[Growth of Staphylococcus aureus in solid media with a water activity less than 0.86]

The purpose of this study was to determine whether S. aureus could grow in solid substrates with aw 0.843 adjusted by water adsorption. The media used included dehydrated powder of pork, beef and milk as basic substrates in order to compensate an eventual deficiency; additional source of nutrients was added. The tested strains were ATCC 6538 P, FDA-C243, NA1 and FM1. It was observed that no strain grew at 30 degrees C in those media at aw 0.843. These data were compared with others which indicate that S. aureus could grow al aw 0.83-0.84. The possible reasons for the difference in the minimal aw value reported to be required for the growth of S. aureus are discussed.