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Froböse NJ, Olaru ID, Schneider JS, Zhang W, Mellmann A, Schuler F, Grebe T, Schaumburg F. Does pre-incubation in selective-enrichment media improve the detection of diarrheagenic Escherichia coli using the RIDA®GENE PCR? Int J Med Microbiol 2023; 313:151575. [PMID: 36736015 DOI: 10.1016/j.ijmm.2023.151575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 01/13/2023] [Accepted: 01/23/2023] [Indexed: 02/01/2023] Open
Abstract
We aimed to investigate whether a selective pre-PCR enrichment step improves test performance of RIDA®GENE EHEC/EPEC to detect diarrheagenic Escherichia coli from stool samples. Each of the 250 stool samples was analyzed for the presence of stx1/2 and eae both with and without pre-PCR enrichment in selective broth. In comparison to a reference method, sensitivities for stx1/2 and eae with and without pre-PCR enrichment were 84% (95%CI 70-93) and 89% (stx1/2, 95%CI 76-96), and 71% (95%CI 58-81) and 72% (eae, 95%CI 60-82), respectively. Specificity exceeded 97% for both methods and target genes. In summary, pre-PCR broth enrichment did not improve test performance.
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Affiliation(s)
- Neele J Froböse
- Institute of Medical Microbiology, University of Münster, Domagkstr 10, 48149 Münster, Germany
| | - Ioana D Olaru
- Institute of Medical Microbiology, University of Münster, Domagkstr 10, 48149 Münster, Germany.
| | - Julia Sophie Schneider
- Institute of Hygiene and National Consulting Laboratory for hemolytic uremic syndrome (HUS), University of Münster, Robert-Koch-Str 41, 48149 Münster, Germany
| | - Wenlan Zhang
- Institute of Hygiene and National Consulting Laboratory for hemolytic uremic syndrome (HUS), University of Münster, Robert-Koch-Str 41, 48149 Münster, Germany
| | - Alexander Mellmann
- Institute of Hygiene and National Consulting Laboratory for hemolytic uremic syndrome (HUS), University of Münster, Robert-Koch-Str 41, 48149 Münster, Germany
| | - Franziska Schuler
- Institute of Medical Microbiology, University of Münster, Domagkstr 10, 48149 Münster, Germany
| | - Tobias Grebe
- Institute of Medical Microbiology, University of Münster, Domagkstr 10, 48149 Münster, Germany
| | - Frieder Schaumburg
- Institute of Medical Microbiology, University of Münster, Domagkstr 10, 48149 Münster, Germany
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Rasamsetti S, Berrang ME, Cox NA, Shariat NW. Assessing Salmonella Prevalence and Complexity Through Processing Using Different Culture Methods. Poult Sci 2022; 101:101949. [PMID: 35688029 PMCID: PMC9189229 DOI: 10.1016/j.psj.2022.101949] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/18/2022] [Accepted: 04/22/2022] [Indexed: 11/16/2022] Open
Abstract
Conventional Salmonella surveillance requires a week for isolation, confirmation, and subsequent serotyping. We previously showed that this could be reduced by 24 h by combining the pre-enrichment and enrichment steps into a single selective pre-enrichment step and was tested on directly after picking. The goal of this study was 2-fold: 1) to evaluate the use of selective pre-enrichment through each step of processing, including postintervention when the Salmonella load is reduced, and 2) to assess any changes in serovar populations in Salmonella positive samples. Duplicate carcass drip samples, each representative of 500 broiler carcasses, were collected by catching processing water drip under moving carcass shackle lines in each of three commercial broiler slaughter plants. Samples were collected post-pick, post-inside-outside bird wash (IOBW), and post-chill; duplicate wing rinses were performed pre- and post-antimicrobial parts dip. Each processing plant was sampled 6 times for a total of 180 samples collected. The number of Salmonella positives identified with selective pre-enrichment conditions (48/180) was similar to traditional selective enrichment culture conditions (52/180), showed good concordance in recovery rate between the 2 culture methods (Fisher's exact test, P = 0.72). We also found that the incidence of Salmonella reduced dramatically after antimicrobial intervention (post-pick 66.7% vs. post chill 8.3%). When serovar populations were evaluated in Salmonella positive samples using CRISPR-SeroSeq, we detected four different Salmonella serovars, Kentucky, Infantis, Schwarzengrund, and Typhimurium, and their incidence rose between post-pick and post-IOBW. The relative abundance of Infantis within individual samples increased between post-pick and post-IOBW while the relative abundance of the other 3 serovars decreased. These results suggest that a selective pre-enrichment step reduces the time required for Salmonella isolation without negatively affecting detection and serovar profiles in culture positive samples were not altered between culture conditions used.
