Grodeska Stephanie M, Jones Jessica L, Arias Covadonga R, Walton William C
1 Auburn University Shellfish Laboratory, School of Fisheries, Aquaculture & Aquatic Sciences, Auburn University, 150 Agassiz Street, Dauphin Island, Alabama 36528; and.
2 U.S. Food and Drug Administration, Division of Seafood Science and Technology, Gulf Coast Seafood Laboratory, Dauphin Island, Alabama 36528; and.
J Food Prot. 2017 Aug;80(8):1280-1287. doi: 10.4315/0362-028X.JFP-16-297.
The expansion of off-bottom aquaculture to the Gulf of Mexico has raised public health concerns for human health officials. High temperatures in the Gulf of Mexico are associated with high levels of Vibrio parahaemolyticus and Vibrio vulnificus. Routine desiccation practices associated with off-bottom aquaculture expose oysters to ambient air, allowing Vibrio spp. to proliferate in the closed oyster. Currently, there is limited research on the length of time needed for Vibrio spp. levels in desiccated oysters to return to background levels, defined as the levels found in oysters that remain continually submersed and not exposed to ambient air. This study determined the time needed to return V. parahaemolyticus, V. vulnificus, and Vibrio cholerae levels to background levels in oysters exposed to the following desiccation practices: 3-h freshwater dip followed by 24-h ambient air exposure, 27-h ambient air exposure, and control. All oysters were submerged at least 2 weeks prior to the beginning of each trial, with the control samples remaining submerged for the duration of each trial. Vibrio spp. levels were enumerated from samples collected on days 0, 1, 2, 3, 7, 10, and 14 after resubmersion using a three-tube most-probable-number enrichment followed by BAX PCR. V. cholerae levels were frequently (92%) below the limit of detection at all times, so they were not statistically analyzed. V. parahaemolyticus and V. vulnificus levels in the 27-h ambient air exposure and the 3-h freshwater dip followed by 24-h ambient air exposure samples were significantly elevated compared with background samples. In most cases, the Vibrio spp. levels in oysters in both desiccation treatments remained elevated compared with background levels until 2 or 3 days post-resubmersion. However, there was one trial in which the Vibrio spp. levels did not return to background levels until day 7. The results of this study provide scientific support that oyster farmers should be required to implement a minimum 7-day resubmersion regimen. This length of time allowed the Vibrio spp. levels to become not significantly different across all treatments.
海底养殖向墨西哥湾的扩张引起了人类健康官员对公共卫生的担忧。墨西哥湾的高温与副溶血性弧菌和创伤弧菌的高含量有关。与海底养殖相关的常规干燥做法使牡蛎暴露于环境空气中，从而使弧菌属在封闭的牡蛎中大量繁殖。目前，关于干燥牡蛎中弧菌属含量恢复到背景水平所需的时间（背景水平定义为持续浸没且未暴露于环境空气中的牡蛎中的含量）的研究有限。本研究确定了暴露于以下干燥做法的牡蛎中副溶血性弧菌、创伤弧菌和霍乱弧菌含量恢复到背景水平所需的时间：3小时淡水浸泡后24小时环境空气暴露、27小时环境空气暴露以及对照。在每次试验开始前，所有牡蛎至少浸没2周，对照样本在每次试验期间一直保持浸没状态。使用三管最可能数富集法随后进行BAX PCR，对重新浸没后第0、1、2、3、7、10和14天采集的样本进行弧菌属含量计数。霍乱弧菌含量在所有时间点经常（92%）低于检测限，因此未进行统计分析。与背景样本相比，27小时环境空气暴露样本以及3小时淡水浸泡后24小时环境空气暴露样本中的副溶血性弧菌和创伤弧菌含量显著升高。在大多数情况下，两种干燥处理的牡蛎中的弧菌属含量与背景水平相比，在重新浸没后2至3天一直保持升高。然而，有一次试验中弧菌属含量直到第7天才恢复到背景水平。本研究结果提供了科学依据，表明应要求牡蛎养殖户实施至少7天的重新浸没方案。这段时间使得所有处理的弧菌属含量没有显著差异。
