快速检测病原菌含量的简易微流控系统

针对现有水产养殖病原菌检测时效性差、自动化程度低的缺点,提出了一种快速检测水产养殖病原菌含量的简易微流控系统研究方法。该系统将微电极构造于微流控芯片通道底部并与数字阻抗测量电路连接,通过在磁珠表面包被水产病原菌抗体,利用外部高斯磁场控制诱导磁珠捕获水产病原菌,并将水产病原菌与磁珠结合体带至微电极阵列,通过在电极端构建基于阻抗测量的计数电路,从而有效检测水产病原菌含量。研究结果表明该系统能够有效测量水产病原菌的含量,检测时间由传统的平板计数法48 h减少至30 min,检测效率提高为原来的60多倍,检出限相比现有的微流控阻抗法缩小100倍。     

ASSESSING AND MANAGING THE RISKS OF PATHOGEN TRANSFER FROM LIVESTOCK MANURES INTO THE FOOD CHAIN

A review was undertaken of (a) the levels and prevalence of Salmonella spp., Campylobacter spp., Listeria monocytogenes, Escherichia coli 0157. Cryptosporidium parvum and Giardia intestinalis in livestock manure, and (b) factors which affect their survival during storage and following land application. Pathogens are commonly present in livestock manures and can survive in soil for several months or years after spreading or excretion onto land. Temperature was identified as being the most important factor influencing pathogen survival, although pH, UV light and drying were also important. Various practical measures to minimise the risk of pathogen transfer into the food chain were identified, including treatment, extended storage and no/harvest periods following land spreading. Guidelines are being developed on managing farm manures to minimise the risks of microbiological contamination of ready-to-eat crops.     

Prevalence and antimicrobial resistance of Campylobacter species isolated from the avian eggs

Campylobacter is one of the most important food borne pathogens that cause bacterial gastroenteritis worldwide. The most commonly isolated species in humans are Campylobacter jejuni (C. jejuni) and Campylobacter coli. The emergence of antimicrobial resistance in Campylobacter spp. has been a growing public health concern globally. Information about antimicrobial resistance of Campylobacter at different levels of production is important for the development of control strategies for this pathogen. This study was conducted to determine the prevalence and antimicrobial resistance of Campylobacter spp. isolated from different eggs from different avian species in Iran. A total of 440 egg samples were collected from different avian and analyzed for the presence of Campylobacter spp. in eggshell and eggs content under sterile conditions using Campylobacter selective agar base and the species were identified by biochemical tests. The suspected colonies were subjected to PCR assay for final confirmation as Campylobacter spp., and identification of C. jejuni or Campylobacter coli. Antimicrobial susceptibility testing was performed by the Kirby–Bauer disk diffusion method using Mueller Hinton agar. Campylobacters were detected in a total of 7 out of 100 (7%) eggshell of chicken samples and in 3 out of 60 (5%) eggshell of duck samples. In addition, Campylobacter spp. were also detected in 3.3%, 2.5%, 4.2%, 5% and 3.8 of the eggshell of goose, ostrich, partridge, quail and turkey samples, respectively. The overall prevalence rate of Campylobacter species from different avian eggs was found to be 7.7% (34/440). Among different avian egg samples, Campylobacter jejuni was more frequently isolated 28 (n = 28, 6.3%) than C. coli 6 (n = 6, 1.3%). In addition, the prevalence of C. jejuni was highest in summer and lowest in autumn. In this study Campylobacter spp. showed significant difference in resistance pattern with tetracycline and ciprofloxacin but gentamicin resistance was not found in both C. coli and C. jejuni isolates. Therefore, gentamicin is safe and effective drugs for the treatment of human campylobacteriosis if avian egg is considered as the source of infection.     

