Division of Microbiology, National Institute of Health Sciences, 3-25-26, Tonomachi, Kawasaki-ku, Kawasaki, Kanagawa 210-9501, Japan.
Miyagi Prefectural Institute of Public Health and Environment, 4-7-2, Saiwai-cho, Miyagino-ku, Sendai 983-0836, Japan.
J Food Prot. 2022 Jan 1;85(1):173-179. doi: 10.4315/JFP-21-222.
Escherichia albertii is an emerging foodborne pathogen. Owing to its distribution in river water, it is important to determine the presence of E. albertii in aquaculture-related foods. In this study, we investigated the distribution of E. albertii in retail oyster samples. A total of 427 raw oyster samples (385 Pacific oysters and 42 Japanese rock oysters) were enriched in modified Escherichia coli broth (mEC) or mEC supplemented with novobiocin (NmEC) at 42°C. The cultures were used for E. albertii-specific nested PCR assay, as well as for E. albertii isolation using deoxycholate hydrogen sulfide lactose agar (DHL), DHL supplemented with rhamnose and xylose, and MacConkey agar supplemented with rhamnose and xylose. The population of E. albertii in nested PCR-positive samples was determined using the most-probable-number (MPN) method. E. albertii isolates were subjected to biochemical and genetic characterization. E. albertii was detected in 5 (1.6%) of 315 Pacific oyster samples (one piece each), 2 (2.9%) of 70 Pacific oyster samples (25 g each), and 2 (4.8%) of 42 Japanese rock oyster samples procured from four geographically distinct regions. A total of 64 E. albertii strains were isolated from eight of the nine nested PCR assay-positive oyster samples, and the MPN value was under the detection limit (<3 MPN/10 g). A specific season or month for detecting E. albertii was not observed in this study, suggesting that the pathogen is present in seawater. All the E. albertii isolates, except one, were positive for the virulence factor eae, indicating that these isolates have the potential to infect humans.
大肠杆菌 albertii 是一种新兴的食源性致病菌。由于其分布在河水中，因此确定水产养殖相关食品中是否存在大肠杆菌 albertii 非常重要。在本研究中，我们调查了零售牡蛎样本中大肠杆菌 albertii 的分布情况。总共采集了 427 份原始牡蛎样本（385 份太平洋牡蛎和 42 份日本石蚝），在 42°C 下分别用改良大肠埃希氏菌肉汤（mEC）或 mEC 中添加新生霉素（NmEC）进行富集。培养物用于大肠杆菌 albertii 特异性巢式 PCR 检测，以及使用脱氧胆酸钠氢硫化乳糖琼脂（DHL）、DHL 中添加鼠李糖和木糖以及 MacConkey 琼脂中添加鼠李糖和木糖进行大肠杆菌 albertii 分离。通过最可能数（MPN）法确定巢式 PCR 阳性样品中大肠杆菌 albertii 的数量。对大肠杆菌 albertii 分离株进行生化和遗传特征分析。在 315 份太平洋牡蛎样本（每份 1 个）、2 份（每份 25 克）太平洋牡蛎样本和 42 份日本石蚝样本（从四个不同地理区域采集）中检测到 5（1.6%）、2（2.9%）和 2（4.8%）份样本中存在大肠杆菌 albertii。从 9 个巢式 PCR 检测阳性牡蛎样本中的 8 个样本中分离出了总共 64 株大肠杆菌 albertii 菌株，且 MPN 值低于检测限（<3 MPN/10 g）。本研究未观察到特定季节或月份检测到大肠杆菌 albertii 的情况，表明该病原体存在于海水中。除了一株外，所有大肠杆菌 albertii 分离株均为毒力因子 eae 阳性，表明这些分离株具有感染人类的潜力。
