Evaluation of a Multiplex PCR Assay for the Identification of Salmonella Serovars Enteritidis and Typhimurium Using Retail and Abattoir Samples

2017 ◽  
Vol 80 (2) ◽  
pp. 295-301 ◽  
Author(s):  
Dele Ogunremi ◽  
Susan Nadin-Davis ◽  
Andrée Ann Dupras ◽  
Imelda Gálvan Márquez ◽  
Katayoun Omidi ◽  
...  

ABSTRACT A multiplex PCR was developed to identify the two most common serovars of Salmonella causing foodborne illness in Canada, namely, serovars Enteritidis and Typhimurium. The PCR was designed to amplify DNA fragments from four Salmonella genes, namely, invA gene (211-bp fragment), iroB gene (309-bp fragment), Typhimurium STM 4497 (523-bp fragment), and Enteritidis SE147228 (612-bp fragment). In addition, a 1,026-bp ribosomal DNA (rDNA) fragment universally present in bacterial species was included in the assay as an internal control fragment. The detection rate of the PCR was 100% among Salmonella Enteritidis (n = 92) and Salmonella Typhimurium (n = 33) isolates. All tested Salmonella isolates (n = 194) were successfully identified based on the amplification of at least one Salmonella-specific DNA fragment. None of the four Salmonella DNA amplicons were detected in any of the non-Salmonella isolates (n = 126), indicating an exclusivity rate of 100%. When applied to crude extracts of 2,001 field isolates of Salmonella obtained during the course of a national microbiological baseline study in broiler chickens and chicken products sampled from abattoir and retail outlets, 163 isolates, or 8.1%, tested positive for Salmonella Enteritidis and another 80 isolates, or 4.0%, tested as Salmonella Typhimurium. All isolates identified by serological testing as Salmonella Enteritidis in the microbiological study were also identified by using the multiplex PCR. The new test can be used to identify or confirm pure isolates of the two serovars and is also amenable for integration into existing culture procedures for accurate detection of Salmonella colonies.

2020 ◽  
Vol 12 (2) ◽  
pp. 212-217 ◽  
Author(s):  
Juan Du ◽  
Shujing Wu ◽  
Liyuan Niu ◽  
Junguang Li ◽  
Dianbo Zhao ◽  
...  

Unfunctionalized flower-shaped AuNPs is used as colorimetric sensor for PCR product detection by naked eyes.


2001 ◽  
Vol 67 (12) ◽  
pp. 5694-5699 ◽  
Author(s):  
Miia Lindström ◽  
Riikka Keto ◽  
Annukka Markkula ◽  
Mari Nevas ◽  
Sebastian Hielm ◽  
...  

ABSTRACT Botulism is diagnosed by detecting botulinum neurotoxin andClostridium botulinum cells in the patient and in suspected food samples. In this study, a multiplex PCR assay for the detection of Clostridium botulinum types A, B, E, and F in food and fecal material was developed. The method employs four new primer pairs with equal melting temperatures, each being specific to botulinum neurotoxin gene type A, B, E, or F, and enables a simultaneous detection of the four serotypes. A total of 43 C. botulinum strains and 18 strains of other bacterial species were tested. DNA amplification fragments of 782 bp for C. botulinum type A alone, 205 bp for type B alone, 389 bp for type E alone, and 543 bp for type F alone were obtained. Other bacterial species, including C. sporogenes and the nontoxigenic nonproteolytic C. botulinum-like organisms, did not yield a PCR product. Sensitivity of the PCR for types A, E, and F was 102 cells and for type B was 10 cells per reaction mixture. With a two-step enrichment, the detection limit in food and fecal samples varied from 10−2 spore/g for types A, B, and F to 10−1 spore/g of sample material for type E. Of 72 natural food samples investigated, two were shown to contain C. botulinum type A, two contained type B, and one contained type E. The assay is sensitive and specific and provides a marked improvement in the PCR diagnostics of C. botulinum.


2011 ◽  
Vol 02 (06) ◽  
pp. 456-462
Author(s):  
Fabiana de Almeida Rufino ◽  
Marcelo Marcondes Seneda ◽  
Alice Fernandes Alfieri ◽  
Katia Cristina Silva-Santos ◽  
Karina Cristina Puggesi Rubin ◽  
...  

