[Rapid enumeration of bacteria in foods using Direct Epifluorescent Filter Technique.]

The aim of this study was to test the feasibility of a method designed for the rapid counting of bacteria in various kinds of foods i.e. the Direct Epifluorescent Filter Technique (DEFT). With frozen vegetables, total bacteria count found in 103 samples (n = 103) is significantly correlated (r = 0.87) with the standard method (Plate count agar - PCA); with raw meat (n = 14), even if the DEFT seems to overestimate the total bacteria populations, the correlation with PCA is higher (r = 0.99). However, for this last kind of food, an extraction of fat is necessary. When poultry products are examined, the correlation obtained with neck skin samples is unsatisfactory (r = 0.42). As far as the enumeration of more specific bacteria populations is concerned, e.g. the Enterobacteriaceae in frozen spinach (n = 28), a poor correlation is observed with the standard procedure (r = 0.57). However, better results are obtained with the enumeration of Staphylococcus aureus in raw meat (r = 0.8 to 0.95, n = 17). Good agreement is obtained between visual counting (r = 0.95) and semi-automated image analyser counting.