Tran Mai-Lan, Delannoy Sabine, Fach Patrick
'Pathogenic E. coli' Unit (COLiPATH) and Genomics platform 'IdentyPath' (IDPA), Laboratory for Food Safety, Anses (The French Agency for Food, Environmental and Occupational Health & Safety), Maisons-Alfort, France.
Front Microbiol. 2025 Feb 12;16:1543686. doi: 10.3389/fmicb.2025.1543686. eCollection 2025.
Detection of Shiga toxin-producing (STEC) presenting high risk of human infections is challenging. In France, the latest Anses opinion categorized STEC in four groups based on their association with severe forms of clinical infection. STEC strains carrying the gene, particularly those of serogroups O157, O26, O111, O103, O145, O121, O45 and more recently O80 (top 8 serogroups), are usually monitored worldwide, whereas -negative STEC strains that are less clinically significant are not surveyed. Screening food enrichment broths with classical genetic markers (, ) can overestimate the presence of highly virulent STEC, causing needless disruption and costs for food producers. Recently the updated MLG5C reference method introduced additional genetic markers (, ) in the detection scheme to improve specificity and effectiveness of priority STEC detection in foodstuffs. This study, conducted on beef samples with a new method supporting the regulatory USDA-FSIS MLG5C.04 method, showed that 92% of the -positive samples carry alone or in association with . Among the -positive samples, and/or subtypes dominate. Introduction of , markers on 868 / beef enrichment broths reduced the number of presumptive positive results by 31%, compared to the ISO/TS 13136:2012 reference method. Subsequent analysis of the presumptive positives combining the O-group and the -subtype provided also a significant reduction of the number of the presumptive positive for the top 8 -positive STEC serogroups; and showed that O26, O103 and O157 were the most prevalent ones. Regarding the / samples, which are proportionally extremely predominant in beef as compared with the / samples, 65% of them were positive for the serogroups monitored in this study (O91, O171, O174, O148, O146, O128 O113 and O104). The high occurrence of serogroup O113 observed in beef samples is not corroborated by the clinical data reported in France. Routine testing of beef samples should be revised to prioritize a hierarchical surveillance system based only on high risk STEC (STEC carrying the gene) and not on all STEC. This approach would provide Food Business Operators a significant improvement, saving time and costs while maintaining a high level of product safety.
检测具有高人类感染风险的产志贺毒素大肠杆菌（STEC）具有挑战性。在法国，法国食品安全局（Anses）的最新意见根据STEC与严重临床感染形式的关联将其分为四类。携带stx基因的STEC菌株，特别是血清型O157、O26、O111、O103、O145、O121、O45以及最近的O80（前8个血清型）的菌株，通常在全球范围内受到监测，而临床意义较小的stx阴性STEC菌株则未被调查。用经典遗传标记（stx、eae）筛选食品增菌肉汤可能会高估高毒力STEC的存在，给食品生产商带来不必要的干扰和成本。最近更新的MLG5C参考方法在检测方案中引入了额外的遗传标记（rfbE、wzy），以提高食品中优先STEC检测的特异性和有效性。本研究采用一种支持美国农业部食品安全检验局（USDA-FSIS）MLG5C.04监管方法的新方法对牛肉样本进行检测，结果表明，92%的stx阳性样本单独携带或与eae一起携带stx。在stx阳性样本中，stx和/或eae亚型占主导地位。在868个stx/rfbE牛肉增菌肉汤中引入rfbE、wzy标记后，与ISO/TS 13136:2012参考方法相比，推定阳性结果数量减少了31%。随后对推定阳性结果结合O群和stx亚型进行分析，也显著减少了前8个stx阳性STEC血清型的推定阳性数量；结果显示，O26、O103和O157是最常见的血清型。关于stx/rfbE样本，与stx/rfbE样本相比，其在牛肉中所占比例极高，其中65%的样本对本研究监测的血清型（O91、O171、O174、O148、O146、O128、O113和O104）呈阳性。在牛肉样本中观察到的O113血清型的高发生率并未得到法国报告的临床数据的证实。应修订牛肉样本的常规检测，以优先建立一个仅基于高风险STEC（携带stx基因的STEC）而非所有STEC的分级监测系统。这种方法将为食品企业经营者带来显著改善，节省时间和成本，同时保持较高的产品安全水平。
