The presence of Listeria spp. in chicken drumsticks, wings, breasts, and livers taken from a poultry processing plant was investigated. The poultry pieces found to be most contaminated were drumstick meat and skin, with 96% of samples shown to contain Listeria spp. Drumsticks contained the highest number of Listeria spp., with counts in many cases exceeding 3 log CFU/g for skin and muscle. Samples were also taken from various surfaces in the processing plant, where the most contaminated areas were found to be in the final stages of meat processing. Three samples were positive for Listeria spp. immediately after washing and disinfection had taken place. The results suggest that drumsticks are responsible for a large amount of the contamination of chicken carcasses, and that the surfaces that come into contact with these pieces of meat play an important role in spreading Listeria spp. Disinfection procedures used by this processing plant do not effectively control Listeria spp.

Escherichia coli 0157:H7 STCC 4076, E. coli 0157:H7 STCC 4267 and E. coli STCC 515 were cultured alone or in combination with Pseudomonas fluorescens STCC 378 at 7C or 25C in 10% reconstituted skimmed milk. Culture pH and bacterial population densities were monitored over 40 days. Both E. coli 0157:H7 strains grew well afrer 40 days of incubation at 7C with final pH values between 4.86-4.53. At 25C, both E. coli 0157:H7 strains grew during 20 days with jinal pH values of 4.00-4.14. m e pH of the different cultures of this study decreased more at 25C than at 7C. The results suggest that P.fluorescens may inhibit the growth of the other bacteria present in milk at 7C, but this inhibition is weak. In contrast, the growth of E. coli 0157:H7 strains in the presence of P. fluorescens appears to be slightly enhanced during most of the incubation period at 25C.

Cebrero cheese is traditionally manufactured from raw cow's milk in the Cebrero mountains of Galicia (NW Spain). We report determinations of pH and aw, and counts of total aerobic bacteria, psychrotrophs, Enterobacteriaceae, Escherichia coli, coagulase‐positive Staphylococcus aureus, Listeria, molds and yeasts, in 49 samples. E. coli count exceeded the level permitted by Spanish legislation in 51% of samples. S. aureus count exceeded the level permitted in 20% of the samples. In one sample, with pH 5.06, two species of Listeria (L. monocytogenes and L. seeligeri) were detected. Although the pH of this cheese is fairly low, it does not appear to be sufficient to prevent the occurrence of certain pathogenic microorganisms.

The behaviour of two Listeria species (L. monocytogenes and L. innocua) during the elaboration and ripening of Arzua's Cheese from Galicia (North-West of Spain) has been studied. The effect of sodium sorbate against these microorganisms was also evaluated. During the elaboration most of the tested microorganisms were entrapped into the curd. Listeria populations decreased during 55 days of ripening. Populations were always higher into the cheese than in the surface. No significant differences were found between Listeria populations in the surface of cheese made with or without addition of potassium sorbate.