傅立叶变换红外光谱技术对6种致病性大肠埃希氏菌快速分型的研究

目的建立肠致病性大肠埃希氏菌(Enteropathogenic E.coli,EPEC)、肠产毒性大肠埃希氏菌(Enterotoxigenic E.coli,ETEC)、肠侵袭性大肠埃希氏菌(Enteroinvasive E.coli,EIEC)、肠黏附性大肠埃希氏菌(Enteroadhesive E.coli,EAEC)、肠出血性大肠埃希氏菌(Enterohmorrhagic E.coli,EHEC)、弥散粘附性大肠埃希氏菌(Diffusely adherent E.coli,DAEC)6种致病性大肠埃希氏菌的傅立叶变换红外光谱(Fourier transform infrared spectroscopy,FT-IR)数据库及FT-IR分型方法。方法应用FT-IR技术对6种致病性大肠埃希氏菌进行指纹图谱数据采集并对其进行基线校正、归一化等处理,应用化学计量学方法对光谱数据进行分析。结果本研究建立了6种致病性大肠埃希氏菌的FT-IR光谱数据库,实现了对6种可疑目标大肠埃希氏菌鉴定;建立了主成分分析(principal component analysis,PCA)和分级聚类分析(hierarchical cluster analysis,HCA)2种模型,成功实现了对6种致病性大肠埃希氏菌的快速分型。结论 FT-IR分析方法快速、简便、易操作,结果重现性好,是一种鉴定6种致病性大肠埃希氏菌的有效方法。     

ATP生物发光法快速测定物体表面的菌落总数

以大肠埃希氏菌作为指示菌考量了ATP生物发光法测定物体表面卫生状况的准确性,并在实验室内模拟食品企业卫生管控,采用ATP生物发光法对具有代表性的台面进行细菌总数测定,与国家标准微生物检测方法进行了比对分析。结果显示:大肠埃希氏菌的ATP荧光值与菌落总数的线性相关性良好,相关系数R2为0.982 6;以实验室内指定台面作为盲样进行对比测定,其ATP荧光值与菌落总数的线性相关性良好,相关系数R2达到0.915 9,说明ATP生物发光法能够准确评估和测定物体表面的卫生状况。     

3种方法检测食品中致泻大肠埃希氏菌检测能力验证结果分析

目的提高食品中致泻大肠埃希氏菌的检测能力,促进实验室检测能力的提高。方法参照GB4789.6-2016《食品微生物学致泻大肠埃希氏菌检验》方法进行检测,采用VITEK 2 Compact全自动细菌鉴定系统进行生化鉴定、血清学鉴定,对可疑菌落进行普通PCR确证试验。同时使用多重实时荧光PCR法以及基质辅助激光解析电离飞行时间质谱(matrix-assisted laser desorption ionizationtime-of-flight mass spectrometry,MALDI-TOF-MS)分析鉴定可疑菌落。结果国标法和多重实时荧光PCR法能准确鉴定出目标菌,MALDI-TOF-MS可以检测大肠埃希氏菌,但无法区分致泻大肠埃希氏菌和肠出血性大肠埃希氏菌。结论 3种方法各有优劣,同时使用,综合判断,能确保试验结果准确快速。     

2016年江苏省食源性疾病患儿中致泻大肠埃希氏菌毒力基因分布与耐药性特征

目的 了解江苏省食源性疾病患儿中致泻大肠埃希氏菌的流行状况、不同毒力基因型的分布和对抗生素的敏感性特征。方法 从江苏省各设区市的三甲医院共收集3566例食源性疾病患儿的粪便或肛拭子标本进行致泻大肠埃希氏菌检测, 用实时荧光定量PCR进行毒力分型, 用微量肉汤稀释法进行药敏实验。结果 江苏省食源性疾病患儿中, 共检出致泻大肠埃希氏菌104株, 总检出率为2.9%(104/3566)。在5种毒力基因型致泻大肠埃希氏菌中, 肠聚集性大肠埃希氏菌、肠致病性大肠埃希氏菌是主要的毒力基因型, 分别占61.5%(64/104)、26.9%(28/104)。致泻大肠埃希氏菌对氨苄西林耐药率最高, 达71.2%, 其次为四环素和萘啶酸, 分别为59.6%和54.8%。未发现亚胺培南耐药菌株。多重耐药率为75.0%。结论 肠聚集性大肠埃希氏菌是导致江苏省儿童食源性疾病最主要的致泻大肠埃希氏菌。约95%以上的致泻大肠埃希氏菌对头孢他啶、头孢西丁敏感, 100%对亚胺培南敏感。耐药率及多重耐药率高, 应加强致泻大肠埃希氏菌耐药性监测及临床抗生素合理使用。     

