S. aureus is present on the skin and in the nasopharnyx area of humans and animals. Often, S. aureus will get into food from food handlers, from animal skin, or from dirty food preparation surfaces. S. aureus cannot grow at refrigeration temperatures and is a relatively poor competitor with other food microflora. S. aureus growth usually occurs during temperature abuse. Temperature abuse occurs when food is kept in the temperature danger zone - 4.4 to 60°C (40 to 140°F) - for prolonged periods of time. The optimal temperature for S. aureus growth is between 18 to 40°C (64 to 104°F). Because S. aureus grow poorly in the presence of other food microflora, these organisms tend to grow better in cooked or processed foods. In addition, S. aureus can grow at lower a w compared to most other bacteria (down to a w 0.85). Therefore, S. aureus may grow under a reduced a w or on high salt foods that will inhibit the growth of most pathogens as long as the temperature permits growth. Metabolically, S. aureus can utilize mannitol, which is not seen with other staphylococcal species, such as Staphylococcus epidermidis. The production of the enzyme coagulase by a majority of S. aureus strains can also be used to differentiate this species from other staphylococci.