昆明市首起由疑似肉毒梭菌引起食物中毒的实验室快速检测

目的快速查明昆明市一起疑似由肉毒梭菌引起食物中毒事件的病原菌的具体类别。方法根据GB4789.12-2016《食品安全国家标准食品微生物学检验肉毒梭菌及肉毒毒素检验》,样品在庖肉培养基中35℃厌氧增菌5 d后镜检,用2个不同生产厂家的肉毒梭菌实时荧光定量PCR(Real-time PCR)检测试剂进行检测并进行肉毒毒素分型。结果镜检符合典型的肉毒梭菌的特征,2个不同生产厂家的肉毒梭菌Real-time PCR检测结果均为阳性,且均检测出E型肉毒毒素。Real-time PCR检测只需在增菌后4～6 h的检测时间,即可得到结果,且无需进行菌体的纯化培养,鉴定时间节约至少96 h。结论此次事件为食用被E型肉毒梭菌及其毒素污染食品而引起的细菌性食物中毒事件,用Real-time PCR检测方法可对肉毒梭菌食物中毒事件作出快速判定。     

四川省肉毒梭菌PCR基因分型方法比较研究

目的比较分析4种肉毒毒素(botulinum neurotoxins,Bo NT)基因分型方法,为四川省监测和食物中毒中肉毒梭菌(Clostridium botulinum)分型鉴定提供可靠的方法。方法使用本实验室保存的6株肉毒梭菌(包括A、B、E型)验证4种肉毒梭菌PCR基因分型鉴定方法——美国食品药品监督管理局(FDA)多重PCR分型方法、国际标准化组织(ISO)的两种多重PCR分型方法和一种实时荧光PCR分型方法,比较方法间的差异,并初步分析差异原因。结果 3种多重PCR方法均可在一个反应中同时检测A、B、E 3种型别肉毒梭菌。ISO多重PCR方法 1中A型检测虽能获得预期条带,但结果条带不清晰。其余两种多重PCR方法在分型检测肉毒梭菌时,可获得清晰的预期条带。实时荧光PCR分型方法能在多重反应体系中同时检测到不同型的肉毒梭菌,但由于荧光标记相同,要获得分型结果需要分别检测各毒素型别。结论美国FDA多重PCR方法和ISO多重PCR方法 2操作较简单易行,可在四川省肉毒梭菌监测中推荐使用。     

石家庄市肉毒梭菌在环境中的分布研究

目的:了解石家庄市肉毒梭菌在环境中的分布情况,为预防、诊断、治疗肉毒梭菌食物中毒提供科学依据.方法:按照地貌,均匀抽取8个县(市、区),采集土壤、食品和水3类样品,检测肉毒梭菌污染情况.结果:采集土壤、水、食品3类样品共350份,肉毒梭菌检出15份,检出率为4.3%,其中,12份为8型肉毒毒素,3份为A型肉毒毒素.发生过肉毒中毒的县(市、区)肉毒梭菌检出率高于未发生过的县(市、区)(P<0.05).山区与平原肉毒梭菌检出率差异无统计学意义.结论:石家庄市外环境中肉毒梭菌污染较以前严重,并且存在A型肉毒毒素.     

我国首例由丁酸梭菌引起婴儿E型肉毒中毒实验室诊断研究

目的对一起疑似婴儿肉毒中毒进行实验室诊断研究。方法对1例疑似婴儿肉毒中毒病例的粪便、食用过的食品和生活环境涂抹共计30份标本/样品进行梭菌分离鉴定及肉毒毒素检测,对分离菌株进行产毒试验。结果将患儿粪便标本培养物上清液腹腔注射小鼠后可致小鼠出现典型肉毒毒素中毒表现(竖毛、呼吸困难并出现典型的蜂腰、四肢麻痹),继而死亡,且培养物上清液经胰酶处理后毒性增强,表现为小鼠出现中毒及死亡时间较未处理组明显缩短。但培养物上清液经100℃加热处理后再次染毒动物,小鼠未出现中毒和死亡。混合型肉毒毒素诊断血清及单价抗E型肉毒毒素诊断血清可对小鼠起到保护作用。从患儿的粪便标本中分离到G~+芽胞杆菌,该菌在哥伦比亚血平板上呈不规则半透明扁平菌落,边缘根状生长,并携带E型肉毒毒素产毒基因,16S rRNA将其鉴定为丁酸梭菌,产毒试验结果显示该菌株可产E型肉毒毒素。结论该起婴儿中毒事件是由感染产E型肉毒毒素的丁酸梭菌引起。     

