FDA Food Microbiology Test Methods

Foodborne pathogens account for nearly 76 million illnesses annually in the United States, reports science writer Lori Valigra at FoodQuality.com. The U.S. Food and Drug Administration tests food for pathogens--disease-producing agents--before it can enter stores. The main food categories tested by the FDA include ready-to-eat foods, fermented foods, raw meat, poultry, seafood and eggs. According to the USDA Food Safety and Inspection Service (FSIS), Listeria monocytogenes, Escherichia coli and Salmonella are three major concerns when testing for food pathogens.

PCR

• DNA sequencing to observe microbe count

  A polymerase chain reaction is a process of genetic manipulation, where the microbe to be tested has its DNA multiplied and counted. From a sample of food, the microbes present are isolated and the DNA taken out. The DNA of the dangerous bacterium or microorganism is then replicated until there is enough of it to be studied. DNA-based identification provides an accurate and specific count of microbes within food samples. The FDA has defined allowable results to determine whether a tested item is safe for the public.

BAX

• DuPont has developed a more recent development in food microbe testing, based on 13 PCR evaluations that can target up to nine microbes. The BAX system can check for specific pathogens after each cycle, making it much more thorough and efficient than traditional PCR testing, claims DuPont. Valigra provides an example for BAX tests with E. coli, an indicator organism that the FSIS says can help identify sanitary conditions of a food-producing establishment. Results "are available in about 55 minutes, compared to 3.5 hours" for the traditional PCR method, writes Valigra.

Hepatitis A Testing

• Hepatitis A is a disease spread by the handling or eating of food that has been in contact with fecal material. A specific version of the PCR test evaluates the levels of hepatitis A virus in a sample, allowing for quick, up-to-date results. According to Microbac.com, as hepatitis A is an RNA (ribonucleic acid) virus, rather than a DNA virus, the PCR test uses the total RNA taken from the original sample in order to make DNA for identification.