Among the various types of DNA-based rapid methods, polymerase chain reaction (PCR) has been used to detect pathogens for more than 30 years. It can detect foodborne pathogens such as Salmonella, Listeria, Listeria , and Cronobacter. PCR heating and cooling cycles to cause DNA melting and replication.
Here’s how PCR works: The process uses heat to separate the two DNA strands, after which the temperature is lowered and primers bind to the DNA. Repeated cycles of heating and cooling, combined with the addition of primers at each step, amplify the DNA for the detection of pathogens. PCR is currently the most widely established method in the world and is used in Hygiena’s BAX.
Loop-mediated isothermal amplification (LAMP) is a technique that also uses DNA-based testing. LAMP is used in the 3M™ Molecular Detection System, which combines isothermal DNA amplification and bioluminescence detection.
Using methods similar to PCR, technicians immerse the sample in primers that search for DNA from Salmonella, Campylobacter, or other specific pathogens. If DNA is present in the sample, the primer makes copies and amplifies that DNA. By amplifying the target DNA, it creates a signal—in the form of light—that is strong enough for the instrument to detect.
However, LAMP from PCR several ways. It uses four to six primers to recognize six distinct regions of DNA or RNA, whereas PCR two primers to recognize two regions. The primers in LAMP DNA strand displacement and cause the end of the DNA strand to form a loop. This structure is the basis for amplification and enables the exponential accumulation of additional double-stranded DNA.
PCR requires many cycles of heating and cooling to amplify the target—and that requires more complex equipment. LAMP isothermal amplification, which means it only needs to be heated to a single temperature—60 to 65 degrees Celsius. This means fewer steps for the technician and smaller, simpler equipment. LAMP also LAMP bioluminescence to detect the pathogen, so the equipment can detect amplification of the target during the reaction in as little as 15 minutes.
Which method is best?
Both technologies have their pros and cons, but the deciding factor often comes down to cost and the type of samples to be analyzed.
| LAMP | PCR |
| Uses an isothermal reaction (60 to 65 °C) | Uses a cycling reaction (multiple heating and cooling cycles) |
| Uses 4 to 6 primers and recognizes 6 to 8 distinct regions on the target DNA Loop primers accelerate the reaction and increase sensitivity by providing additional recognition sites | Uses 2 primers, detects 2 regions of target DNA |
| Bioluminescence makes detection easy | The use of probes adds specificity and facilitates detection |
| Simpler, more compact equipment—no moving parts or cooling fans; easier to maintain and clean; portable | More complex, larger equipment – requires periodic calibration, moving parts, and cooling fans; fluorescence requires a light source, filters, and detectors; less portable |
| Streamlined protocols – similar for all targets, with minimal steps | More varied protocols, but the range of applications is broader compared to LAMP |