某企业婴儿肉毒中毒乳粉相关样品中肉毒梭菌的分离与分型

目的 对从某企业获取的30批次婴儿配方乳粉样品进行肉毒毒素和肉毒梭菌检测，对分离到的1株B型肉毒梭菌进行全基因组测序分析。方法 参照GB 4789.12—2016《食品安全国家标准 食品微生物学检验 肉毒梭菌及肉毒毒素检验》对样品进行肉毒梭菌分离及肉毒毒素分型实验；对分离到的菌株进行全基因组测序，并分析菌株的遗传特征。结果 30批次样品中均未检出肉毒毒素；将增菌液进行小鼠腹腔注射后，4批次乳粉样品出现了典型小鼠肉毒中毒症状，但仅从1批次乳粉样品中分离到肉毒梭菌。基因组测序分析显示，该菌为Ⅰ群B型肉毒梭菌，毒素基因簇为Ha型，毒素基因为B2亚型。结论 针对背景微生物复杂的婴儿配方乳粉中肉毒梭菌检测，不应以菌种分离作为金标准，而应以增菌液小鼠毒性实验结合肉毒抗血清保护实验作为确认方法。全基因组测序可对分离菌种进行精准鉴定和相关遗传特征分析，为中毒事件处理提供可靠的技术支撑。     

B型婴儿肉毒中毒的实验室诊断

目的对1例疑似肉毒毒素中毒的婴儿病例灌肠液样品进行实验室检测并确证。方法对患儿的灌肠液样品进行肉毒梭状芽胞杆菌分离及肉毒毒素检测。结果患儿灌肠液样品TPGY培养物腹腔注射小鼠后可致小鼠出现类似肉毒毒素中毒表现(竖毛、呼吸困难并出现典型的蜂腰、四肢麻痹)继而死亡。培养物经胰酶处理后小鼠仍出现中毒并死亡,但培养物经100℃加热处理后再次染毒动物,小鼠不出现中毒和死亡。A、B、C、D、E、F六种混合型肉毒毒素诊断血清及B型单价肉毒毒素诊断血清可对小鼠起到保护作用。患儿灌肠液样品中分离到梭状芽胞杆菌,该菌经表型、生化、PCR肉毒毒素产毒基因鉴定,结果为产B型肉毒毒素的肉毒梭状芽胞杆菌。结论患儿疾病与B型肉毒毒素中毒相关。     

食品中A型肉毒梭菌PCR-DHPLC检测方法的建立

目的:建立食品中A型肉毒梭菌的快速检测方法。方法:应用PCR结合变性高效液相色谱(DHPLC)技术,以A型肉毒梭菌的A型肉毒神经毒素基因作为靶基因设计特异性引物,PCR扩增的产物经DHPLC技术进行快速检测。以非A型肉毒梭菌,产气荚膜梭菌等23株参考菌株做特异性实验;A型肉毒梭菌DNA稀释成不同梯度,做灵敏度实验。结果:与传统的检测方法相比,该方法具有很好的特异性,方法灵敏度较高,最低检出限可达到为111ng/tube。结论:该方法可以快速、准确检测A型肉毒梭菌,是食品中致病菌快速检测的新技术。     

