Desiccation and heat tolerance of Enterobacter sakazakii.

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.

Comparative evaluation of two methods of enumerating enterococci in foods: collaborative study.

Two methods of enumerating enterococci in foods were compared in a collaborative study. Thirteen laboratories tested four blind duplicate samples containing different levels of enterococci and two negative control samples. Freeze-dried mixtures of bacteria were used as simulated food samples.

Freeze-dried mixed cultures as reference samples in quantitative and qualitative microbiological examinations of food.

Two simulated food samples in the form of mixtures of bacteria, freeze-dried in small glass vials, were tested for their suitability as reference materials in food microbiology. Stability and homogeneity of the samples were assessed during a 1 year period when stored at 2-6 degrees C. Samples were examined for aerobic plate counts, coliform counts, Staphylococcus aureus, Clostridium perfringens, Bacillus cereus, enterococci, yeasts and salmonellas.

Laboratory performance in a food microbiology proficiency testing scheme.

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.