Accuracy and Sensitivity of Commercial PCR-Based Methods for Detection of
            <i>Salmonella enterica</i>
            in Feed

Koyuncu, Sevinc; Andersson, Matilda; Häggblom, Per

doi:10.1128/aem.02714-09

Cited by 43 publications

(33 citation statements)

References 37 publications

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“…The whole process usually takes 5 to 7 days to be completed. In the last few years, molecular diagnostic methods such as polymerase chain reaction (PCR) have been developed for the detection of Salmonella in much shorter time 5 . PCR allows for an accurate and unambiguous identification of target nucleic acid sequences.…”

Section: Introductionmentioning

confidence: 99%

A lab-on-a-chip system with integrated sample preparation and loop-mediated isothermal amplification for rapid and quantitative detection of Salmonella spp. in food samples

et al. 2015

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Foodborne disease is a major public health threat worldwide. Salmonellosis, an infectious disease caused by Salmonella spp., is one of the most common foodborne diseases. Isolation and identification of Salmonella by conventional bacterial culture or molecular-based methods are time consuming and usually take a few hours to days to complete. In response to the demand for rapid on line or at site detection of pathogens, in this study, we describe for the first time an eight-chamber lab-on-a-chip (LOC) system with integrated magnetic beads-based sample preparation and loop-mediated isothermal amplification (LAMP) for rapid and quantitative detection of Salmonella spp. in food samples. The whole diagnostic procedures including DNA isolation, isothermal amplification, and real-time detection were accomplished in a single chamber. Up to eight samples could be handled simultaneously and the system was capable to detect Salmonella at concentration of 50 cells per test within 40 min. The simple design, together with high level of integration, isothermal amplification, and quantitative analysis of multiple samples in short time will greatly enhance the practical applicability of the LOC system for rapid on-site screening of Salmonella for applications in food safety control, environmental surveillance, and clinical diagnostics.

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Section: Introductionmentioning

confidence: 99%

A lab-on-a-chip system with integrated sample preparation and loop-mediated isothermal amplification for rapid and quantitative detection of Salmonella spp. in food samples

et al. 2015

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“…These methods include DNA-based systems for the detection of pathogens in a variety of food samples. Although molecular protocols are faster than traditional plating methods, enrichment of the sample is still required to obtain the sensitivity level of 10 2 colony forming units (CFU) of the bacterial pathogen needed in polymerase chain reaction (PCR)-based methods 19 . Additionally, isolation of pure bacterial colonies from PCR-positive samples is needed to confirm the pathogen using appropriate methods.…”

Section: Introductionmentioning

confidence: 99%

Detection of Foodborne Bacterial Pathogens from Individual Filth Flies

Pava‐Ripoll

Pearson

Miller

et al. 2015

JoVE

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There is unanimous consensus that insects are important vectors of foodborne pathogens. However, linking insects as vectors of the pathogen causing a particular foodborne illness outbreak has been challenging. This is because insects are not being aseptically collected as part of an environmental sampling program during foodborne outbreak investigations and because there is not a standardized method to detect foodborne bacteria from individual insects. To take a step towards solving this problem, we adapted a protocol from a commercially available PCR-based system that detects foodborne pathogens from food and environmental samples, to detect foodborne pathogens from individual flies.Using this standardized protocol, we surveyed 100 wild-caught flies for the presence of Cronobacter spp., Salmonella enterica, and Listeria monocytogenes and demonstrated that it was possible to detect and further isolate these pathogens from the body surface and the alimentary canal of a single fly. Twenty-two percent of the alimentary canals and 8% of the body surfaces from collected wild flies were positive for at least one of the three foodborne pathogens. The prevalence of Cronobacter spp. on either body part of the flies was statistically higher (19%) than the prevalence of S. enterica (7%) and L.monocytogenes (4%). No false positives were observed when detecting S. enterica and L. monocytogenes using this PCR-based system because pure bacterial cultures were obtained from all PCR-positive results. However, pure Cronobacter colonies were not obtained from about 50% of PCR-positive samples, suggesting that the PCR-based detection system for this pathogen cross-reacts with other Enterobacteriaceae present among the highly complex microbiota carried by wild flies. The standardized protocol presented here will allow laboratories to detect bacterial foodborne pathogens from aseptically collected insects, thereby giving public health officials another line of evidence to find out how the food was contaminated when performing foodborne outbreak investigations.