优化生活饮用水中微生物检测的处理方法

目的优化生活饮用水微生物检测中总大肠菌群、耐热大肠菌群、大肠埃希氏菌滤膜法的稀释及过滤方法,并验证方法可行性。方法待测水样稀释1倍,旋转加入稀释液过滤,再依据国家标准GB/T5750.12-2006《生活饮用水标准检验方法微生物指标》滤膜法的条件,培养、验证;同时按照该方法处理能力验证待测水样,检验并上报结果。结果总大肠菌、耐热大肠菌、大肠埃希氏菌菌落在滤膜上生长均匀,可计数,能力验证结果|Z|均小于2。结论通过能力验证证实本实验稀释方法合理,过滤手段有效,适用于复杂水样总大肠菌群、耐热大肠菌群、大肠埃希氏菌的检测。     

5 类致泻性大肠埃希氏菌多重荧光PCR检测方法的建立

目的：建立快速检测和鉴别5?类致泻大肠埃希氏菌的多重实时荧光聚合酶链式反应（polymerase chain reaction,PCR）方法。方法：根据5?类致泻大肠埃希氏菌的11?组毒力基因eae、stx1、stx2、ipaH、uidA、estla、estlb、aggR、pic、elt、astA建立多重实时荧光PCR方法,该方法包括A、B?2?个反应体系,可分别检测肠致病性大肠埃希氏菌、肠出血性大肠埃希氏菌、肠侵袭性大肠埃希氏菌、肠产毒大肠埃希氏菌、肠聚集性大肠埃希氏菌,优化反应体系的引物、探针浓度以及PCR反应条件,并对该方法的灵敏度和特异性进行检测。结果：11?组基因的探针和引物均可特异性地扩增相应的基因片段,A体系检测下限可达到2.6×104?copies/反应,B体系检测下限可到达2.2×104?copies/反应。结论：本研究所建立的多重实时荧光PCR方法可以对同一样本同时采用A、B?2?个反应体系进行检测,不但可以确定待测样本是否为大肠埃希氏菌,而且还能判定其致病型别。为大肠埃希氏菌的临床检测、疾病预防以及爆发溯源等提供参考。     

中央厨房熟肉制品的卫生状况调查分析

为了解广州及周边地区中央厨房熟肉制品的卫生状况,2017年对广州、佛山、东莞、中山、惠州和台山等6个区域的21家中央厨房企业单位共调查熟肉制品70批次,分别开展菌落总数、大肠埃希氏菌、沙门氏菌、金黄色葡萄球菌、大肠埃希氏菌O157和单核细胞增生李斯特氏菌6项微生物指标的检验。结果显示,本次调查的中央厨房熟肉制品卫生状况总体情况运行良好,但仍然存在着微生物污染等风险安全隐患问题,有必要持续对中央厨房熟肉制品实行监测管控。     

6类致泻大肠埃希氏菌多重PCR检测体系的建

目的 构建食源性致泻大肠埃希氏菌高效、快速、特异性强的检验方法。方法 根据6类致泻大肠埃希菌11种毒力基因引物, 采用煮沸法制备细菌基因组DNA作为模板构建致泻大肠埃希氏菌单菌多重PCR检测体系; 采用试剂盒法制备细菌基因组DNA作为模板构建6类菌十重PCR检测体系, 对2种检测体系进行优化并对其进行特异性、重复性验证。结果 构建了6类致泻大肠埃希氏菌多重PCR检测体系, 包括单菌多重PCR、6类菌十重PCR检测体系。仅6类致泻大肠埃希氏菌阳性菌株有特异性条带产生; 不同类型致泻大肠埃希氏菌菌株均检出其特异性阳性条带, 该多重PCR检测方法重复性好, 稳定性强。结论 该方法可高效快速地确定待测样是否为大肠埃希氏菌及其致病型, 为食品中致泻大肠埃希氏菌的监控、预警及爆发引起食物中毒后溯源等提供参考。     

