ORIGINAL ARTICLE Safety-related properties of staphylococci isolated from food and food environments M. Marino, F. Frigo, I. Bartolomeoli and M. Maifreni Department of Food Science, University of Udine, Udine, Italy Introduction Staphylococci are ubiquitously distributed in nature and are frequently isolated from food and environmental sources. Several species, such as Staphylococcus aureus, Staphylococcus saprophyticus and Staphylococcus epidermi- dis, can cause disease in humans (Rodriguez et al. 1996). Staphylococcus aureus is a foodborne pathogen that is considered one of the world’s leading causes of disease outbreak related to food consumption. Contaminated food, such as various meat products, poultry, eggs, dairy, seafood, as well as breads and bakery products, often contains staphylococcal enterotoxins (SE), which often cause food-related illness (Greig et al. 2007). Investiga- tions into retail meals have concerned only incidence of Staph. aureus, even if other staphylococcal species can occur in food (Mounier et al. 2006; Simeoni et al. 2008). Although SE production is the leading cause of food- related disease by staphylococci, other biophysical and biochemical features, such as amino acid decarboxylase activity, adhesion and biofilm formation, and disinfectant and antibiotic resistance can contribute to pathogenicity and should be further studied. While some safety- associated characteristics, such as toxin production and Keywords antibiotics, biofilm, disinfection, resistance, staphylococci. Correspondence Marilena Marino, Department of Food Science, University of Udine, via Sondrio 2 ⁄ A, 33100 Udine, Italy. E-mail: marilena.marino@uniud.it 2010 ⁄ 1681: received 22 September 2010, revised 2 November 2010 and accepted 15 November 2010 doi:10.1111/j.1365-2672.2010.04909.x Abstract 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. Decar- boxylase 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 toler- ance was present in antibiotic-resistant strains. Most of the strains displayed moderate to high adhesion rates to stainless steel and Teflon Ò . 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 con- cern 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. Journal of Applied Microbiology ISSN 1364-5072 550 Journal of Applied Microbiology 110, 550–561 ª 2010 The Society for Applied Microbiology ª 2010 The Authors