Experimental evaluation of different precision criteria applicable to microbiological counting methods.
The dispersion of microbiological counting measurements, when repeating the analysis on the same material both within a laboratory (repeatability) and between laboratories (reproducibility) can be characterized by the organization of interlaboratory studies, where several sets of identical test materials are sent to several laboratories. Using the example of data generated by an interlaboratory study on enumeration of Listeria monocytogenes in foods by the standardized reference method (colony-count technique), 2 types of robust estimators of reproducibility standard deviations, based on the median, were examined, in comparison with the classical estimators, based on the mean. Experimental evaluation indicated that the 3 approaches gave consistent results for most of the combinations. The usual log10 transformation of the enumeration results was also questioned before these calculations were conducted.
Agence Française de Sécurité Sanitaire des Aliments-Laboratoire d'Etudes et de Recherches sur la Qualité des Aliments et sur les Procédés Agro-Alimentaires, 23 Avenue du Général De Gaulle, 94 706 Maisons-Alfort, France. b.lombard@afssa.fr
Bertrand
B
Lombard
Marie
M
Cornu
Cecile
C
Lahellec
Max H
MH
Feinberg
D000465:Algorithms; D001431:Bacteriological Techniques; D002611:Cheese / Q000382:microbiology; D015169:Colony Count, Microbial; D004531:Eggs / Q000382:microbiology; D005069:Evaluation Studies as Topic; D005506:Food Contamination; D005516:Food Microbiology; D007753:Laboratories; D008089:Listeria monocytogenes; D008829:Microbiology; D015233:Models, Statistical; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity