Pathogen identification by selective cultivation uses metabolic features and phenotypes to pinpoint a contamination. This procedure is not only time-consuming but also susceptible to inconclusive results due to the ever-changing nature of bacteria. PCR-based pathogen detection uses a barcode unique to each strain: its DNA. A DNA sequence highly specific for the designated pathogen is amplified in an exponential matter, accumulation of specific amplicons is monitored through an increase in fluorescence signal. The high specificity of PCR-based pathogen detection allows to reliably distinguish between e.g. non-pathogenic Escherichia Coli and EPEC.
PCR-based pathogen detection also allows for processing hundreds of samples in parallel without additional expenses. The reaction setup is easy to scale-up and can be automatized if required.
The most common means of detection for pathogen contaminants in food are either ELISA-based methods or selective cultivation of microorganisms. Realtime-PCR is a reasonable addition complementing weak points of conventional assays. Pathogen detection with real-time PCR is highly sensitive and specific due to the amplification of pathogen-specific DNA sequences. It is less labour-intensive, faster and – not least – safer to work with as only purified DNA is used for the screening and pathogen cultivation can be reduced to a minimum.
Figure 1 Comparison of different methods of pathogen detection with focus on expenditure of time. Realtime-PCR delivers results faster, more sensitive and less labour-intensive than conventional approaches.
The PhoenixDx series is designed to provide highly specific and reliable results. Each kit is verified for pathogen specificity and reliability on multiple levels.
- detects a highly pathogen-specific target DNA sequence with carefully designed primers and probes
- detects target sequences that have been evaluated for pathogen specificity with bioinformatical means
- has been tested for specificity in real experiments against non-related pathogen DNA
- includes a PCR positive control (PPC) that helps to detect PCR inhibition and exclude false negatives
PhoenixDx Listeria monocytogenes was used to analyse a human DNA sample and DNA samples of several other pathogens such as S. enterica. A positive signal was only obtained for L. monocytogenes DNA.
Figure 2 Evaluation of PhoenixDx Listeria monocytogenes on L. monocytogenes DNA (blue) and other pathogen DNA (orange).
PhoenixDx is a highly specialized tools to detect minimal presence of pathogen DNA. As less as 2 copies of the target sequence are sufficient for a positive signal. To ensure a stable workflow, PhoenixDx can detect DNA of interest over a broad concentration range.
Figure 3 Detection of bacterial target DNA with PhoenixDx Gram-positiv from 66.000 to 8 target copies.
|Product||Channel Pathogen||Channel PPC||Details & Order|
|PhoenixDx Salmonella spp.||FAM||Cy5||see here|
|PhoenixDx Listeria monocytogenes||FAM||Cy5||see here|
|PhoenixDx Legionella pneumophila||FAM||Cy5||see here|
|PhoenixDx Clostridium difficile (Toxin B)||FAM||Cy5||see here|
|PhoenixDx Helicobacter pylori||FAM||Cy5||see here|
|PhoenixDx Staphylococcus aureus||FAM||Cy5||see here|
|PhoenixDx Campylobacter spp.||FAM||Cy5||see here|
|PhoenixDx Campylobacter jejuni||FAM||Cy5||see here|
|PhoenixDx Campylobacter coli||FAM||Cy5||see here|
|PhoenixDx Shigella spp.||FAM||Cy5||see here|
|PhoenixDx Yersinia enterocolitica||FAM||Cy5||see here|
|PhoenixDx EPEC||FAM||Cy5||see here|