Study Raises Concerns Over Food Laboratory Accuracy

DENVERNew research presented at the 113th General Meeting of the American Society for Microbiology raises concerns over food laboratory accuracy after it found food microbiology laboratories continue to submit false negative results and false positive results on a routine basis.

A retrospective study of nearly 40,000 proficiency test results over the past 14 years examined the ability of food laboratories to detect or rule out the presence of Escherichia coli O157:H7, Salmonella, Listeria monocytogenes and Campylobacter.

The study found that, on average, food laboratories report false negatives of 9.1% for Campylobacter and 4.9% for Salmonella. The false positive rate, on average, is 3.9% for Salmonella, and 2.5% for both E. coli and Listeria monocytogenes.

There is concern when laboratories report that pathogens are not found in a food sample, when in fact they are there," said Christopher Snabes, lead author on the study. This is known as a false negative. Similar concerns arise when a laboratory reports a false positive suggesting that pathogens are in the food sample, when indeed they are not."

Currently, food laboratories are not required to assess the accuracy or quality of their tests. Laboratories that utilize proficiency testing are doing so voluntarily. Proficiency testing is an objective means for measuring laboratory accuracy.

Improved accuracy in our nations food laboratories will lead to a safer food supply," Snabes said.

The Food Safety Modernization Act (FSMA) passed in 2011 included sweeping changes to the countrys food safety requirements.  Model laboratory standards and laboratory accreditation are addressed as important components of the law. Once rules are promulgated, it is anticipated that all food laboratories will need to ensure that their personnel, and the test methods they use, are in compliance with the law. Yet, food laboratories may start using proficiency testing now to help ensure a safer food product.