对某市生活饮用水微生物指标的监测分析与 风险评估

目的通过对某市2014年生活饮用水中微生物指标的监测分析与风险评估,了解该市水质安全状况,便于水质监管部门进行预防控制。方法在该市的9个监测点随机抽取生活饮用水样本676个,采用国标方法对菌落总数、总大肠菌群、耐热大肠菌群、大肠埃希氏菌4个微生物指标进行检测分析,并采用多维灰聚类方法对不合格率最高的监测点7#的不合格样本进行风险评估。结果该市生活饮用水水样的总不合格率为55.03%,菌落总数和总大肠菌群是导致不合格的主要原因。监测点7#的不合格样本中,低风险类型占79%,中风险类型占16%,高风险类型占5%。结论该市生活饮用水存在发生肠道传染病的风险,需要采取措施进行改进。     

6类致泻大肠埃希氏菌多重PCR检测体系的建立

目的构建食源性致泻大肠埃希氏菌高效、快速、特异性强的检验方法。方法根据6类致泻大肠埃希菌11种毒力基因引物,采用煮沸法制备细菌基因组DNA作为模板构建致泻大肠埃希氏菌单菌多重PCR检测体系;采用试剂盒法制备细菌基因组DNA作为模板构建6类菌十重PCR检测体系,对2种检测体系进行优化并对其进行特异性、重复性验证。结果构建了6类致泻大肠埃希氏菌多重PCR检测体系,包括单菌多重PCR、6类菌十重PCR检测体系。仅6类致泻大肠埃希氏菌阳性菌株有特异性条带产生;不同类型致泻大肠埃希氏菌菌株均检出其特异性阳性条带,该多重PCR检测方法重复性好,稳定性强。结论该方法可高效快速地确定待测样是否为大肠埃希氏菌及其致病型,为食品中致泻大肠埃希氏菌的监控、预警及爆发引起食物中毒后溯源等提供参考。     

Microbiological evaluation of bottled non-carbonated ("still") water from domestic brands in Greece

The microbiological quality of 1,527 samples of bottled non-carbonated ('still') mineral water, purchased from retail outlets and derived from 10 manufacturing companies in Greece, was investigated during the period 1995-2003. Applying the membrane filter technique, the aliquots of water samples (250 ml) were analyzed for the presence and enumeration of total coliforms, Escherichia coli, Enterococcus spp. and Pseudomonas aeruginosa. Also, aerobic bacteria were counted as Heterotrophic Plate Count (HPC) ml(-1) at 22 and 37 degrees C. Positive samples for the parameters tested varied significantly among brands with an overall percentage of 13.95% bottled water samples noncompliant with the Greek water regulation. Microorganisms isolated from the samples tested were identified as species of Pseudomonas, Aeromonas, Pasteurella, Citrobacter, Flavobacterium, Providencia and Enterococcus. The most frequent isolated microorganism during the period of the study was P. aeruginosa. Generally, bacterial load of the samples tested ranged in low levels. The purpose of the current study was to evaluate the microbiological quality of the bottled water provided by domestic brands in the Greek market during the period 1995-2003.     

High hydrostatic pressure inactivation of vegetative microorganisms, aerobic and anaerobic spores in pork Marengo, a low acidic particulate food product

To prolong the shelf-life of particulate food products, high pressure processing is one of the emerging technologies to be studied as an alternative to classical pasteurization and sterilization by heat. Pork Marengo (a low acidic, partially prepared stew of pieces pork, carrots and peas) was inoculated with several strains of sporulating and vegetative microorganisms. The microbial spoilage of the product was evaluated after a high pressure treatment of 400 MPa during 30 min at, respectively, 20 and 50 °C. Several Clostridium spp. and Bacillus spp. survived the treatment, and the Gram-positive cocci Enterococcus faecalis and Staphylococcus aureus were revealed to be more pressure resistant than Saccharomyces cerevisiae and the Gram-negative bacteria Pseudomonas fluorescens and Escherichia coli. The high pressure treatment at 20 °C demonstrated that high pressure processing (HPP) of neutral-pH foods cannot rely on pressure alone as a pasteurization/sterilization process. Another physical agent like heat is needed. High pressure treatment at 50 °C demonstrated that heat transfer limitations in particulate food products still can trouble their successful pasteurization/sterilization.     

The presence of Enterococcus, coliforms and E. coli in a commercial yeast manufacturing process

This study evaluated a typical commercial yeast manufacturing process for bacterial contamination. Product line samples of a commercial yeast manufacturing process and the corresponding seed yeast manufacturing process were obtained upstream from the final compressed and dry yeast products. All samples were analysed before (non-PI) and after preliminary incubation (PI) at 37 degrees C for 24 h. The PI procedure was incorporated for amplification of bacterial counts below the lower detection limit. Enterococcus, coliform and Escherichia coli counts were quantified by standard pour-plate techniques using selective media. Presence at all stages and progressive increases in counts of Enterococcus, coliforms and E. coli during processing in the commercial manufacturing operation suggested that the primary source of contamination of both compressed and dry yeast with these bacteria was the seed yeast manufacturing process and that contamination was amplified throughout the commercial yeast manufacturing process. This was confirmed by surveys of the seed yeast manufacturing process which indicated that contamination of the seed yeast with Enterococcus, coliforms and E. coli occurred during scale up of seed yeast biomass destined as inoculum for the commercial fermentation.     

