Food Protection Trends - July/August 2024 - 307

MITIGATION
Laboratory quality systems are designed to ensure that test
results are trustworthy (29). Reputable modern laboratories
are usually accredited to ISO 17025:2017 (14), which sets
the expectation for elements of a laboratory quality system,
including the following:
* Use of appropriate methods and standard operating
procedures
* Use of quality control procedures to monitor and assess
the accuracy and precision of test results
* Maintenance and calibration of laboratory equipment
* Use of appropriate documentation and recordkeeping
procedures
* Training and competence of laboratory staff (3, 11)
* Use of proficiency testing programs to assess the
laboratory's performance relative to other laboratories
(11, 22)
Successfully implemented laboratory quality systems ensure
consistent and reliable laboratory performance and help
to eliminate mistakes and operational errors. They cannot
overcome the inherent variability of microorganisms and
fundamental limits of detection technologies, but they can,
at least, make sure that the limits of performance are understood
and documented. Each time an investigation of ambiguous
results and discrepancies identifies a root cause, the
relevant elements of the quality system should be reviewed
and, if necessary, modified to capture the learning and reduce
the chance of seeing the same issue again.
CONCLUSIONS
There are many potential causes of discrepancies and
ambiguous results. We have attempted to show the most
REFERENCES
1. Abdel Massih, M., V. Planchon, M. Polet, K.
Dierick, and J. Mahillon. 2015. Analytical
performances of food microbiology
laboratories-Critical analysis of 7 years of
proficiency testing results. J. Appl. Microbiol.
120:346-354.
2. Anonymous. 2023. Appendix J: AOAC
International Methods Committee guidelines
for validation of microbiological methods for
food and environmental surfaces, p. AJ-1-
AJ-21. In G. W. Latimer, Jr. (ed.), Official
methods of analysis of AOAC International.
AOAC International, Rockville, MD.
3. Awuchi, C. G. 2023. HACCP, quality,
and food safety management in food
and agricultural systems. Cogent Food &
Agriculture 9:2176280.
4. Basu, M. 2015. 28 years for Salmonella:
Peanut exec gets groundbreaking
sentence. Available at: https://www.cnn.
com/2015/09/21/us/salmonella-peanutexec-sentenced/index.html.
Accessed 28
November 2023.
5. Brown, M. S., P. M. Bird, S. Brunelle, W.
E. Chaney, C. A. Kennett, J. D. Legan, R.
D. Maus, L. Post, and S. Pollard. 2021.
Alternative approaches for qualitative
microbiological method matrix additions.
Food Prot. Trends 41:152-162.
6. Carlin, C. R., J. Liao, D. Weller, X. Guo,
R. Orsi, and M. Wiedmann. 2021. Listeria
cossartiae sp. nov., Listeria immobilis sp. nov.,
Listeria portnoyi sp. nov. and Listeria rustica
sp. nov., isolated from agricultural water
and natural environments. Int. J. Syst. Evol.
Microbiol. 71:004795.
7. Cone, R. W., A. C. Hobson, and M. L. Huang.
1992. Coamplified positive control detects
inhibition of polymerase chain reactions.
J. Clin Microbiol. 30:3185-3189.
8. Cooley, M. B., M. Jay-Russell, E. R. Atwill,
D. Carychao, K. Nguyen, B. Quiñones, R.
Patel, S. Walker, M. Swimley, E. PierreJerome,
A. G. Gordus, and R. E. Mandrell.
2013 Development of a robust method for
isolation of Shiga toxin-positive Escherichia
coli (STEC) from fecal, plant, soil and water
samples from a leafy greens production
region in California. PLoS ONE 8:e65716.
9. Cox, N. A., M. E. Berrang, S. L. House,
A. Hinton, Jr., J. E. Line, and L. T.
Wiggins. 2020. Detection of multiple
naturally occurring Salmonella serotypes
from commercial broiler carcasses with
conventional methods. J. Food Saf.
40:e12761.
10. Edson, D., S. Empson, and L. D. Massey. 2009
Pathogen detection in food microbiology
laboratories: An analysis of qualitative
proficiency test data, 1999-2007. J. Food Saf.
29:521-530.
11. Emons, H., A. Held, and F. Ulberth. 2006.
Reference materials as crucial tools for
quality assurance and control in food analysis.
Pure Appl. Chem. 78:135-143.
12. Fakruddin, M., K. S. B. Mannan, and S.
Andrews. 2013. Viable but nonculturable
bacteria: Food safety and public health
perspective. Int. Scholarly Res. Notices,
2013:703813.
common causes and approaches that can be used to investigate
them. Once root causes are identified, procedures can
be put in place to prevent or reduce the risk of reoccurrence,
and these steps become part of the normal laboratory quality
system.
Much of the stress caused by discrepancies and ambiguous
results arises from the need to take some action, and the
action may be hard to determine if the result is not clear. In
this context, the greatest consequences arise with pathogen
detections. FDA requires cultural confirmation of its own
results for proof of viability and source tracking. Perhaps this
is why it is widely believed that results from rapid screening
platforms must be confirmed by culture. However, FDA
and ISO standards do not preclude industry from accepting
an instrumental presumptive result and taking corrective
action without cultural confirmation, and many pathogen
test users take this approach. FDA's concern is ensuring that
adulterated foods do not go into commerce. In a guidance
for industry document (34), FDA states, " you should not
have to perform another test or obtain a cultural isolate
from a presumed positive sample if you choose to not ship
the food based on the presumptive positive result. " The
safest approach is to act on the presumptive result, even if
confirmation and identification are done in parallel to gain
additional information.
ACKNOWLEDGMENTS
The authors thank Robert Orsi of Midwest Laboratories
for the design work on Figures. 1 and 2.
July/August Food Protection Trends 307
https://www.cnn.com/2015/09/21/us/salmonella-peanut-exec-sentenced/index.htm https://www.cnn.com/2015/09/21/us/salmonella-peanut-exec-sentenced/index.htm https://www.cnn.com/2015/09/21/us/salmonella-peanut-exec-sentenced/index.htm
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