Park Sungsu, Durst Richard A
Department of Food Science and Technology, Cornell University, Geneva, New York 14456-0462, USA.
J Food Prot. 2004 Aug;67(8):1568-73. doi: 10.4315/0362-028x-67.8.1568.
Detection of Escherichia coli O157:H7 in fruit juices such as apple cider is necessary for diagnosis of infection and epidemiological investigations. However, inhibitors in the apple cider, such as endogenous polyphenols and acids, often decrease the sensitivity of PCR assays and immunoassays, thus routinely requiring laborious cell separation steps to increase the sensitivity. In the current study, polyethylene glycol (PEG)-derivatized liposomes encapsulating sulforhodamine B were tagged with anti-E. coli O157:H7 antibodies and used in an immunoliposome sandwich assay for the detection of E. coli O157:H7 in apple cider. Even without prior separation, this assay can detect E. coli O157:H7 in apple cider samples inoculated with as few as 1 CFU/ml after an 8-h enrichment period. The lower limit of detection in pure cultures without enrichment was 7 x 10(3) CFU/ml (280 CFU/40-microl sample). PEGylated immunoliposomes are suitable as an analytical reagent for the detection of E. coli O157:H7 in fruit juices containing polyphenols.
检测苹果汁等果汁中的大肠杆菌O157:H7对于感染诊断和流行病学调查很有必要。然而，苹果汁中的抑制剂，如内源性多酚和酸，常常会降低聚合酶链反应（PCR）检测和免疫检测的灵敏度，因此常规情况下需要费力的细胞分离步骤来提高灵敏度。在本研究中，包裹有磺基罗丹明B的聚乙二醇（PEG）衍生脂质体用抗大肠杆菌O157:H7抗体进行标记，并用于免疫脂质体夹心检测，以检测苹果汁中的大肠杆菌O157:H7。即使不进行预先分离，该检测方法在8小时富集期后，也能够检测出接种量低至1 CFU/ml的苹果汁样品中的大肠杆菌O157:H7。在未富集的纯培养物中，检测下限为7×10³ CFU/ml（280 CFU/40微升样品）。聚乙二醇化免疫脂质体适合作为一种分析试剂，用于检测含有多酚的果汁中的大肠杆菌O157:H7。