Quality of minimally processed carrots as affected by warm water washing and chlorination

Different applications of cold and warm tap water (4 °C and 50 °C) with and without chlorination, respectively, in the washing of uncut peeled carrots (Daucus carota L.) were conducted, and their effects on sensory and microbiological properties during storage for 9 days at 4 °C were assessed. To minimise cross-contamination of almost sterile inner root parts with the highly contaminated outer cortex during processing the peeled carrots were washed prior to cutting. The washing treatments were carried out using a commercial processing line, thus facilitating the scale-up to industrial production. Populations of aerobic mesophilic bacteria, lactic acid bacteria and enterobacteria on these minimally processed carrots were determined, and the sensorial quality of shredded carrots was evaluated by a sensory panel throughout storage. Additionally, colour, texture, sugars, and trichloromethanes were analysed. Washing uncut carrots with cold chlorinated water (200 mg/l, 4 °C) and warm tap water (50 °C) ensured sugar retention and reduced aerobic mesophilic bacteria by 1.7 and 2.0 log₁₀ colony forming units per gram (cfu/g), respectively, while washing with warm chlorinated water (200 mg/l) resulted in a 2.3 log₁₀ cfu/g reduction. By-product formation due to chlorination was negligible. Sensorial properties of the latter samples were slightly affected. It was shown that both washing uncut knife-peeled carrots with cold chlorinated water (4 °C) and warm tap water (50 °C), respectively, provided good microbiological safety paired with improved sensorial properties. Moreover, fresh-like character of the products was retained, as indicated by the persisting respiration of the living tissues.Industrial relevanceMinimally processed vegetables are an increasing market. Shelf-life extension and consumer safety are of immense relevance for the fresh-cut industry; therefore, the application of antimicrobial agents such as chlorine is widespread. However, various consumer groups object to the use of chlorinated water. The present study aimed at comparing the efficacy of cold and warm tap water with and without chlorination, respectively, in washing uncut carrots during the production of shredded, packaged carrots while operating on pilot-plant scale under conditions of industrial practice. In view of microbial reduction and maintenance of sensory properties, the use of cold chlorinated water and warm tap water, respectively, proved to be effective for washing peeled carrots. By-product formation due to chlorination was negligible.     

2015年内蒙古地区31批保健食品中污染菌的分离与鉴定

目的 对保健食品中的污染菌进行分离和鉴定。方法 按照GB 4789《食品安全国家标准 食品微生物学检验》对31批次保健食品进行检验, 采用全自动细菌鉴定系统对污染菌进行鉴定。结果 从31批次的保健食品中分离、鉴定出64株污染菌, 在沙门氏菌、志贺氏菌、金黄色葡萄球菌和溶血性链球菌的检验中未检出目的菌, 但分离得到致病菌和条件致病菌, 分别是阴沟肠杆菌、肺炎克雷伯菌、气味沙雷菌、温和气单胞菌、赫氏埃希菌、阪崎肠杆菌、非脱羧勒菌、泛菌属、缓慢葡萄球菌、浅绿气球菌、哥伦比亚肠球菌、腐生葡萄球菌、产色葡萄球菌、溶血葡萄球菌、铅黄肠球菌、屎肠球菌、以及枯草/解淀粉/萎缩芽孢杆菌、死谷芽孢杆菌、短小芽孢杆菌、凝结芽孢杆菌以及蜡样/苏云金/蕈状芽孢杆菌。结论 各种致病菌及条件致病菌的检出, 对消费者健康存在潜在的风险。通过分析污染菌的来源及危害, 提出提高保健食品卫生质量的建议, 为保健食品的生产、消毒灭菌、卫生学检验及监督管理等方面提供参考。     

