scholarly journals Quantification of Campylobacter spp. in Chicken Rinse Samples by Using Flotation prior to Real-Time PCR

2005 ◽  
Vol 71 (10) ◽  
pp. 5759-5764 ◽  
Author(s):  
Petra Wolffs ◽  
Börje Norling ◽  
Jeffrey Hoorfar ◽  
Mansel Griffiths ◽  
Peter Rådström
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Quantitative Data ◽  
Buoyant Density ◽  
Tetrazolium Chloride ◽  
Viable Cells ◽  
Flotation Treatment ◽  
Flotation Method ◽  
Cell Concentrations ◽  
Campylobacter Spp

ABSTRACT Real-time PCR is fast, sensitive, specific, and can deliver quantitative data; however, two disadvantages are that this technology is sensitive to inhibition by food and that it does not distinguish between DNA originating from viable, viable nonculturable (VNC), and dead cells. For this reason, real-time PCR has been combined with a novel discontinuous buoyant density gradient method, called flotation, in order to allow detection of only viable and VNC cells of thermotolerant campylobacters in chicken rinse samples. Studying the buoyant densities of different Campylobacter spp. showed that densities changed at different time points during growth; however, all varied between 1.065 and 1.109 g/ml. These data were then used to develop a flotation assay. Results showed that after flotation and real-time PCR, cell concentrations as low as 8.6 × 102 CFU/ml could be detected without culture enrichment and amounts as low as 2.6 × 103 CFU/ml could be quantified. Furthermore, subjecting viable cells and dead cells to flotation showed that viable cells were recovered after flotation treatment but that dead cells and/or their DNA was not detected. Also, when samples containing VNC cells mixed with dead cells were treated with flotation after storage at 4 or 20°C for 21 days, a similar percentage resembling the VNC cell fraction was detected using real-time PCR and 5-cyano-2,3-ditolyl tetrazolium chloride-4′,6′-diamidino-2-phenylindole staining (20% ± 9% and 23% ± 4%, respectively, at 4°C; 11% ± 4% and 10% ± 2%, respectively, at 20°C). This indicated that viable and VNC Campylobacter cells could be positively selected and quantified using the flotation method.

scholarly journals Molecular Analyses of Fecal Bacteria and Hydrodynamic Modeling for Microbial Risk Assessment of a Drinking Water Source

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 3
Author(s):  
Olga D. Chuquimia ◽  
Viktor Bergion ◽  
Jessica Guzman-Otazo ◽  
Kaisa Sörén ◽  
Lars Rosén ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Real Time ◽  
Water Intake ◽  
Real Time Pcr ◽  
Hydrodynamic Modeling ◽  
Salmonella Spp ◽  
Molecular Analyses ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Campylobacter Spp

Safe water is a global concern, and methods to accurately monitor quality of water are vital. To assess the risks related to bacterial pathogen load in Lake Vomb that provides drinking water to the southern part of Sweden, this study combined molecular analyses of enterobacteria and bacterial pathogens in water using quantitiative real-time PCR with hydrodynamic modeling and quantitative microbial risk assessment (QMRA). A real-time PCR assay to detect enterobacteria was set up by primers targeting ssrA. Between February 2015 and May 2016, presence of ssrA gene copies as well as Campylobacter spp., Salmonella spp., and EHEC O157 DNA was analyzed by real-time PCR at several locations in the catchment of Lake Vomb and its tributaries Björkaån, Borstbäcken, and Torpsbäcken. Björkaån had the highest detected concentrations of the ssrA gene and, according to the results of hydrodynamic modeling, contributed most to the contamination of the water intake in the lake. None of the water samples were positive for genes encoding EHEC O157 and Campylobacter spp., while invA (Salmonella spp.) was present in 11 samples. The QMRA showed that the suggested acceptable risk level (daily probability of infection <2.7 × 10−7) is achieved with a 95% probability, if the Salmonella concentrations in the water intake are below 101 bacteria/100 mL. If a UV-disinfection step is installed, the Salmonella concentration at the water intake should not exceed 106 bacteria/100 mL.

Isolation and Identification of Campylobacter spp. from Poultry and Poultry By-Products in Tunisia by Conventional Culture Method and Multiplex Real-Time PCR

2017 ◽  
Vol 80 (10) ◽  
pp. 1623-1627 ◽  
Author(s):  
Hela Jribi ◽  
Hanen Sellami ◽  
Siala Mariam ◽  
Salma Smaoui ◽  
Asma Ghorbel ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Poultry Meat ◽  
Culture Methods ◽  
Isolation And Identification ◽  
Conventional Culture ◽  
Multiplex Pcr Assay ◽  
Thermophilic Campylobacter ◽  
By Products ◽  
Campylobacter Spp

ABSTRACT Thermophilic Campylobacter spp. are one of the primary causes of bacterial human diarrhea. The consumption of poultry meats, by-products, or both is suspected to be a major cause of human campylobacteriosis. The aims of this study were to determine the prevalence of thermophilic Campylobacter spp. in fresh poultry meat and poultry by-products by conventional culture methods and to confirm Campylobacter jejuni and Campylobacter coli isolates by using the multiplex PCR assay. Two hundred fifty fresh poultry samples were collected from a variety of supermarkets and slaughterhouses located in Sfax, Tunisia, including chicken (n =149) and turkey (n =101). The samples were analyzed using conventional microbiological examinations according to the 2006 International Organization for Standardization method (ISO 10272-1) for Campylobacter spp. Concurrently, a real-time PCR was used for identification of C. jejuni and C. coli. Of the 250 samples of poultry meat and poultry by-products, 25.6% (n = 64) were contaminated with Campylobacter spp. The highest prevalence of Campylobacter spp. was found in chicken meat (26.8%) followed by turkey meat (23.7%). Among the different products, poultry breasts showed the highest contamination (36.6%) followed by poultry by-products (30%), poultry wings (28%) and poultry legs (26%) showed the lowest contamination, and no contamination was found on neck skin. Of the 64 thermophilic Campylobacter isolates, C. jejuni (59.7%) was the most frequently isolated species and 10.9% of the isolates were identified as C. coli. All of the 64 Campylobacter isolates identified by the conventional culture methods were further confirmed by PCR. The seasonal peak of Campylobacter spp. contamination was in the warm seasons (spring and summer). The study concluded that high proportions of poultry meat and poultry by-products marketed in Tunisia are contaminated by Campylobacter spp. Furthermore, to ensure food safety, poultry meats must be properly cooked before consuming.

