Hammack T S, Feng P, Amaguaña R M, June G A, Sherrod P S, Andrews W H
U.S. Food and Drug Administration, Division of Microbiological Studies, Washington, DC 20204, USA.
J AOAC Int. 1997 Mar-Apr;80(2):335-40.
The relative efficacies of hemorrhagic coli (HC) agar and several formulations of sorbitol MacConkey (SorMac) agar, with and without 0.1% (w/v) 4-methyllumbelliferyl-beta-D-glucuronide (MUG), in recovering unstressed and heat-stressed Escherichia coli O157:H7 from Brie cheese, ice cream, and whole milk were determined. Recovery of unstressed E. coli O157:H7 was determined quantitatively by spread-plating diluted samples onto different agars and performing plate counts. Recovery of stressed E. coli O157:H7 was determined qualitatively by enriching samples in modified trypticase soy broth, streaking the incubated enrichments, and isolating E. coli O157:H7 colonies from the agars. HC agar and the SorMac agar formulations did not differ significantly in their ability to recover unstressed E. coli O157:H7 from ice cream and whole milk; however, HC agar recovered significantly more unstressed E. coli O157:H7 from Brie cheese than did the SorMac agar formulations. Bacteriological Analytical Manual and Oxoid SorMac agar formulations made from individual ingredients, did not differ significantly in recovering unstressed E. coli O157:H7 from Brie cheese. The efficiency of the commercially available Oxoid SorMac agar could not be determined because of overgrowth by indigenous microflora. HC and SorMac agars did not differ significantly in recovering stressed E. coli O157:H7 from Brie cheese, ice cream, and whole milk. MUG had no apparent effect on recovery of either stressed or unstressed E. coli O157:H7 from the dairy foods examined.
测定了出血性大肠杆菌（HC）琼脂以及几种含有和不含0.1%（w/v）4-甲基伞形酮基-β-D-葡萄糖醛酸苷（MUG）的山梨醇麦康凯（SorMac）琼脂配方，从布里干酪、冰淇淋和全脂牛奶中回收未受胁迫和热胁迫的大肠杆菌O157:H7的相对效力。通过将稀释后的样品涂布在不同琼脂上并进行平板计数，定量测定未受胁迫的大肠杆菌O157:H7的回收率。通过在改良胰蛋白酶大豆肉汤中富集样品、对培养后的富集物进行划线接种以及从琼脂中分离大肠杆菌O157:H7菌落，定性测定受胁迫的大肠杆菌O157:H7的回收率。HC琼脂和SorMac琼脂配方从冰淇淋和全脂牛奶中回收未受胁迫的大肠杆菌O157:H7的能力没有显著差异；然而，HC琼脂从布里干酪中回收的未受胁迫的大肠杆菌O157:H7比SorMac琼脂配方显著更多。由单独成分制成的《细菌学分析手册》和Oxoid SorMac琼脂配方，从布里干酪中回收未受胁迫的大肠杆菌O157:H7时没有显著差异。由于本地微生物过度生长，无法确定市售Oxoid SorMac琼脂的效率。HC琼脂和SorMac琼脂从布里干酪、冰淇淋和全脂牛奶中回收受胁迫的大肠杆菌O157:H7时没有显著差异。MUG对所检测的乳制品中受胁迫或未受胁迫的大肠杆菌O157:H7的回收率没有明显影响。