食品加工用水微生物检测的重要性

食品加工业是用水型工业之一,水质的优劣对食品安全至关重要,对加工用水进行安全卫生控制是生产过程控制的重要环节。微生物污染是食品加工用水最主要的安全隐患之一,我国食品加工用水微生物污染风险高、概率大,每年因食品加工用水微生物污染导致的产品质量问题不在少数,给企业造成了巨大的经济损失。食品加工企业对加工用水的质量控制必不可少,尤其是加工用水的微生物检测能力会影响最终产品的安全性。企业应打破只重视原料、过程产品和最终产品微生物检测的老思路,注意监控加工用水的微生物污染情况。参加水质微生物能力验证能够加强企业实验室对生产加工用水的自我检测能力,确保检测结果的准确性和认可性,对提高产品质量和品质有促进作用。     

2013—2020年广州市市售生食动物性水产品食源性致病菌监测结果分析

目的 了解2013—2020年广州市市售生食动物性水产品中食源性致病菌污染状况及分布特点。 方法 2013—2020年共采集631份生食动物性水产样品, 进行沙门氏菌、单核细胞增生李斯特氏菌、副溶血性弧菌、创伤弧菌、霍乱弧菌和致泻性大肠埃希氏菌等食源性致病菌检测。结果 检出食源性致病菌阳性样品90份, 总检出率为14.26%。生食动物性淡水产品和生食动物性海产品食源性致病菌检出率差异有统计学意义, ?2=160.375, P<0.001。生食动物性淡水产品检出率较高, 达到了45.70%。6种食源性致病菌检测结果显示, 创伤弧菌检出率最高, 达到9.51%, 其次是副溶血性弧菌5.86%, 沙门氏菌1.90%。第3季度检出率最高, 为16.15%, 最低的是第1季度(11.36%)。餐饮单位所售生食动物性水产品食源性致病菌检出率最高(21.90%), 其次为超市(7.69%), 网店和农贸肉菜市场所售商品无检出。结论 广州市市售生食动物性水产品存在不同程度的食源性致病菌污染, 致病菌污染主要以创伤弧菌、副溶血性弧菌为主, 生食动物性淡水产品污染情况更严重, 相关政府部门应加强监管, 开展健康宣传教育, 预防食源性疾病的发生。     

Storage stability of an egg yolk cream formulation: texture and microbiological assessment

BACKGROUND: Egg yolk cream is confectioned with egg yolk, sugar and water. Pasteurized liquid eggs may be used in order to increase product safety, although these samples may differ from the classic ones produced with raw eggs. The objective was to evaluate and compare the stability (physicochemical characteristics, such as texture assessment, pH and water activity, and microbiological assessment) of a classic formulation and an alternative one produced with pasteurized eggs, during storage at 6, 26, 30 and 37 °C. RESULTS: From a microbiological point of view (mesophile and psychrotrophic activity), no differences were observed in either formulations. At 6 and 26 °C, rheological behaviour of both formulations remained approximately constant. At 30 and 37 °C, differences were only detected after 20 days of storage. Texture was better retained in samples prepared with pasteurized eggs, while the classic samples showed an increase in complex viscosity. CONCLUSION: Cream storage did not require refrigeration. In terms of texture and microbial load, results obtained at 6 and 26 °C were identical. The formulations only differed in texture when stored at 30 and 37 °C and for long periods. These conclusions may allow reduction of costs related to refrigerated distribution/storage of either classic or alternative formulations. Copyright © 2008 Society of Chemical Industry     

2016年广东省6类食品不同微生物污染情况分析

目的 为了解广东省流通食品的微生物污染状况。方法 采用GB 4789-2010《食品安全国家标准 食品微生物学检验》对2016年检验的6类食品进行微生物（菌落总数、大肠菌群、霉菌和酵母菌、致病菌）检验,对检验结果进行统计分析。结果 3216份样品中共检出不合格样品39份,总体合格率为98.79%。不同微生物项目的检验结果中,菌落总数的合格率相对最低,为99.19%。检验的6类食品中速冻食品、方便食品和水产制品检出不合格样品,方便食品的合格率（97.2%）相对最低。结论 广东省食品微生物污染整体状况较好,建议对微生物污染风险较高的方便食品、水产制品进行重点关注,采取有效措施降低食品微生物污染的风险。     

自然发酵黄豆酱的微生物安全性的分析

对从11份农家和7份市场上销售的自然发酵黄豆酱样品进行了微生物的安全性检验和部分理化指标的测定，检验的项目包括细菌落总数、芽孢杆菌总数、大肠杆菌、沙门氏菌、志贺氏菌、腊样芽孢杆菌、金黄色葡萄球菌和肉毒梭菌。实验结果表明，所分析样品中菌落总数超过10^4个/g的样品有89％，腊样芽孢杆菌的检出率为30％，但含量不高，豆酱中的细菌总数除了与生产环境有关外，与产品的水分活度的相关性很大。