scholarly journals Detection and quantification of Campylobacter in foods: New analytic approaches to detect and quantify Campylobacter spp. in food samples

2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Maria Francesca Peruzy ◽  
Yolande Thérèse Rose Proroga ◽  
Federico Capuano ◽  
Federica Corrado ◽  
Serena Santonicola ◽  
...  
Keyword(s):  
Real Time ◽  
Campylobacter Jejuni ◽  
Internal Control ◽  
Real Time Pcr ◽  
Quantitative Methods ◽  
Bacterial Load ◽  
Digital Pcr ◽  
Food Samples ◽  
Meat Samples ◽  
Campylobacter Spp

The aim of the present study was to develop rapid qualitative and quantitative methods based on the use of Real-Time PCR and Droplet Digital PCR (ddPCR), in order to have reliable techniques to detect and quantify Campylobacter spp. in food samples. The gene 16S-rRNA was used as specific target for Campylobacter spp. Real- Time PCR evaluation assay and a not competitive internal control was ushered in it. To investigate the selectivity of the method, 26 Campylobacter strains and 40 non-Campylobacter strains were tested and in order to verify the application of Real-Time PCR method, 5 pork meat samples were experimentally inoculated with a Campylobacter jejuni strain. Subsequently, dilutions with a bacterial load of Campylobacter jejuni within 10-106 CFU/mL were chosen for the optimization of the ddPCR assay. Lastly, a total of 54 naturally contaminated foods samples were analyzed through molecular (Real-Time PCR and ddPCR) and traditional methods. The Real-Time PCR protocol demonstrated to amplify only the Campylobacter spp. strains and when Campylobacter jejuni was experimentally inoculated in meat samples the pathogen was always detected. The ddPCRs assay allowed to quantify a level of contamination of 10 CFU/mL, but it was unable to quantify levels of 105 – 106 CFU/mL. Lastly, Campylobacter spp. was never detected in the 54 samples tested. In conclusion, the novel analytic approach proposed, based on an initial screening of the samples with Real-Time PCR and then on quantification of Campylobacter spp. with a ddPCR on those positive, represents a quick monitoring tool and, if used correctly, it would allow the implementation of food safety.

scholarly journals Quantification of Viable Cells of Pseudomonas syringae pv. tomato in Tomato Seed Using Propidium Monoazide and a Real-Time PCR Assay

Plant Disease ◽  
2020 ◽  
Vol 104 (8) ◽  
pp. 2225-2232
Author(s):  
A-li Chai ◽  
Hai-yan Ben ◽  
Wei-tao Guo ◽  
Yan-xia Shi ◽  
Xue-wen Xie ◽  
...  
Keyword(s):  
Real Time ◽  
Pseudomonas Syringae ◽  
Real Time Pcr ◽  
Light Exposure ◽  
Qpcr Assay ◽  
Bacterial Suspension ◽  
Propidium Monoazide ◽  
Chromosomal Dna ◽  
Tomato Seed ◽  
Viable Cells

Pseudomonas syringae pv. tomato is a seedborne pathogen that causes bacterial speck disease in tomato. P. syringae pv. tomato is typically detected in tomato seed using quantitative real-time PCR (qPCR) but the inability of qPCR to distinguish between viable and nonviable cells might lead to an overestimation of viable P. syringae pv. tomato cells. In the present study, a strategy involving a propidium monoazide (PMA) pretreatment followed by a qPCR (PMA-qPCR) assay was developed for quantifying viable P. syringae pv. tomato cells in contaminated tomato seed. PMA could selectively bind to the chromosomal DNA of dead bacterial cells and, therefore, block DNA amplification of qPCR. The primer pair Pst3F/Pst3R was designed based on gene hrpZ to specifically amplify and quantify P. syringae pv. tomato by qPCR. The PMA pretreatment protocol was optimized for selectively detecting viable P. syringae pv. tomato cells, and the optimal PMA concentration and light exposure time were 10 μmol liter−1 and 10 min, respectively. In the sensitivity test, the detection limit of PMA-qPCR for detecting viable cells in bacterial suspension and artificially contaminated tomato seed was 102 CFU ml−1 and 11.86 CFU g−1, respectively. For naturally contaminated tomato seed, viable P. syringae pv. tomato cells were quantified in 6 of the 19 samples, with infestation levels of approximately 102 to 104 CFU g−1. The results indicated that the PMA-qPCR assay is a suitable tool for quantifying viable P. syringae pv. tomato cells in tomato seed, which could be useful for avoiding the potential risks of primary inoculum sources from contaminated seed.

scholarly journals Rapid Identification of Campylobacter spp. by Melting Peak Analysis of Biprobes in Real-Time PCR

2001 ◽  
Vol 39 (6) ◽  
pp. 2227-2232 ◽  
Author(s):  
J. M. J. Logan ◽  
K. J. Edwards ◽  
N. A. Saunders ◽  
J. Stanley
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Rapid Identification ◽  
Melting Peak ◽  
Campylobacter Spp
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