False negative results in food laboratories are concerning

The study was conducted by the American Proficiency Institute (API)

The accuracy of food microbiology laboratories when detecting or ruling out the presence of E.coli 0157:H7, Salmonella spp., Listeria monocytogenes and Campylobacter jejuni remains concerning, according to a study.

The analysis of nearly 40,000 proficiency test results over the past 14 years found that false negative and false positive results are found on a routine basis.

A false negative is when pathogens are not detected but are found in the food and a false positive report shows the pathogens are there when they are not.

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

"There is concern when laboratories report that pathogens are not found in a food sample, when in fact they are there," explained 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."

Study details: The study was conducted by the American Proficiency Institute (API) which is a private institute that supplies proficiency testing programs for food laboratories and clinical laboratories. Currently, food laboratories are not required to assess the accuracy or quality of their tests, said the institute. API offers proficiency testing (PT) which looks for the presence or absence of a substance in a qualitative test, and it may require an enumeration response, or quantitative test.

The Food Safety Modernization Act addressed model laboratory standards and laboratory accreditation as 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, said API.

The research was presented as part of the 2013 General Meeting of the American Society for Microbiology held this month in Denver, Colorado.

Source: Food Quality News