The ability of Staphylococcus aureus to form biofilms provides it an important virulence factor. The bacteria surrounded by a biofilm are more difficult to be removed than those in the planktonic form and, once a biofilm is established, it becomes a source of contamination for products and surfaces. In vitro studies indicated that bacterial strains growing in biofilms may become 10-1,000 times more resistant to the effects of sanitizers than the same strain in planktonic form. Moreover, biofilms are capable of releasing planktonic cells from the outer layers, enabling persistent bacterial infection. Microorganisms embedded in biofilms can catalyze chemical and biological reactions that cause metal corrosion in the pipelines and bulk tanks, besides interfering with the efficiency of heat transfer. The time necessary for biofilm formation depends on the frequency of equipment cleaning. Surfaces that are in contact with food products must be cleaned several times a day, and other surfaces in the food production environment, such as walls, may be cleaned at least only once a week. The surface of finished products may be contaminated by direct contact, and the food production environment may indirectly contaminate the finished products via vectors, ventilation and cleaning systems, and food handlers.