一起肉毒梭菌污染家庭腌制酸肉引起的食物中毒调查处置

目的查找病因,指导临床救治,以便为肉毒梭菌食物中毒事件制定防治措施提供依据。方法应用WS/T 83—1996《肉毒梭菌食物中毒诊断标准及处理原则》,通过现场流行病学调查、实验室检测和启动国家卫计委特效药系统紧急采购肉毒梭菌诊治血清应用于病人,分析致病原因与病程变化关系,确定诊治措施。结果确诊发病病人2例,仅1人住院。在住院患者血清中检出A、B型肉毒梭菌毒素,应用A、B型肉毒梭菌抗毒血清并对症治疗、机械通气,治疗25 d后,症状缓解,逐渐好转并康复出院。结论本次事件是由于进食被A、B型肉毒梭菌毒素污染的自家腌制酸肉导致的食物中毒事件。建议做好饮食安全宣传,加强食物中毒防控。     

肉毒梭菌的控制

肉毒梭菌分布广泛,其芽胞热抵抗力很强,其分泌的肉毒毒素致死力极强。目前对肉毒梭菌的检测与控制存在风险。     

新疆豆制品生产环境中肉毒梭菌的分离鉴定

从新疆伊犁察布查尔县的土壤中分离到1株优势菌,该分离株生长特性与A型肉毒梭菌(Clostridiumbotulinum type A)一致,为革兰氏阳性粗大杆菌,在EYA培养基上菌落边缘呈锯齿状,表面粗糙不规则,有较大的乳浊环。根据分离株的形态、生理生化特性,结合琼脂糖凝胶凝胶电泳图像、16SrDNA V6-V8序列(GenBank登录号:JN248616)与系统发育树分析,将其鉴定为A型肉毒梭菌。     

Contamination with storage fungi of human food from Cameroon

In a mycological study, a total of 95 human food samples were investigated to evaluate the incidence of fungal contamination in Cameroon by conventional identification method and partly confirmed by DNA sequencing. The isolated fungal spp. were further studied to determine their toxigenic potentials. The investigation revealed the predominance of Aspergillus and Penicillium with 96% of samples contaminated with at least one species of these fungi, whereas the incidence of co-contamination of samples was 85%. Aspergillus flavus and Aspergillus parasiticus (Flavi section) were the most predominant species contaminating mainly maize and peanuts. In addition, P. crustosum and P. polonicum were the most common contaminants belonging to the genus Penicillium. On the other hand, A. ochraceus (Circumdati section) registered a low incidence rate of 5%, including other members of the Aspergillus group. Other members of the genera Rhizopus and Alternaria spp. were also registered in the study. A majority of fungal strains of A. ochraceus, A. parasiticus, P. crustosum and P. polonicum isolated were toxigenic, producing the mycotoxins tested for, while none was detected in cultures of A. fumigatus. The high incidence rate of fungi contamination coupled with their potentials in producing mycotoxins gives a strong indication that the samples tested may likely be contaminated with various mycotoxins. There is need for further study to assess the incidence of mycotoxins contamination in similar food samples.     

Effect of growing bacteria isolated from food on staphylococcal growth and thermonuclease activity

The effect of growing Bacillus subtilis, Streptococcus faecalis var. liquefaciens, Escherichia coli and Lactobacillus plantarum on staphylococcal growth and thermonuclease (TNase) activity was investigated in liquid media and in foods. Growth of S. aureus at 37°C for 24 h under aerobic conditions was not inhibited by the four test strains. However, staphylococcal TNase activity decreased by 70 and 80% in the presence of B. subtilis and S. faecalis var. liquefaciens respectively. Staphylococcal growth and TNase activity were strongly inhibited by L. plantarum under anaerobic conditions at pH 5.5 but not at pH 7.0. Furthermore, optimal TNase production by S. aureus occurred in cooked meat medium containing 0.5 to 5.0% NaCl. TNase production significantly decreased at higher concentrations of NaCl. In the presence of B. subtilis and S. faecalis var. liquefaciens. TNase activity decreased at NaCl levels of 0.5 to 5.0% but not at NaCl concentrations>5.0%. TNase activity was also inhibited by growing B. subtilis and S. faecalis var. Liquefaciens at pH 5.0 to 7.0. The rate of inhibition increased with increasing pH. TNase activity was not inhibited after 48 h incubation at 20° in the presence of B. subtilis and S. faecalis var. liquefaciens but significant inactivation could be demonstrated at 25° to 37°C. The results obtained with artificially contaminated, sterile food samples were similar to those obtained with brain-heart infusion broth, but the degree of decrease in TNase activity in food was much lower than that in brain-heart infusion broth.     