Behaviour of food-borne pathogens on dry cured sausage manufactured with herbs and spices essential oils and their sensorial acceptability

Dry cured sausages such as Portuguese chouriço de vinho are made generally with roughly minced pork and fat and seasoned with a large variety of herbs and spices. It is a particular sausage because meat is marinated in wine with other seasonings during 24–48 h before stuffing. Nowadays, health concerns of consumers have left food processors with less flexibility to choose preservative substances and methods. Thus, the objective of this study was to assess the antimicrobial effect of essential oils (EOs) of herbs and spices traditionally used in seasoning dry cured sausage chouriço against Salmonella spp., Listeria monocytogenes and Staphylococcus aureus. First, antibacterial activity of 14 EOs was screened by disk diffusion assay. Those EOs that displayed antimicrobial activity were further characterized by GC–MS and added as natural antimicrobial substances to the manufacture of chouriço at two concentrations (0.005% and 0.05%). Samples were analyzed 24 h after the preparation of the batter and after 3, 8, 15 and 21 days.After 15 days of drying, Salmonella spp. and L. monocytogenes counts decreased by ca. 2 log cfu/g in all samples. At 3 days, Salmonella spp. was already undetectable in chouriço made with 0.05% of garlic and oregano EOs. Both Salmonella spp. and L. monocytogenes were not detected after 8 and 15 days of drying respectively. S. aureus was still presented after 21 days of drying although its counts were not high enough to a potential enterotoxins presence. Utilization of EOs in manufacture of dry cured sausage resulted in an interesting strategy to improve its safety against Salmonella spp, L. monocytogenes and S. aureus, but with sensory limitations, that does not allow its use in high concentrations, that are those more interesting for pathogen inhibition.However, results with good potential to be applied by the industry were found, once the level of addition of 0.005% contributed for significant reductions on the pathogen's counts and for a shorter period to achieve the not detectable level, allowing the industry to shorten the drying period and, thereafter increasing yield production.     

低聚糖拮抗食源性致病菌的研究及应用进展

食源性致病菌导致的食品安全问题已成为世界上重要的公共卫生问题之一,寻找高效且安全的天然抑菌剂引起人们的关注。目前有研究表明低聚糖类物质如果胶低聚糖、低聚壳聚糖、褐藻胶低聚糖等具有较好的抑菌效果,并且低聚糖大多来源于植物胶、甲壳动物,天然海藻多糖等自然物质,对环境污染较小;因此低聚糖能够作为潜在的天然抑菌剂被广泛应用在食品行业中,具有一定的研究意义和应用前景,已经逐渐成为食品行业新的研究热点。该研究综述了几种低聚糖对食源性致病菌的抑菌作用,并分析总结了其抑菌机制：一是低聚糖破坏细菌细胞壁和细胞膜,二是渗入细胞内部破坏蛋白质和核酸物质;同时展望了低聚糖在涂膜保鲜和作为食品添加剂两方面的应用,以期为进一步深入研究低聚糖的作用和在食品行业的应用提供理论参考。     

2015—2018年上海市浦东新区食源性疾病主动监测病原学及流行病学特征分析

目的 了解上海市浦东新区特定病原体食源性疾病的流行趋势和特征,为制定食源性疾病防控策略提供参考。方法 采集2015—2018年于上海市浦东新区开展食源性疾病主动监测的数据,2家哨点医院采集以腹泻症状为主诉感染病例的粪便或肛拭子标本,进行副溶血性弧菌、沙门菌、志贺菌、致泻大肠埃希菌、空肠弯曲菌和诺如病毒检验,同时对患者进行相关信息采集、分析。结果 共监测和采集2 871例腹泻病例的粪便或肛拭子标本,病原体总体检出率为23.55%(676/2 871),其中,诺如病毒为20.04%(97/484)、致泻大肠埃希菌为11.84%(340/2 871)、空肠弯曲菌为7.21%(68/943)、副溶血性弧菌为4.01%(115/2 871)、沙门菌为3.27%(94/2 871)、志贺菌为0.28%(8/2 871);第三季度的病原体检出率较高,呈现较明显的夏秋季高峰;可疑食物主要是混合/多种食品(41.12%,278/676),其次为水产动物及其制品(22.19%,150/676)和肉与肉制品(10.95%,74/676)。结论 诺如病毒和致泻大肠埃希菌是上海市浦东新区腹泻病例的主要病原体,应进一步完善食源性疾病主动监测,对特定病原体阳性病例开展流行病学个案调查,为开展有效防控提供技术支持。     

