Aims: Enterobacter sakazakii is an opportunistic pathogen which has been isolated at low levels from powdered infant formulas. This study was performed to demonstrate that Ent. sakazakii is not particularly thermotolerant, but can adapt to osmotic and dry stress. Methods and Results: We determined the heat, osmotic and dry stress resistance of Ent. sakazakii. The D-value at 58°C ranged from 0AE39 to 0AE60 min, which is comparable with that of other Enterobacteriaceae, but much lower than reported previously (Nazarowec-White and Farber 1997, Letters in Applied Microbiology 24: 9-13). However, stationary phase Ent. sakazakii cells were found to be more resistant to osmotic and dry stress than Escherichia coli, Salmonella and other strains of Enterobacteriaceae tested. Further analysis indicated that the dry resistance is most likely linked to accumulation of trehalose in the cells. Conclusions:The high tolerance to desiccation provides a competitive advantage for Ent. sakazakii in dry environments, as found in milk powder factories, and thereby increases the risk of postpasteurization contamination of the finished product. Significance and Impact of the Study: Understanding of the physiology and survival strategies of Ent. sakazakii is an important step in the efforts to eliminate this bacterium from the critical food production environments.

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Management of microbiological food safety is largely based on good design of processes, products and procedures. Finished product testing may be considered as a control measure at the end of the production process. However, testing gives only very limited information on the safety status of a food. If a hazardous organism is found it means something, but absence in a limited number of samples is no guarantee of safety of a whole production batch. Finished product testing is often too little and too late. Therefore most attention should be focussed on management and control of the hazards in a more proactive way by implementing an effective food safety management system. For verification activities in a food safety management system, finished product testing may however be useful. For three cases studies; canned food, chocolate and cooked ham, the relevance of testing both of finished products and the production environment is discussed. Since the level of control of different processes can be largely different it is beneficial if the frequency of sampling of finished products and production environments would be related to the associated human health risk, which can be assessed on the basis of risk assessment and epidemiological data

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Results from two shipments in a proficiency testing scheme in which almost 200 food microbiology laboratories participated are summarized. Freeze-dried mixtures of bacteria were used as simulated food samples. Four and six samples, respectively, were examined. The statistical procedures used to evaluate the performance of participating laboratories are described. It is shown that laboratories which had been in the scheme for a long time perform, on average, better than those that had been in the scheme for a short time. The former laboratories produced fewer false and outlying results, and were more accurate and precise in their determinations.