Faecal contamination of bivalve molluscan shellfish (BMS) can lead to infections from enteric pathogens if consumed. Across Europe, the faecal indicator bacteria Escherichia coli, is used to determine contamination of BMS harvesting areas. The reference most probable number (MPN) method for E. coli in BMS takes around 48 h from sample receipt to result. In this study, an alternative method was developed in which the final, E. coli confirmation step in the MPN method (usually carried out on chromogenic TBX agar) was replaced by presence/absence real-time PCR (qPCR). This qPCR-MPN method was directly compared with the reference TBX-MPN method using 194 BMS samples consisting of mussels (Mytilus spp.), Pacific oysters (Crassostrea gigas) and common cockles (Cerastoderma edule). The qPCR-MPN method correlated positively with the TBX-MPN method (Kendall's tau coefficient = 0.812). However, the strength of this correlation varied between BMS species, with mussels having the poorest correlation (0.677) followed by Pacific oysters (0.795) and common cockles (0.890). There were some samples for which the difference between the two methods was higher than might be expected by statistical probability alone. Variations in the way in which the two confirmation methods work may account for much of this variation. This method may serve as an ad hoc, rapid assessment method that is complementary to the official reference method and could be easily implemented in many official control laboratories.

如果食用双壳类软体动物贝类 (BMS) 的粪便污染，可导致肠道病原体感染。在整个欧洲，粪便指示菌大肠杆菌被用于确定 BMS 收获区的污染情况。BMS 中大肠杆菌的参考最可能数 (MPN) 方法从收到样品到获得结果大约需要 48 小时。在本研究中，开发了一种替代方法，其中MPN 方法中的最终大肠杆菌确认步骤（通常在显色 TBX 琼脂上进行）被存在/不存在实时 PCR (qPCR) 取代。该 qPCR-MPN 方法直接与参考 TBX-MPN 方法进行比较，使用 194 个 BMS 样品，包括贻贝（贻贝属）、太平洋牡蛎（Crassostrea gigas ) 和普通鸟蛤 ( Cerastoderma edule )。qPCR-MPN 方法与 TBX-MPN 方法呈正相关（Kendall tau 系数 = 0.812）。然而，这种相关性的强度在 BMS 物种之间有所不同，贻贝的相关性最差（0.677），其次是太平洋牡蛎（0.795）和普通蛤（0.890）。对于某些样本，两种方法之间的差异高于仅通过统计概率可能预期的差异。两种确认方法工作方式的差异可能是造成这种差异的主要原因。这种方法可以作为一种临时的、快速的评估方法，作为官方参考方法的补充，可以很容易地在许多官方控制实验室中实施。