Production of a red–purple food colorant from Opuntia stricta fruits by spray drying and its application in food model systems

Opuntia stricta fruit juice is a potential source of betacyanin pigments which can be used as a natural red-purple food colorant. In this work a powder food colorant was obtained by co-current spray drying of O. stricta fruit juices with a bench-scale two fluid nozzle spray dryer. Glucose syrup (DE 29) was used as drying aid. Optimum conditions for spray drying were as follow: juice content (20% v/v; 1.2 °Brix), glucose syrup content (10% w/v), liquid feed rate (0.72 l/h), spray air flow-rate (0.47 m³/h), drying air flow-rate (36 m³/h), and inlet drying air temperature 160 °C. Color was retained during the drying process (>98%) and drying yield was high (58%). The powder colorant showed high color strength (4.0), being this color strength stable when stored at room temperature for one month. This colorant was successfully applied in two food model systems: a yogurt and a soft-drink. Food presented a vivid red-purple tonality very attractive for consumers that was maintained after one month under refrigeration (4 °C) (ΔE < 5).     

刺五加在中国保健食品中的应用

文章主要阐述了刺五加在中国保健食品中的使用依据、应用现状，综述其保健功能相关的研究进展，并对其未来的发展方向进行了展望。     

Enantioseparation of catechin and epicatechin in plant food by chiral capillary electrophoresis

The enantiomers of catechin and epicatechin were separated by chiral capillary electrophoresis using modified cyclodextrins as chiral selectors. Various conditions for the separation system were optimized, including the pH value and the concentration of the running buffer. A baseline separation of the catechin and epicatechin enantiomers could be achieved by using 0.1 mol l⁻¹ borate buffer (pH 8.5) with 12 mmol l⁻¹ (2-hydroxypropyl)-γ-cyclodextrin as chiral selector, a fused-silica capillary with 40 cm effective length (75 μm I.D.), +18 kV applied voltage, a temperature of 20 °C and direct UV detection at 280 nm. The method was applied to different plant food samples. (+)-Catechin and (−)-epicatechin could be verified as the most common flavan-3-ols. In the case of guaraná, however, we were able to identify all four enantiomers, both (+)- and (−)-catechin and (+)- and (−)-epicatechin, as naturally occurring compounds. This finding was verified by further isolation and purification of the flavan-3-ols and subsequent LC–MS analysis. This method allows for the identification of the authenticity of guaraná through the analysis of the catechin and epicatechin enantiomers, additionally to the conventional methods like HPLC.     

Evaluation of the sensitivity of microbiological criteria for Listeria monocytogenes in detecting unsafe food according to the prevalence of the pathogen and the shelf-life of the food

The sensitivity of criteria in detecting unsafe food was studied for a hypothetical ready-to-eat food supporting growth of Listeria monocytogenes during storage. The effects of the prevalence of the pathogen and of the duration of the shelf-life on the probability for servings to be unsafe and on the probabilities of detecting unsafe food were evaluated. The results obtained in this example show that the probability for servings to be unsafe increases with the prevalence and the shelf-life while the probabilities of detecting unsafe food depend above all on the prevalence of the pathogen. The current criteria used for L. monocytogenes can then sometimes be relatively ineffective to prevent the consumption of unsafe food with regard to the shelf-life of foods. The exposure assessment approach described in this study could be used to establish shelf-lives consistent with a defined acceptable risk.     

