一起由金黄色葡萄球菌所致学校食物中毒调查分析

目的 查明一起学校食物中毒发生的原因和可疑危险因素,提出有效控制措施防止事态蔓延,为类似食源性疾病的调查和预防提供参考.方法 利用现场流行病学、食品卫生学和实验室检测等方法,开展病例主动搜索、个案调查和现场卫生学调查,采集食品、外环境和病例的标本进行实验室检测,以判断本次事件的可疑餐次和食物.结果 通过开展主动搜索,共...     

多重PCR检测4种常见食源性致病菌

目的 建立一种多重聚合酶链式反应法(multiplex polymerase chain reaction, MPCR)快速检测肉制品中金黄色葡萄球菌、沙门氏菌、志贺氏菌和单增李斯特氏菌的分析方法。方法 选取金黄色葡萄球菌nuc基因、沙门氏菌SipB基因、志贺氏菌ipaH基因、单增李斯特菌inlA基因作为目标基因, 设计4对PCR引物, 建立并优化多重PCR反应体系, 评价该体系的特异性和灵敏度, 并对人工污染的熟肉样品进行检测。结果 构建的多重PCR方法特异性强、灵敏度高, 人工污染熟肉匀浆中4种致病菌的检出限为103 CFU/mL。结论 构建的多重PCR检测方法能够快速、准确、高效地检测肉制品中金黄色葡萄球菌、沙门氏菌、志贺氏菌和单增李斯特氏菌, 为食源性疾病菌的快速检测提供参考依据。     

石家庄市零售鸡肉样品中弓形杆菌污染调查

目的调查石家庄市零售鸡肉中弓形杆菌的污染情况,为石家庄市弓形杆菌分布特征和防控提供基础数据支持。方法从石家庄市市内四区的菜市场、超市、连锁肉店随机购买零售鸡肉样品90份,应用驱动增强动力双孔滤膜法从样品中分离培养弓形杆菌,利用弓形杆菌多重聚合酶链式反应(PCR)检测及测序的方法对分离菌株进行种属鉴定,利用16S rDNA、rpoB基因测序的方法验证菌种鉴定结果。结果 90份鸡肉样品中,60份样品检出弓形杆菌86株,其中嗜低温弓形杆菌49株、布氏弓形杆菌37株,弓形杆菌检出率为66.67%(60/90)。60份阳性样品中,嗜低温弓形杆菌阳性样品45份(75.00%),布氏弓形杆菌阳性样品35份(58.33%)。嗜低温弓形杆菌和布氏弓形杆菌混合感染阳性样品20份,占比为22.22%(20/90)。不同采样点弓形杆菌检出率有较大差异。结论石家庄市零售鸡肉中弓形杆菌污染较重,嗜低温弓形杆菌污染率高于布氏弓形杆菌,两种弓形杆菌混合污染样品率较高。     

Application of electrolyzed functional water on producing mung bean sprouts

Electrolyzed functional water possesses a wide variety of antimicrobial activities. Electrolyzed functional water, which used to take place of tap water in producing mung bean sprouts, was studied in this paper. The results showed that electrolyzed water can not only reduce the quantity of microorganism on the surface of mung bean sprouts, but also promote the growth of sprouts. Further research showed that electrolyte leakage rate of mung bean soaked in electrolyzed water was the lowest, while the catalase’s activity of mung bean soaked in electrolyzed water was the highest. All of these contribute to the high activity of mung bean.     

Rapid screening and quantification of multi-class multi-residue veterinary drugs in royal jelly by ultra performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry

A simple and rapid multi-class multi-residue analytical method was developed for the screening and quantification of veterinary drugs in royal jelly by ultra performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS). A total of 90 veterinary drugs investigated belonged to more than 14 families such as lincomycins, macrolides, sulfonamides, quinolones, tetracyclines, β-agonists, β-lactams, sedatives, β-receptor antagonists, sex hormones, glucocorticoids, nitroimidazoles, benzimidazoles, nitrofurans, and the others. A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure was used for the sample preparation without solid-phase extraction step. The linearity, sensitivity, accuracy, repeatability, and reproducibility of the method were fully validated. The response of the detector was linear for each target compounds in wide concentration range (at least, two orders of magnitude) with correlation coefficient (R²) of 0.9921–0.9999. The range of the limit of quantification for these compounds in the royal jelly ranged from 0.21 to 20 μg/kg. The repeatability and reproducibility were in the range of 3.01–11.6% and 5.97–14.9%, respectively. The average recoveries ranged from 70.21 to 120.1% with relative standard deviation of 1.77–9.90% at three concentration levels. For the screening method, the data of the precursor and product ions of the target analytes were simultaneously acquired under the All Ions MS/MS mode in a single run. A homemade database including the elemental composition, accurate masses, retention time, isotopic pattern data of the target ions the characteristic in-source fragment ions was utilized for the confirmation and identification of the target compounds. The applicability of the screening method was verified by applying to real royal jelly samples, and certain veterinary drugs were detected in some cases.     

