P-001. Pathogen Detection in Food Microbiology Laboratories: An Analysis of Proficiency Test Performance, 1999 - 2007

D. C. Edson;
American Proficiency Inst., Traverse City, MI.

Background: For U.S. clinical laboratories, proficiency testing has evolved into an essential component of quality assurance programs. These laboratories are regulated by a federal law, CLIA 1988, which requires participation in an approved PT program. Food laboratories are not subject to these same requirements, but as public concern over food safety increases and more food laboratories seek accreditation, participation in PT programs is increasing as well. American Proficiency Institute, a federally approved proficiency testing provider serving the clinical laboratory market, also offers PT programs for the food industry. We studied the performance characteristics and trends of these sites over a nine year period from 1999 to 2007. Our objective was to assess whether laboratories could reliably detect or rule out contamination with 4 common food pathogens: E coli O157:H7, Salmonella spp, Listeria monocytogenes, and Campylobacter spp. Methods: False positive and false negative rates for selected food microbiology pathogens were recorded from proficiency testing results submitted in three test events per year over nine years. <b>Results</b>: Performance accuracy for food microbiology pathogens is problematic. The average percentage of false negative results over the 9 years was 6.0% for Salmonella spp, 7.3% for L monocytogenes, 8.0% for E coli O157:H7, and 15.3% for Campylobacter spp. The average percentage of false positive results was 0.4% for Campylobacter spp, 1.7% for L monocytogenes, 2.3% for E coli O157:H7, and 4.2% for Salmonella spp. Conclusion: In this retrospective study, food laboratories routinely fail to detect pathogens in food samples more than 5% of the time. The data suggest that: 1) laboratories are more proficient at ruling out than detecting the presence of pathogens, and 2) performance has not improved during the past 9 years.