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3
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Development of a real-time PCR assay with an internal amplification control for the detection of spoilage fungi in fruit preparations. Food Control 2022. [DOI: 10.1016/j.foodcont.2021.108783] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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4
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Manage DP, Lauzon J, Pilarski LM, Pilarski PM, McMullen LM. Comparison of a Miniaturized Cassette PCR System with a Commercially Available Platform for Detecting Escherichia coli in Beef Carcass Swabs. MICROMACHINES 2021; 12:mi12080959. [PMID: 34442581 PMCID: PMC8398369 DOI: 10.3390/mi12080959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 08/07/2021] [Accepted: 08/08/2021] [Indexed: 12/05/2022]
Abstract
Detection sensitivity of cassette PCR was compared with a commercial BAX® PCR system for detection of eae and stx genes in Escherichia coli from 806 beef carcass swabs. Cassette PCR detects multiple genetic markers on multiple samples using PCR and melt curve analysis. Conventional PCR served as a gold standard. Overall, for positive and negative concordance, cassette PCR was 98.6% concordant with conventional PCR, and BAX PCR was 65.4% concordant. Of 806 beef carcass swabs, 339 by cassette PCR and 84 by BAX PCR harbored eae + stx+E. coli. For BAX PCR reactions, 84% of eae+ swabs, 79% of stx+ swabs, and 86% of eae + stx+ swabs were also detected by cassette PCR. For cassette PCR reactions, 457 swabs were eae+ with only 117 scored as eae+ using BAX PCR for 26% positive concordance. For stx primers, cassette PCR scored 480 samples as stx+ but only 215 samples were stx+ by BAX PCR, giving 45% positive concordance. Importantly, cassette PCR scored 339 swabs as harboring eae + stx+ E. coli, but BAX PCR detected only 71 positives giving only 21% positive concordance, with many false negatives. Cassette PCR is a highly sensitive method for detection of STEC genes in E. coli found in carcass swabs.
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Affiliation(s)
- Dammika P. Manage
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Ag/For Centre, Edmonton, AB T6G 2P5, Canada; (D.P.M.); (J.L.)
| | - Jana Lauzon
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Ag/For Centre, Edmonton, AB T6G 2P5, Canada; (D.P.M.); (J.L.)
| | - Linda M. Pilarski
- Department of Oncology, University of Alberta and Cross Cancer Institute, 11560 University Ave, Edmonton, AB T6G 1Z2, Canada;
| | - Patrick M. Pilarski
- 5-005 Katz Group Centre for Pharmacy and Health Research, Department of Medicine, Division of Physical Medicine & Rehabilitation, University of Alberta, Edmonton, AB T6G 2E1, Canada;
| | - Lynn M. McMullen
- Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-10 Ag/For Centre, Edmonton, AB T6G 2P5, Canada; (D.P.M.); (J.L.)
