Halpin-Dohnalek Margaret I, Marth Elmer H
Department of Food Science and The Food Research Institute, University of Wisconsin-Madison, Madison, Wisconsin 53706.
J Food Prot. 1989 Aug;52(8):540-543. doi: 10.4315/0362-028X-52.8.540.
Staphylococcus aureus strains 100-A, 196-E, 254, 473, 505, and 521 generally grew better in skim milk and whole milk (3.5% milk fat) than in light cream (18% milk fat) and heavy whipping cream (36% milk fat) at 25 and 37°C. S. aureus strains grew to greater than 10/ml from an inoculum of ca. 10/ml in skim and whole milk held at 37°C. From the same level of inoculum, strains grew to 10-10/ml in light cream held at 37°C. A 10 to 100-fold increase in population was observed for most strains in heavy whipping cream inoculated with ca. 10 S. aureus /ml and held at 37°C. Less than a 10-fold increase in population was noted for strain 254 in heavy whipping cream held at 37°C. When strains of S. aureus were inoculated into milks and creams and held at 25°C, populations of the pathogen increased approximately 100-fold in skim and whole milk and 10-fold or less in light cream and heavy whipping cream. S. aureus was enumerated using Chapman Stone, Mannitol Salt, Baird-Parker, and Vogel-Johnson agars; best results were obtained with Baird-Parker and Vogel-Johnson agars, particularly when high-fat fluid products were tested. Milk fat content, incubation temperature, and strain variation influenced the ability of S. aureus to grow in various dairy fluids.
金黄色葡萄球菌菌株100 - A、196 - E、254、473、505和521在25℃和37℃下，通常在脱脂牛奶和全脂牛奶（含3.5%乳脂）中比在淡奶油（含18%乳脂）和重搅打奶油（含36%乳脂）中生长得更好。金黄色葡萄球菌菌株在37℃下保藏的脱脂牛奶和全脂牛奶中，从约10/ml的接种量生长至超过10/ml。从相同接种水平开始，菌株在37℃下保藏的淡奶油中生长至10⁴ - 10⁵/ml。对于接种约10个金黄色葡萄球菌/ml并在37℃下保藏的重搅打奶油中的大多数菌株，观察到菌数增加了10至100倍。在37℃下保藏的重搅打奶油中，菌株254的菌数增加不到10倍。当金黄色葡萄球菌菌株接种到牛奶和奶油中并在25℃下保藏时，该病原体的菌数在脱脂牛奶和全脂牛奶中增加约100倍，在淡奶油和重搅打奶油中增加10倍或更少。使用查普曼·斯通琼脂、甘露醇盐琼脂、贝尔德 - 帕克琼脂和沃格尔 - 约翰逊琼脂对金黄色葡萄球菌进行计数；使用贝尔德 - 帕克琼脂和沃格尔 - 约翰逊琼脂可获得最佳结果，尤其是在检测高脂肪流体产品时。乳脂含量、培养温度和菌株差异影响金黄色葡萄球菌在各种乳制品流体中的生长能力。
