目的:调查生面粉和生面粉制品可能受到的污染,如煎饼/面糊混合物,沙门氏菌,通用大肠杆菌和STEC。样品包括四个月(2020年1月至4月)在英国出售的面粉。面包和面粉的规定,1998年规定了面粉和面包中的允许成分,但没有规定定期监测面粉和面粉制品的微生物质量。
结果:由地方当局采样官员根据当前的微生物食品采样指南收集生面粉样品,然后将其运送到实验室进行检查。进行微生物测试以检测沙门氏菌。,一般大肠杆菌和产志贺毒素的大肠杆菌(STEC)的特征在于存在STEC毒力基因:stx1,stx2和亚型,EAE,ipah,aggR,lt,sth和stp,使用分子方法(PCR)。在采样的882种面粉中,沙门氏菌的发生率为0.1%(单个阳性样品包含多种成分,例如面粉,干鸡蛋和干牛奶,在英国碾磨),和68个样品(7.7%)含有>20CFU/g水平的普通大肠杆菌。面粉样品的分子表征显示10个样品(5个进口和5个来自英国)(1.1%)中存在志贺毒素(stx)基因,从7个样品(0.8%)中分离出STEC。对沙门氏菌和STEC分离株进行测序,以提供基因型的进一步表征,并与UKHSA档案中保存的人类临床分离株的序列进行比较。使用我们基于遗传相似性的解释标准,没有一个STEC面粉分离物与先前观察到的人类病例相关,虽然混合成分产品中的单一沙门氏菌血清型Newport分离株与2019年的人类病例相似,但来自英国,S.纽波特。尽管没有报道过与这些面粉样品中的分离株相匹配的STEC的人类病例,已知检测到的一些相同的血清型和stx亚型在其他情况下引起了疾病。
结论:结果表明,虽然发病率较低,面粉中可能存在沙门氏菌和STEC,并且证明了来自面粉产品的沙门氏菌分离株与人类沙门氏菌病之间的遗传联系。
OBJECTIVE: To investigate the possible contamination of raw flour and raw flour-based products, such as pancake/batter mixes, with Salmonella, generic Escherichia coli, and Shiga-toxin-producing E. coli (STEC). Samples included flours available for sale in the UK over a period of four months (January to April 2020). The Bread and Flour regulations, 1998 state the permitted ingredients in flour and bread but it does not specify the regular monitoring of the microbiological quality of flour and flour-based products.
RESULTS: Samples of raw flour were collected by local authority sampling officers in accordance with current guidance on microbiological food sampling then transported to the laboratory for examination. Microbiological testing was performed to detect Salmonella spp., generic E. coli, and STEC characterized for the presence of STEC virulence genes: stx1, stx2, and subtypes, eae, ipah, aggR, lt, sth, and stp, using molecular methods Polymerase Chain Reaction (PCR). Of the 882 flours sampled, the incidence of Salmonella was 0.1% (a single positive sample that contained multiple ingredients such as flour, dried egg, and dried milk, milled in the UK), and 68 samples (7.7%) contained generic E. coli at a level of >20 CFU/g. Molecular characterization of flour samples revealed the presence of the Shiga-toxin (stx) gene in 10 samples (5 imported and 5 from the UK) (1.1%), from which STEC was isolated from 7 samples (0.8%). Salmonella and STEC isolates were sequenced to provide further characterization of genotypes and to compare to sequences of human clinical isolates held in the UKHSA archive. Using our interpretive criteria based on genetic similarity, none of the STEC flour isolates correlated with previously observed human cases, while the singular Salmonella serotype Newport isolate from the mixed ingredient product was similar to a human case in 2019, from the UK, of S. Newport. Although there have been no reported human cases of STEC matching the isolates from these flour samples, some of the same serotypes and stx subtypes detected are known to have caused illness in other contexts.
CONCLUSIONS: Results indicate that while the incidence was low, there is a potential for the presence of Salmonella and STEC in flour, and a genetic link was demonstrated between a Salmonella isolate from a flour-based product and a human case of salmonellosis.