- Correspondence:
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Roumani F, Azinheiro S, Carvalho J, Prado M, Garrido-Maestu A. Loop-mediated isothermal amplification combined with immunomagnetic separation and propidium monoazide for the specific detection of viable Listeria monocytogenes in milk products, with an internal amplification control. Food Control 2021. [DOI: 10.1016/j.foodcont.2021.107975] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Development of a genomic DNA reference material for Salmonella enteritidis detection using polymerase chain reaction. Mol Cell Probes 2020; 55:101690. [PMID: 33345976 DOI: 10.1016/j.mcp.2020.101690] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 11/28/2020] [Accepted: 12/11/2020] [Indexed: 01/18/2023]
Abstract
Several rapid methods based on nucleic acids can detect foodborne pathogens, such as Salmonella spp. However, a common reference that enables metrological traceability among measurement results is not available. Reference materials (RM) are thus key to guarantee methodological comparability. This study developed a candidate genomic DNA reference material for Salmonella enteritidis quantification to establish performance conditions and reference values for normalized RM production. The growth of Salmonella enteritidis ATCC® 13076 in Rappaport Vassiliadis selective medium was characterized, and we optimized a method of DNA extraction using cetrimonium bromide (CTAB) and LiCl. In a first stage six concentrations of DNA were prepared with and without yeast RNA (40 ng/μL) to evaluate its effect as a stabilizer in terms of homogeneity and short-term stability. Based on the findings, in a second stage two DNA concentrations were prepared and a reference value with its uncertainty was assigned based on the results of characterization, homogeneity, and stability studies using digital polymerase chain reaction and the gene targets, invA, ttr, and hilA. The material was stable for 9 months at 4 °C, with a expanded uncertainty contribution range of 11%-14%. The novel candidate RM is the first to be developed nationwide and will improve the quality of measurements in the area of food safety.
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Labchip-based diagnosis system for on-site application: Sensitive and easy-to-implement detection of single recoverable Cronobacter in infant formula without post-enrichment treatment. Int J Food Microbiol 2020; 327:108659. [PMID: 32413591 DOI: 10.1016/j.ijfoodmicro.2020.108659] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 11/20/2022]
Abstract
Microfluidic labchips have achieved much advancement in the molecular diagnosis of foodborne pathogens. Whereas difficulties in the flow control during the transportation of liquid fluids can occur and should be overcome. Manipulations of reaction temperature and the complex procedures from sample pre-treatment to analysis in a single chip device are major obstacles for the on-site application. Thus, the efficient temperature control of samples without any flow of reaction fluids in microfluidic channels of plastic chip and the simplest protocol omitting post-enrichment processing steps may overcome these limitations represented by the stability and the complexity, respectively. This study aims to develop a novel type of labchip and thermocycler specialized for the gene amplification in microfluidic channels and to evaluate the detectability by sensing the minimum recoverable level of Cronobacter in powdered infant formula (PIF). We developed a thermocycling device accelerating reactions through dual heating-blocks optimized to control temperatures of samples in microfluidic-channels by direct contact with labchip sequentially and repetitively. The structural design of microfluidic channels was to eliminate interference factors associated with the optical detection of fluorescent signals (without distortion due to air bubbles in the reaction chamber). To improve the applicability, a portable device and simplified operation to allow direct loading of samples in the chip without post-enrichment procedures were also adopted. Detection performance was evaluated by a sensitivity/specificity tests using 50 isolates of Cronobacter. Cross-reactivity tests for non-Cronobacter organisms and gDNA [human, raw materials of PIF (cow, soybean)] showed that there was no interference-factor causing false-positive results. In terms of the applied research conducted by using PIF, the enrichment of samples without broth medium (distilled water) displayed outstanding performance and 12 h of incubation facilitated detecting target at concentration as low as 1 CFU/300 g PIF (as initial contamination level) without post-enrichment treatment. Validation of the operation conditions using 30 commercial PIF products was also consistent. The present study presents a novel approach of microfluidic technology with perspective to not only the performance and the practicability [easy-to-implement protocol, portable materials, cost-effectiveness (the use of a miniaturized plastic chip requires a minimum level of materials)] for on-site diagnosis.
