double detection of microsphere light scattering and quantum dot emission was demonstrated for lab-on-a-chip immunoassay without using stationary support. We conjugated quantum dots (QDs) onto microspheres to enable multiplex assays as well as to enhance the limit of detection (LOD). We named this configuration "nano-on-micro" or "NOM". Upon radiation with UV light (380nm), a stronger light scattering signal is observed with NOMs than QDs or microspheres alone. Additionally, NOMs are easier to handle than QDs. Since QDs also provide fluorescent emission, we are able to utilize an increase in light scattering for detecting antigen-antibody reaction and a decrease in QD emission to identify which antibody (or antigen) is present. Two types of NOM combinations were used. One batch of microspheres was coated with QDs emitting at 655 nm and mouse IgG (mIgG); the other with QDs emitting at 605 nm and bovine serum albumin (BSA). A mixture of these two NOMs was used to identify either anti-mIgG or anti-BSA. NOM particles and target solutions were mixed in a microfluidic device (using highly carboxylated microspheres as previously demonstrated by our group) and on-chip detection was performed using proximity optical fibers. Forward light scattering at 380 nm was collected. With the positive target, the scattering signal was increased. The LOD was as low as 50 ng ml(-1) (330 pM) with p<0.05. Fluorescent emission (655 or 605 nm) was simultaneously collected. With the positive target, the emission signal was attenuated. Therefore, we were able to detect two different antibodies simultaneously with two different detection protocols. We believe this NOM bioassay has the ability to screen for and detect multiple antibodies with minimal sample processing and handling (one-step lab-on-a-chip immunoassay).
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Affiliation(s)
- Lonnie J Lucas
- Department of Agricultural and Biosystems Engineering, The University of Arizona, Tucson, AZ 85721-0038, USA
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PERRY LYNDA, HEARD PRECIAUS, KANE MICHAEL, KIM HANYOUP, SAVIKHIN SERGEI, DOMÍNGUEZ WILFREDO, APPLEGATE BRUCE. APPLICATION OF MULTIPLEX POLYMERASE CHAIN REACTION TO THE DETECTION OF PATHOGENS IN FOOD. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1745-4581.2007.00083.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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15
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Deepak SA, Kottapalli KR, Rakwal R, Oros G, Rangappa KS, Iwahashi H, Masuo Y, Agrawal GK. Real-Time PCR: Revolutionizing Detection and Expression Analysis of Genes. Curr Genomics 2007; 8:234-51. [PMID: 18645596 PMCID: PMC2430684 DOI: 10.2174/138920207781386960] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Revised: 02/27/2007] [Accepted: 03/02/2007] [Indexed: 02/06/2023] Open
Abstract
Invention of polymerase chain reaction (PCR) technology by Kary Mullis in 1984 gave birth to real-time PCR. Real-time PCR - detection and expression analysis of gene(s) in real-time - has revolutionized the 21(st) century biological science due to its tremendous application in quantitative genotyping, genetic variation of inter and intra organisms, early diagnosis of disease, forensic, to name a few. We comprehensively review various aspects of real-time PCR, including technological refinement and application in all scientific fields ranging from medical to environmental issues, and to plant.
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Affiliation(s)
- SA Deepak
- Department of Studies in Applied Botany and Biotechnology, University of Mysore, Manasagangotri, Mysore 570006,
India
| | - KR Kottapalli
- Plant Genome Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba 305-
8602, Ibaraki, Japan
| | - R Rakwal
- Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science
and Technology (AIST), Tsukuba West, 16-1 Onogawa, Tsukuba 305-8569, Ibaraki, Japan
- Research Laboratory for
Agricultural Biotechnology and Biochemistry (RLABB), GPO Box 8207, Kathmandu, Nepal
| | - G Oros
- Plant Protection Institute,
Hungarian Academy of Sciences, Budapest, Hungary
| | - KS Rangappa
- Department of Studies in Chemistry, University of Mysore,
Manasagangotri, Mysore 570006, India
| | - H Iwahashi
- Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science
and Technology (AIST), Tsukuba West, 16-1 Onogawa, Tsukuba 305-8569, Ibaraki, Japan
| | - Y Masuo
- Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science
and Technology (AIST), Tsukuba West, 16-1 Onogawa, Tsukuba 305-8569, Ibaraki, Japan
| | - GK Agrawal
- Research Laboratory for
Agricultural Biotechnology and Biochemistry (RLABB), GPO Box 8207, Kathmandu, Nepal
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