软腐猕猴桃果实真菌类病原菌的生物多样性分析

本文对湖南地区主要猕猴桃产区猕猴桃软腐果实真菌类病害的多样性分布规律进行系统分析,为猕猴桃软腐病原真菌多样性的深入研究提供基础数据和理论依据。采用IlluminaHi Seq高通量测序技术对5处软腐猕猴桃(A、B、C、D、E),15组果实样品中微生物ITS扩增子二代测序数据采集,进行生物信息学分析。5处软腐猕猴桃果实中真菌种类较为丰富,真菌丰富度指数和多样性指数较高,尤其是A、B、C处,相对于D、E处存在极显著差异(p<0.01)。在不同猕猴桃果实中得到了2个门的优势微生物。子囊菌门(Ascomycota)为最优势菌门,主要分布在D和E处,群类相对丰度为19.20%,且远远大于次优势菌门-担子菌门(Basidiomycota,6.80%,主要分布在A、B、C处),表现出非常明显的优势;间座壳属Diaporthe相对丰度最高,达到了14.00%,相对于其它属病原菌均具有极显著性差异(p<0.01),此菌在D、E组含量相对较高,在本组内达到了30%以上,其余3组几乎没有。布勒弹孢酵母属Bullera相对丰度为4.90%,此菌为各组共有的优势菌属,A、B、C组略高,在本组内达到了5.50%左右,D、E组则为3.50%左右。葡萄座腔菌属Neofusicoccum相对丰度为3.20%,此菌在E组含量相对较高,在本组内达到了15.00%以上,其余4组几乎没有。红菇属Russula相对丰度为0.60%,及其它较少的担子菌门菌属Tomentella、Phialocephala、oidiodendron、cenococcum等,此外,具有软腐猕猴桃果实潜力的菌属有茎点酶菌属(homa)、青霉属(penicillium)及拟青霉属(simplicillium)等。实验为猕猴桃软腐病的防治提供了一定理论基础,今后对猕猴桃果实软腐病防治时可针对性的杀灭间座壳属和葡萄座腔菌属微生物,以提高果实的耐贮性。     

乳品中食源性致病菌快速检测技术研究进展

近年来食源性疾病事件频发,食源性疾病已成为全球化的公共卫生问题,其中有害微生物污染占了较大比重,而乳品因营养丰富可以为众多微生物提供生长所需的营养物质易被其污染。传统的微生物检测方法虽然设备简单、成本低廉,但普遍检测周期长、操作繁琐,对人员操作水平和检验经验要求高。本文综述了分子生物学技术、免疫学技术、光谱技术、基质辅助激光解吸电离飞行时间质谱技术、生物传感器技术以及流式细胞技术在乳品食源性致病菌快速检测的研究进展,展望了乳品中食源性致病菌检测技术向在线化、便捷化、高效化发展前景,以期为后续研究提供参考和借鉴。     

9274份肉及肉制品食源性致病菌监测结果分析

目的 了解吉林省9274份肉及肉制品食源性致病菌污染情况,为防控食源性疾病提供科学依据。方法从吉林省9个地市级行政区采集市售6类肉及肉制品样品共9274份,包括生畜肉、生禽肉、熟肉制品、调理肉制品、冷冻肉糜制品和动物血液及制品。按照国家标准方法检测10种食源性致病菌。结果 全部9274份样本食源性致病菌总阳性检出率为3.9%(366/9274)。检出率最高为调理肉制品 (13.0%,63/483),其次是生禽肉(5.6%,107/1900)和生畜肉(5.0%,71/1428)。检出的主要致病菌为单核细胞增生李斯特菌、金黄色葡萄球菌和沙门菌。生禽肉中弯曲菌检出率(7.5%,31/411)和产气荚膜梭菌检出率(3.9%,7/180)均高于沙门菌检出率(3.5%,8/231)。生禽肉、生畜肉中未检出小肠结肠炎耶尔森菌。动物血液及制品未检出单细胞增生李斯特菌、弯曲菌和小肠结肠炎耶尔森菌。冷冻肉糜制品未检出沙门菌。熟肉制品未检出大肠埃希氏菌O157、志贺菌和蜡样芽胞杆菌。熟肉制品各年度检出率范围为1.3%-4.4%。结论 吉林省市售的肉及肉制品较长时间受到不同程度的食源性致病菌污染,存在食源性疾病发生的风险。