2017 ◽  
Vol 55 (9) ◽  
pp. 2617-2628 ◽  
Author(s):  
Kate J. Howell ◽  
Lucy A. Weinert ◽  
Sarah E. Peters ◽  
Jinhong Wang ◽  
Juan Hernandez-Garcia ◽  
...  

ABSTRACTHaemophilus parasuisis a diverse bacterial species that is found in the upper respiratory tracts of pigs and can also cause Glässer's disease and pneumonia. A previous pangenome study ofH. parasuisidentified 48 genes that were associated with clinical disease. Here, we describe the development of a generalized linear model (termed a pathotyping model) to predict the potential virulence of isolates ofH. parasuisbased on a subset of 10 genes from the pangenome. A multiplex PCR (mPCR) was constructed based on these genes, the results of which were entered into the pathotyping model to yield a prediction of virulence. This new diagnostic mPCR was tested on 143 field isolates ofH. parasuisthat had previously been whole-genome sequenced and a further 84 isolates from the United Kingdom from cases ofH. parasuis-related disease in pigs collected between 2013 and 2014. The combination of the mPCR and the pathotyping model predicted the virulence of an isolate with 78% accuracy for the original isolate collection and 90% for the additional isolate collection, providing an overall accuracy of 83% (81% sensitivity and 93% specificity) compared with that of the “current standard” of detailed clinical metadata. This new pathotyping assay has the potential to aid surveillance and disease control in addition to serotyping data.


2020 ◽  
Vol 110 (3) ◽  
pp. 556-566
Author(s):  
Shree P. Thapa ◽  
Michael O’Leary ◽  
Marie-Agnès Jacques ◽  
Robert L. Gilbertson ◽  
Gitta Coaker

Clavibacter michiganensis is a Gram-positive bacterial pathogen that proliferates in the xylem vessels of tomato, causing bacterial wilt and canker symptoms. Accurate detection is a crucial step in confirming outbreaks of bacterial canker and developing management strategies. A major problem with existing detection methods are false-positive and -negative results. Here, we report the use of comparative genomics of 37 diverse Clavibacter strains, including 21 strains sequenced in this study, to identify specific sequences that are C. michiganensis detection targets. Genome-wide phylogenic analyses revealed additional diversity within the genus Clavibacter. Pathogenic C. michiganensis strains varied in plasmid composition, highlighting the need for detection methods based on chromosomal targets. We utilized sequences of C. michiganensis-specific loci to develop a multiplex PCR-based diagnostic platform using two C. michiganensis chromosomal genes (rhuM and tomA) and an internal control amplifying both bacterial and plant DNA (16s ribosomal RNA). The multiplex PCR assay specifically detected C. michiganensis strains from a panel of 110 additional bacteria, including other Clavibacter spp. and bacterial pathogens of tomato. The assay was adapted to detect the presence of C. michiganensis in seed and tomato plant materials with high sensitivity and specificity. In conclusion, the described method represents a robust, specific tool for detection of C. michiganensis in tomato seed and infected plants.


Plant Disease ◽  
2015 ◽  
Vol 99 (3) ◽  
pp. 333-341 ◽  
Author(s):  
Michael J. Stulberg ◽  
Jonathan Shao ◽  
Qi Huang

Ralstonia solanacearum race 3 biovar 2 strains are considered select agents by the U.S. government because they are not endemic to the United States and have the potential to cause brown rot in our potato production fields. Simple and accurate methods are needed for quick identification prior to more discriminating but time-consuming verification methods. We developed a multiplex PCR assay that identifies R. solanacearum species complex strains, signals whether the strain detected is a select agent, and controls for false negatives associated with PCR inhibition or unsuccessful DNA extractions in one reaction. We identified unique sequences of non-phage-related DNA for the R. solanacearum species complex strains, and for select agent strains, using in silico genome subtraction. We also designed and included an internal plant DNA control assay. Our multiplex PCR assay correctly identified 90 R. solanacearum species complex strains and 34 select agent strains, while not recognizing five out-group bacterial species. Additionally, the multiplex PCR assay facilitated the detection of plant DNA and R. solanacearum from infected tomato, potato, geranium, and tobacco plants. Our rapid, accurate, and reliable detection assay can help government officials make timely and appropriate recommendations to exclude this bacterium from the United States.


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