液相色谱串联质谱-同位素内标法快速测定 玉米面中的伏马菌毒素

目的建立液相色谱-串联质谱法(liquid chromatography-tandem mass spectrometry,LC-MS/MS)以同时测定玉米中3种伏马菌素(FB1,FB2 and FB3)。方法试样经50%乙腈/水溶液超声提取,离心,多功能柱净化后液相色谱/串联质谱仪直接测定,13C34-FBs内标法定量。结果加标回收率范围为75.9%~108.2%,方法检测限在0.39~0.58μg/kg之间。将本方法用于实际样品分析,67%的玉米面中同时检出3种伏马菌素(FB1,FB2 and FB3)。结论此方法简便快速,灵敏度较高,可以用于准确定量检测粮食中的伏马菌素。     

Simultaneous determination of melamine and cyanuric acid in dairy products by mixed-mode solid phase extraction and GC–MS

This report described a method for simultaneous determination of cyanuric acid (CYA) and melamine (MEL) in dairy products. The samples were extracted by a mixture of acetonitrile/water and cleaned by graphite carbon/strong cation exchange (CARB/SCX) mixed-mode solid phase extraction column. The CYA and MEL were derivatized with bis(trimethylsily1)trifluoroacetamide (BSTFA) containing 1% Trimethylchlorosilane (TMCS), and quantified with the internal standards of ¹⁵N₃-cyanuric acid and ¹³C₃-melamine by GC–MS. The results indicated that CARB/SCX mixed solid phase extraction column could be used for sample pretreatment. The fortification recoveries were 80.8–101.5%, and the relative standard deviations (RSDs) were 3.6–7.9%. The detection limits of CYA and MEL were 0.025 mg kg⁻¹ and 0.01 mg kg⁻¹ respectively.     

Reduction of Escherichia coli O157:H7 and Salmonella enteritidis on mung bean seeds and sprouts by slightly acidic electrolyzed water

High microbial populations on mung beans and its sprouts are the primary reason of a short shelf life of these products, and potentially present pathogens may cause human illness outbreak. The efficiency for inactivating Escherichia coli O157:H7 (E. coli O157:H7) and Salmonella enteritidis (S. enteritidis), which were artificially inoculated on mung bean seeds and sprouts, by means of slightly acidic electrolyzed water (SAEW, pH 5.0 to 6.5) generated through electrolysis of a mixture of NaCl and hydrochloric acid solution in a non-membrane electrolytic chamber, was evaluated at the different available chlorine concentrations (ACCs, 20–120 mg/l) and treatment time (3–15 min), respectively. The effect of SAEW treatment on the viability of seeds was also determined. Results indicate that the ACC had more significant effect on the bactericidal activity of SAEW for reducing both pathogens on the seeds and sprouts compared to treatment time (P < 0.05). The seeds and sprouts treated with SAEW at ACCs of 20 and 80 mg/l resulted in a reduction of 1.32–1.78 log₁₀ CFU/g and 3.32–4.24 log₁₀ CFU/g for E. coli, while 1.27–1.76 log₁₀ CFU/g and 3.12–4.19 log₁₀ CFU/g for S. enteritidis, respectively. The germination percentage of mung bean seeds was not significantly affected by the treatment of SAEW at an ACC of 20 mg/l for less than 10 min (P > 0.05). The finding of this study implies that SAEW with a near-neutral pH value and low available chlorine is an effective method to reduce foodborne pathogens on seeds and sprouts with less effects on the viability of seeds.     

北京市通州区食源性疾病监测病例中副溶血弧菌的病原特征分析

目的 了解通州区2015—2021年食源性疾病监测病例中副溶血弧菌的脉冲场凝胶电泳（PFGE）优势带型、耐药情况和毒力基因携带情况,为副溶血弧菌感染防控和治疗提供参考数据。方法 对2015—2021年通州区定点监测医院门诊腹泻病例的粪便样本进行副溶血弧菌分离培养,对其进行血清分型、毒力基因检测、PFGE聚类分析及药敏试验。结果 2 828份粪便标本中检出副溶血弧菌100株,检出率为3.54%,每年7~9月是检出高峰月份。不同年份副溶血弧菌检出率差异具有统计学意义（χ²=53.94,P<0.001）。100株副溶血弧菌中有一株未携带tlh基因,89.00%的菌株携带致病性毒力基因tdh。副溶血弧菌优势血清型为O3∶K6（66/100）,其次是O4∶K8（9/100）。98株菌副溶血弧菌（2株降解）PFGE分型结果显示副溶血性弧菌有39个PFGE带型,命名为V1-V39,条带相似度在79.6%~100%之间,基因分布呈高度多态性,V22和V25是通州区副溶血弧菌的优势带型。菌株对头孢唑林的耐药率最高（32.00%）,其次是氨苄西林（14.00%）和多黏菌素E（13.00%）,对四环素类、氯霉素类、氨基糖苷类、碳青霉烯类四类药物100%敏感。结论 通州区2015—2021年食源性疾病监测病例中检出的副溶血弧菌主要是O3∶K6型tdh⁺- trh^-菌株,对头孢唑林,氨苄西林和多黏菌素E耐药。PFGE图谱主要流行菌株带型相似度在93.1%以上,存在暴发风险,食品安全相关部门需做好副溶血弧菌监测及暴发预警工作,预防食源性疾病暴发。