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Namroodi S. Detection of Zoonotic Antibiotic Resistant Salmonella spp. Carrying Virulence Genes in Rural Mus musculus, Golestan Province, North of Iran. INTERNATIONAL JOURNAL OF EPIDEMIOLOGIC RESEARCH 2019. [DOI: 10.15171/ijer.2019.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Background and aims: Salmonella spp. infect cold-blooded and warm-blooded animals and may cause a worldwide zoonotic disease, salmonellosis, in infected animals. Rodents can be Salmonella carriers without any signs of salmonellosis. The frequency of salmonella contamination, the presence of virulence genes (SpvR and SpvB) and antibiotic resistance pattern of isolated Salmonella were studied in rural Mus musculus to reveal the possible role of them in Salmonella dissemination in Golestan province. Methods: A total of 190 wet rectal swabs of M. musculus were obtained from rural areas of Golestan province with different climate conditions. The swabs were cultured and positive samples were serotyped and their antibiotic resistance patterns were studied. The presence of Salmonella and virulence genes was analyzed by SpvR and SpvB genes primers, respectively. Results: Salmonella spp. were detected in 15 (7%) of 190 fecal samples by bacterial culture and PCR. S. enteritidis (n=9) and S. typhimurium (n=6) were identified. The highest and lowest frequencies were detected in humid (13.1%) and arid areas (3.1%), respectively. SpvR and SpvB genes were diagnosed in 10 of 15 (66.6%) isolated Salmonella. The highest resistance of detected Salmonella spp. was observed against streptomycin (53%). All the isolates were sensitive to chloramphenicol, gentamicin and trimethoprim. Conclusion: The Salmonella contamination in sampled house mice indicates that native people should be made aware of the risk of Salmonella infection and possible ways of salmonella transmission through rodents. In addition, the application of appropriate therapeutic approaches to prevent the spread of antibiotic resistant Salmonella is recommended.
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Affiliation(s)
- Somayeh Namroodi
- Department of Environmental sciences, Faculty of fisheries and environmental Sciences, Gorgan University of Agricultural Sciences & Natural Resources, Gorgan, Iran
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Wei C, Zhong J, Hu T, Zhao X. Simultaneous detection of Escherichia coli O157:H7, Staphylococcus aureus and Salmonella by multiplex PCR in milk. 3 Biotech 2018; 8:76. [PMID: 29354387 PMCID: PMC5767162 DOI: 10.1007/s13205-018-1086-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 01/02/2018] [Indexed: 01/08/2023] Open
Abstract
Escherichia coli O157:H7, Staphylococcus aureus, and Salmonella are food-borne pathogens that cause serious gastrointestinal illness and frequent food safety accidents. This study aimed to develop a practical multiplex polymerase chain reaction (mPCR) technique for the simultaneous detection of these food-borne pathogens in culture broth and artificial food matrix. Pathogen-specific DNA sequences in the rfbE, nuc, and invA genes were used as targets to design primers for the identification of E. coli O157:H7, S. aureus, and Salmonella, respectively. As expected, the method produced species-specific bands of amplified products without any contaminating non-specific bands. The highest species specificity was established with primer concentrations of 0.1, 0.2, and 0.4 μM for E. coli O157:H7, S. aureus, and Salmonella, correspondingly. The detection sensitivity of this assay was 103 CFU/mL in culture broth, and the limit of detection was consistent with singleplex PCR in the food sample. The mPCR assay proposed here is an easy and convenient detection method, which will be valuable for microbial epidemiology and food safety investigations.
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Affiliation(s)
- Caijiao Wei
- Key Laboratory for Green Chemical Process of Ministry of Education, Key Laboratory for Hubei Novel Reactor & Green Chemical Technology, Research Center for Environmental Ecology and Engineering, School of Environmental Ecology and Biological Engineering, Wuhan Institute of Technology, Wuhan, 430205 China
| | - Junliang Zhong
- Key Laboratory for Green Chemical Process of Ministry of Education, Key Laboratory for Hubei Novel Reactor & Green Chemical Technology, Research Center for Environmental Ecology and Engineering, School of Environmental Ecology and Biological Engineering, Wuhan Institute of Technology, Wuhan, 430205 China
| | - Ting Hu
