A Look at the American Proficiency Institute and Pathogen Detection in Food Microbiology

A recent study published by the American Proficiency Institute (API), one of the largest proficiency testing providers in the world, has provided a new perspective on some of the troubles facing the Food Quality Industry. The objective of this study was to assess laboratories' ability to detect or rule out contamination with four common food pathogens: E. coli O157:H7, Salmonella spp., Listeria monocytogenes, and Campylobacter spp. In the study API examined qualitative proficiency data collected over a period of eleven years. API found the average percentage of false negative results was consistently above 5.0% for all four pathogens throughout the study period, Campylobacter spp. being the most likely to be missed. These results suggest that food testing laboratories often fail to detect the presence of these pathogens in real food specimens.

We had the privilege of speaking with Daniel Edson M.S., MT(ASCP), President of API and one of the authors of this study, to gain some insight regarding their findings and how this information can be used to identify opportunities for improvements within the Food Quality Industry.

Microbiologics: What could be causing laboratories to fail at detecting pathogens?

Edson: Research in clinical microbiology laboratories has linked poor performance to failure in following recommended practices for culturing and identifying pathogens and to inadequate staffing and insufficient training of personnel. While poor performance in food testing laboratories has not been extensively researched, investigators have mentioned issues such as insufficient incubation time, incorrect incubation temperature, and improper plating of media. Laboratories may also fail to a detect pathogen when its concentration is low or it is an atypical strain.

Microbiologics: How accurately do proficiency test samples reflect performance with real food samples?

Edson: It's difficult to determine how performance with proficiency testing samples reflects performance with real food specimens for several reasons. Personnel may analyze proficiency test samples more carefully than they would analyze real food samples. In addition, proficiency testing measures only the analytical phase of the testing process. Pre-analytical errors in collecting, transporting and processing specimens, or post analytical errors in reporting results that could occur with real food specimens may not be detected. Finally, because proficiency test samples are more homogenous than real food samples and contain laboratory attenuated strains of bacteria, performance with these samples could be better than performance with real food samples. When all of these factors are considered, it seems likely that the rate of false negative results with real food samples is even greater than our study indicates. If so, this is clearly a serious public health issue that demands resolution.

Microbiologics: What is your viewpoint of current food testing regulations?

Edson: Comparatively, clinical and pharmaceutical testing laboratories are much more regulated than food testing laboratories. Public health is directly affected by all of these types of laboratories, so shouldn't they be equally governed? The Food Quality industry is in the middle of a major overhaul. It's likely that tighter government regulations will be enforced in the future. Food testing laboratories can be pro-active to these changes and avoid obstacles later, by strengthening their Quality Control and Assurance programs in advance.

Microbiologics: What are some of your tips for improving pathogen detection?

Edson: Here are a few quick suggestions for improving pathogen detection. Ensure personnel are adequately trained. Follow proper procedures. When applicable, base procedures on guidelines set forth by panels of scientific experts such as AOAC, BAM, USP, CMMEF and SMEDP. Maintain equipment and use it properly to ensure good bacterial growth. Confirm that materials such as diluents, reagents and media are correctly prepared and properly stored. Ensure that suitable techniques are used to prepare primary and analytical test samples. Perform quality control on reagents, media and equipment as recommended by manufacturers. Finally, always investigate unsatisfactory proficiency test results.

Microbiologics: How does API help food testing laboratories improve their performance?

Edson: Proficiency testing identifies opportunities for improvement. When a laboratory is struggling in a particular area of the testing process, we offer one-on-one technical assistance to help them perform better. American Proficiency Institute is one of the largest proficiency testing providers in the world with over 600 food laboratory customers in 30 countries. Visit www.foodpt.com for more information.

Microbiologics: Thank you Mr. Edson for sharing your expertise with the Microbiologics® Magnified readers.

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Microbiologics offers more than 750 different microorganism strains including such species as H₂S- negative Salmonella, non-toxigenic Escherichia coli O157:H7, and Listeria monocytogenes with the Act A gene removed.

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