一起米酵菌酸中毒事件的病因学诊断

目的 调查深圳市一起食用黑木耳引起的中毒事件,鉴定病原菌种类,追溯产毒菌株来源,研究米酵菌酸在体内的分布和代谢情况,为此类中毒事件的处置提供借鉴。方法 病原菌的分离和鉴定参照GB/T 4789.29—2003,同时采用基质辅助激光解吸电离-飞行时间质谱（MALDI-TOF MS）对病原菌种类进行鉴定。采用超高效液相色谱-复合线性离子阱串联质谱技术（UPLC-QTRAP-MS/MS）对黑木耳以及患者血液、肝脏和尿液、菌悬液等样品中的米酵菌酸进行检测。结果 在残留食材黑木耳、患者血液和尿液中均检出不同浓度的米酵菌酸。患者中毒5 d后进行了肝移植,坏死的肝脏中检出高浓度米酵菌酸。患者中毒9 d后,跟踪监测显示患者血液、尿液中仍然含有一定浓度的米酵菌酸。从患者采摘的干木耳及泡发的湿木耳中均分离出唐菖蒲伯克霍尔德菌,经实验室培养后,两株菌株均产出米酵菌酸。结论 本次事件是因患者采摘的干木耳带有病原菌,在长时间泡发过程中细菌产毒,患者食用含高浓度米酵菌酸的木耳后,毒素广泛分布于患者各个器官,导致多器官衰竭死亡。     

秀丽隐杆线虫在食品营养功能评价中的研究进展

秀丽隐杆线虫作为一种理想的模式生物,已被越来越多地应用于食品营养功能的评价。与细胞、小鼠等其他模型比较,线虫具有体积小、寿命短、与人类基因同源性高、研究结果易于观察且能够在实验室大批量培养等优点。文章综述了秀丽隐杆线虫在抗肥胖、抗氧化、抗衰老的食品营养功能评价中的研究方法、潜在机理及研究进展,并展望了秀丽隐杆线虫在食品抗肥胖、抗氧化、抗衰老中的研究前景。     

Chlorella vulgaris and Haematococcus pluvialis biomass as colouring and antioxidant in food emulsions

The use of microalgal biomass, a natural ingredient, to colour oil-in-water pea protein stabilised emulsions was studied. Various levels of incorporation of Chlorella vulgaris green, Chlorella vulgaris orange (after carotenogenesis), and Haematococcus pluvialis (red, after carotenogenesis) were used, resulting in a wide range of appealing colours from green to orange and pink. The colour stability of the emulsions was evaluated, through the evolution of the L^*a^*b^* parameters (CIELAB system) along 6 weeks. The primary and secondary oxidation products of the emulsions were also determined, and an enhanced resistance to oxidation was evidenced by emulsions containing microalgae. Therefore antioxidant functionality was another positive aspect of its use as an ingredient. Colour stability, a variety of attractive hues, and added resistance to oxidation ensure an adequate compromise of sensory and functional properties for these novel emulsions.     

荧光MIRA法快速检测食品中产气荚膜梭菌

目的 基于荧光多酶恒温快速扩增（MIRA）技术,建立一种快速准确检测食品中产气荚膜梭菌的方法。方法 利用产气荚膜梭菌共有α毒素编码基因plc保守序列设计引物探针,并建立和优化荧光MIRA方法;提取17种非目标菌基因组DNA进行方法特异性验证;梯度稀释目标菌基因组DNA和菌液用于方法灵敏度评价;选取4种食品进行基质干扰试验,评估方法的稳定性;检测实际样品并与国家标准方法进行比较,以验证该方法的实用性。结果 该方法特异性强,检测多种非目标致病菌均呈阴性反应;灵敏度高,以基因组DNA为模板和菌液为模板时最低检测限分别为1.05×101 fg/μL和7.5×100 CFU/mL;该方法不受基质影响,抗干扰能力强;耗时短,约20 min即可完成检测。结论 本研究中的荧光MIRA方法快速准确、灵敏度高、特异性强,可用于食品中产气荚膜梭菌的快速检测。