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Staphylococcal food poisoning is a common foodborne disease caused by the ingestion of staphylococcal enterotoxins (SEs) produced mainly by enterotoxigenic strains of Staphylococcus aureus. To date, 21 SEs and/or enterotoxin-like types have been identified, several of which represent a potential hazard for consumers. To protect consumer health and to reduce the amount of SE-contaminated food entering the market, European Union legislation regulating food safety requires testing for SEs. The Italian National Reference Laboratory organized a ring trial to test technical and analytical proficiency in the national network of official food laboratories. Twenty-four laboratories took part, and each received and analyzed 24 blind dairy samples. Reproducibility of the results from the laboratories was assessed by the Cohen k index, and accuracy (sensitivity and specificity) was evaluated according to the International Organization for Standardization definition (ISO 16140:2003). Trial results revealed partially satisfactory agreement: 254 of 276 possible paired participants (92%) reached a k value >0.60, which is conventionally recognized as satisfactory. Accuracy was deemed satisfactory; 100% sensitivity and 100% specificity were achieved by 22 and 18 of the 24 laboratories, respectively.

Selling fish products as fresh when they have actually been frozen and thawed is a common fraudulent practice in seafood retailing. Unlike fish products frozen to protect them against degenerative changes during transportation and to extend the product's storage life, fish intended for raw consumption in European countries must be previously frozen at -20° C for at least 24 h to kill parasites. The aim of this study was to use histological analysis to distinguish between fresh and frozen-thawed fish and to evaluate this method for use as a routine screening technique in compliance with the requirements of European Commission Regulation No. 882/2004 on official food and feed controls. Method performance (i.e., accuracy and precision) was evaluated on tissue samples from three common Mediterranean fish species; the evaluation was subsequently extended to include samples from 35 fish species in a second experiment to test for method robustness. Method accuracy was tested by comparing histological results against a "gold standard" obtained from the analysis of frozen and unfrozen fish samples prepared for the study. Method precision was evaluated according to interrater agreement (i.e., three laboratories with expertise in histopathology in the first experiment and three expert analysts in the second experiment) by estimating Cohen's kappa (and corresponding 95 % confidence intervals) for each pair of laboratories and experts and the combined Cohen's kappa for all three experts and laboratories. The observed interrater agreement among the three laboratories and the three experts indicated high levels of method accuracy and precision (high sensitivity and specificity) and method reproducibility. Our results suggest that histology is a rapid, simple, and highly accurate method for distinguishing between fresh and frozen-thawed fish, regardless of the fish species analyzed.

The bovine spongiform encephalopathy epidemic is thought to have occurred as a consequence of feeding prion-infected material to cattle. To avoid the risk of bovine spongiform encephalopathy diffusion, the European Commission (Directive 2003/126/EC) established an official method to detect the presence of animal-derived constituents in feedstuffs, using microscopic examination. This method allows easy identification of bone fragments among other animal constituents. The analysis is based on morphological conformation of the fragments and their characterization (mainly of the shape of lacunae) to discriminate among mammalian, poultry, and fish tissues. The aim of this study was to assess the performances of nine European laboratories through a ring trial of the official microscopic method, and to calculate accuracy and reproducibility of the method. In general the reproducibility of the microscopic method was very good (kappa overall = 0.83), with a high sensitivity for all laboratories. Concerning the analysis on the different animal-derived constituents, the results show values of sensitivity with large variability between fish and poultry or mammal. It was generally more difficult to discriminate between mammalian and poultry tissues than fish tissue.

Bovine spongiform encephalopathy is a prion disease of ruminants that was first recognized in 1986 in the United Kingdom. Early in the epidemic, it became obvious that the presence of meat and bone meal in feed rations was a common factor in all bovine spongiform encephalopathy cases. The first ban of derived animal proteins in feed was enforced in Europe in 1994 and implemented by Regulation 999/2001 that prohibited the feeding of animal-derived protein to farm animals. The only official method currently accepted by the European Union Commission for test for the presence of animal-derived proteins in feedstuffs is feed microscopy. In Italy, monitoring of feedstuff safety is provided by both the Ministry of Health and the Ministry of Agriculture. The quality of official control, usually assessed by verifying the reproducibility and the accuracy of the testing method, is of fundamental importance for all laboratories and institutions using these results for comparative purposes. The aims of this study were to assess the reproducibility of the official method over all the Italian surveillance network and to provide a model for evaluating the performance of the monitoring system. The accuracy of the identification of the animal class of derived protein detected (avian, mammalian, or aquatic organism) was assessed. The interlaboratory agreement within the overall network reached 0.97 (95% confidence interval of 0.95 to 0.98) for determining the presence or absence of animal-derived proteins (e.g., for mammalian, avian, or aquatic species), and specificity of the identification of the animal class indicated that fish proteins are more easily recognized than are avian or mammalian proteins.