- Key Laboratory for Green Chemical Process of Ministry of Education, Key Laboratory for Hubei Novel Reactor & Green Chemical Technology, Research Center for Environmental Ecology and Engineering, School of Environmental Ecology and Biological Engineering, Wuhan Institute of Technology, Wuhan, 430205 China
| | - Xihong Zhao
- Key Laboratory for Green Chemical Process of Ministry of Education, Key Laboratory for Hubei Novel Reactor & Green Chemical Technology, Research Center for Environmental Ecology and Engineering, School of Environmental Ecology and Biological Engineering, Wuhan Institute of Technology, Wuhan, 430205 China
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Li X, Liu L, Li Q, Xu G, Zheng J. Salmonella Enteritidis in Layer Farms of Different Sizes Located in Northern China: On-Farm Sampling and Detection by the PCR Method. BRAZILIAN JOURNAL OF POULTRY SCIENCE 2017. [DOI: 10.1590/1806-9061-2016-0318] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- X Li
- China Agricultural University, China
| | - L Liu
- China Agricultural University, China
| | - Q Li
- China Agricultural University, China
| | - G Xu
- China Agricultural University, China
| | - J Zheng
- China Agricultural University, China
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Koo EJ, Kim D, Oh SW. Comparison of DNA isolation methods for detection of foodborne pathogens by real-time PCR from foods. ACTA ACUST UNITED AC 2016. [DOI: 10.9721/kjfst.2016.48.4.335] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Improvement of Enterobacteriaceae enrichment broth by supplementation with sodium citrate for detection of Cronobacter sakazakii using real-time PCR. Food Sci Biotechnol 2016; 25:1205-1209. [PMID: 30263395 DOI: 10.1007/s10068-016-0191-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 06/07/2016] [Accepted: 06/07/2016] [Indexed: 10/21/2022] Open
Abstract
Enterobacteriaceae enrichment (EE) broth, a selective enrichment medium for Cronobacter sakazakii detection, has been shown to contain polymerase chain reaction (PCR) inhibitors. Therefore, a modified enrichment broth was developed, wherein possible PCR inhibitors, brilliant green and bile salts, were substituted with sodium citrate. Investigations were conducted to determine whether realtime PCR detection of C. sakazakii in powdered infant formula and dried vegetables with this modified medium improved compared with conventional culture methods. The detection rate of the modified EE broth was significantly higher (p<0.05) than that of the conventional EE broth for both types of food. For dried pumpkin samples, real-time PCR after culturing in modified EE broth yielded significantly higher detection rates and selectivity than those achieved using conventional culture in Druggan-Forsythe-Iversen agar. These results show that real-time PCR after enrichment in the modified EE broth may be an effective screening method for detection of C. sakazakii.
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Wang H, Turechek WW. A Loop-Mediated Isothermal Amplification Assay and Sample Preparation Procedure for Sensitive Detection of Xanthomonas fragariae in Strawberry. PLoS One 2016; 11:e0147122. [PMID: 26766068 PMCID: PMC4713083 DOI: 10.1371/journal.pone.0147122] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 12/29/2015] [Indexed: 11/18/2022] Open
Abstract
Xanthomonas fragariae is a bacterium that causes angular leaf spot of strawberry. Asymptomatic infection is common and contributes to the difficulties in disease management. The aim of this study was to develop a loop-mediated isothermal amplification (LAMP) assay as an efficient method for detection of asymptomatic infections of X. fragariae. In addition, a new method of sample preparation was developed that allows sampling of a larger amount of plant tissue, hence increasing the detection rate in real-life samples. The sample preparation procedure includes an overnight incubation of strawberry tissues in phosphate-buffered saline (PBS), followed by a quick sample concentration and a boiling step to extract DNA for amplification. The detection limit of the LAMP assay was approximately 2×10(3) CFU/mL for pure bacteria culture and 300 CFU/mL for bacteria spiked strawberry leaf and petiole samples. LAMP provided a 2-3 fold lower detection limit than the standard qPCR assay but was faster, and more user-friendly. The LAMP assay should serve as a rapid, sensitive and cost-effective tool for detecting asymptomatic infections of X. fragariae in strawberry nursery stock and contribute to improved disease management.
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Affiliation(s)
- Hehe Wang
- U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), U.S. Horticultural Research Laboratory, Fort Pierce, FL, United States of America
| | - William W. Turechek
- U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), U.S. Horticultural Research Laboratory, Fort Pierce, FL, United States of America
- * E-mail:
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14
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Salmonella spp. contamination in fresh pork and chicken sausages marketed in Niterói and Rio de Janeiro, Brazil. J Verbrauch Lebensm 2014. [DOI: 10.1007/s00003-014-0901-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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15
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Amalia U, Dewanti-Hariyadi R, Poernomo A. RAPID DETECTION OF Salmonella IN SHRIMP BY POLYMERASE CHAIN REACTION. JURNAL TEKNOLOGI DAN INDUSTRI PANGAN 2014. [DOI: 10.6066/jtip.2014.25.1.78] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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16
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de Almeida MV, Silva A, Nero LA. Evaluation of target sequences for the polymerase chain reaction-based detection of Salmonella in artificially contaminated beef. Foodborne Pathog Dis 2013; 11:111-8. [PMID: 24102080 DOI: 10.1089/fpd.2013.1623] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Salmonella is a major cause of foodborne diseases worldwide, which has fueled the demand for the development and evaluation of sensitive, specific, and rapid detection methodologies, such as polymerase chain reaction (PCR). In this study, six primer pairs for the detection of Salmonella were evaluated by PCR with isolates of Salmonella spp. (115) and other bacteria (104). The primers designed for the sifB gene provided the best performance regarding specificity and sensitivity (100%). These primers were selected and used to develop a PCR assay for Salmonella detection during the enrichment steps of the conventional detection method in spiked beef samples. The enrichment steps were: buffered peptone water (BPW), Rappaport-Vassiliadis soya broth (RVS) and at the Müller-Kauffmann tetrathionate novobiocin broth (MKTTn), after 18 h (BPW) and 24 h (RVS and MKTTn) of incubation. The initial concentrations of the Salmonella inocula were 10¹, 10², and 10³ colony-forming units/25 g. The protocol was able to detect Salmonella at all concentrations in the enrichment steps, but not in the nonenriched samples. These results indicated that the proposed protocol was suitable to detect Salmonella in beef during the intermediate stages of the conventional isolation protocol, substantially reducing the time required to obtain the final results.
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17
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Manguiat LS, Fang TJ. Evaluation of DAS™ kits for the detection of food-borne pathogens in chicken- and meat-based street-vended foods. J Food Drug Anal 2013. [DOI: 10.1016/j.jfda.2013.05.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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18
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Garrido A, Chapela MJ, Román B, Fajardo P, Vieites JM, Cabado AG. In-house validation of a multiplex real-time PCR method for simultaneous detection of Salmonella spp., Escherichia coli O157 and Listeria monocytogenes. Int J Food Microbiol 2013; 164:92-8. [PMID: 23624537 DOI: 10.1016/j.ijfoodmicro.2013.03.024] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 02/24/2013] [Accepted: 03/26/2013] [Indexed: 10/27/2022]
Abstract
A wide variety of qPCR methods currently exist for Salmonella spp., Escherichia coli O157 and Listeria monocytogenes detection. These methods target several genes and use different detection chemistries, either in simplex or in multiplex formats. However, the majority of these methods have not been carefully validated, and the number of validated methods that use multiplex qPCR is even lower. The aim of the present study was to develop and validate a multiplex qPCR method from previously validated simplex qPCR primers and probes. A modified broth medium was selected and primary and secondary enrichment times were further optimized. Efficiency of the newly combined qPCR system was comprised between 91% and 108%, for simplex and multiplex analyses. A total of 152 food and environmental, natural and spiked samples, were analyzed for the evaluation of the method obtaining values above 91% that were reached for all the quality parameters analyzed. A very low limit of detection (5 cfu/25 g after enrichment) for simultaneous identification of these 3 pathogens was obtained.
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Affiliation(s)
- Alejandro Garrido
- Microbiology and Toxins Area, ANFACO-CECOPESCA, Campus Univ. 16, 36310 Vigo PO, Spain
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A new multiplex real-time PCR developed method for Salmonella spp. and Listeria monocytogenes detection in food and environmental samples. Food Control 2013. [DOI: 10.1016/j.foodcont.2012.06.029] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Martin B, Garriga M, Aymerich T. Pre-PCR treatments as a key factor on the probability of detection of Listeria monocytogenes and Salmonella in ready-to-eat meat products by real-time PCR. Food Control 2012. [DOI: 10.1016/j.foodcont.2012.03.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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21
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Occurrence of Salmonella spp. in samples from pigs slaughtered for consumption: A comparison between ISO 6579:2002 and 23S rRNA Fluorescent In Situ Hybridization method. Food Res Int 2012. [DOI: 10.1016/j.foodres.2010.08.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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