Safety-related properties of staphylococci isolated from food and food environments

Aims: To test some safety-related properties within 321 staphylococci strains isolated from food and food environments. Methods and Results: The isolates were identified as Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus, Staphylococcus pasteuri, Staphylococcus sciuri, Staphylococcus warneri and Staphylococcus xylosus. Decarboxylase activity was quite common for the various Staphylococcus spp., and tyrosine was the most frequently decarboxylated amino acid. The frequency of antibiotic resistance was highest in Staph. pasteuri and Staph. xylosus. Several of the isolates were tolerant to QAC compounds, and in some cases, QAC tolerance was present in antibiotic-resistant strains. Most of the strains displayed moderate to high adhesion rates to stainless steel and Teflon. The strains that readily formed biofilms belonged to the species Staph. aureus, Staph. epidermidis and Staph. pasteuri. Conclusions: An high incidence of some safety hazards was found within the staphylococcal strains of food origin tested in this study. In particular, amino acid decarboxylase activity and biofilm-forming ability were common within strains, and antibiotic resistance and tolerance to QAC-based compounds occurred frequently as well. These characteristics are an important safety concern for food industry. Significance and Impact of the Study: This work gives a first picture of safety hazards within staphylococcal species isolated from food environments. The presence of disinfectant-resistant staphylococci is a concern because resistance can be genetically transferred between the various Staphylococcus species. This could lead an increase and spread of resistant enterotoxic staphylococci and . or pathogenic staphylococci.