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“…Human infection usually results from eating contaminated food, such as poultry, milk, beef, eggs, pork, and seafood (13); consequently, monitoring and control of contamination by Salmonella are necessary and important in the food industry.…”

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confidence: 99%

Lag Phase of Salmonella enterica under Osmotic Stress Conditions

Zhou

George

Métris

et al. 2011

Appl Environ Microbiol

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Salmonella enterica serovar Typhimurium was grown at salt concentrations ranging from 0.5 to 7.5% in minimal medium with and without added osmoprotectant and in a rich medium. In minimal medium, the cells showed an initial decline period, and consequently the definition of the lag time of the resultant log count curve was revised. The model of Baranyi and Roberts (Int. J. Food Microbiol. 23:277-294, 1994) was modified to take into account the initial decline period, based on the assumption that the log count curve of the total population was the sum of a dying and a surviving-then-growing subpopulation. The lag time was defined as the lag of the surviving subpopulation. It was modeled by means of a parameter quantifying the biochemical work the surviving cells carry out during this phase, the "work to be done." The logarithms of the maximum specific growth rates as a function of the water activity in the three media differed only by additive constants, which gave a theoretical basis for bias factors characterizing the relationships between different media. Models for the lag and the "work to be done" as a function of the water activity showed similar properties, but in rich medium above 5% salt concentrations, the data showed a maximum for this work. An accurate description of the lag time is important to avoid food wastage, which is an issue of increasing significance in the food industry, while maintaining food safety standards.Salmonella enterica causes severe enteritis in both humans and animals (19,25). Human infection usually results from eating contaminated food, such as poultry, milk, beef, eggs, pork, and seafood (13); consequently, monitoring and control of contamination by Salmonella are necessary and important in the food industry.One way of controlling Salmonella in food is to add salt to decrease the water activity and inhibit microbial growth. However, the effect of salt highly depends on the presence of osmoprotectants, which have been shown to affect the growth rate (7). The immediate response of cells to osmotic stress is to accumulate K ϩ and glutamine to maintain a viable turgor of the cell. These potentially harmful substrates are then replaced by compatible solutes, such as proline, trehalose, and glycine betaine, to stimulate growth (11). The compatible solutes either can be taken up from the growth medium if available or, if none are present, need to be synthesized de novo by the cell. Betaine (also known as glycine betaine or trimethylglycine) is one of the most common and effective osmolytes utilized by Salmonella spp. Although betaine cannot be synthesized by Salmonella enterica serovar Typhimurium, it can be transported from the growth medium under high external osmolality conditions (8). In the absence of osmoprotectants in the environment, trehalose is thought to be the main osmoprotectant synthesized by Escherichia coli and Salmonella.Predictive microbiology has become a main tool to describe the growth of microorganisms in recent years. Predictive models concentrate mainly on the ...

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Accuracy and Sensitivity of Commercial PCR-Based Methods for Detection of Salmonella enterica in Feed

Cited by 43 publications

References 37 publications

A lab-on-a-chip system with integrated sample preparation and loop-mediated isothermal amplification for rapid and quantitative detection of Salmonella spp. in food samples

A lab-on-a-chip system with integrated sample preparation and loop-mediated isothermal amplification for rapid and quantitative detection of Salmonella spp. in food samples

Detection of Foodborne Bacterial Pathogens from Individual Filth Flies

Lag Phase of Salmonella enterica under Osmotic Stress Conditions

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