一起阿邦尼沙门菌引起食源性疾病暴发事件流行病学分析及分子溯源调查

目的 查明引起某庙会期间发生的一起食源性疾病暴发事件的原因，确认致病危害因素及其来源，为此类事件预防控制提供参考。方法 开展现场流行病学调查，通过描述分析方法分析病例临床特征、流行病学特征及相关危害因素。开展病例对照研究确定可疑食物，通过脉冲场凝胶电泳（PFGE）法对致病因子进行相似性分析。结果 根据病例定义共收集可疑病例32例，主要临床表现为腹痛（87.50%）、腹泻（78.13%）、发热（75.00%）、头晕恶心（71.88%）。病例对照研究结果显示水煮带壳花生是危险因素（OR=4.000，95%CI：1.409~11.354）。采集28份样品中有7份分离培养出沙门菌，血清型鉴定均为阿邦尼沙门菌，经PFGE图谱分析高度相似。结论 本次事件是由阿邦尼沙门菌引起的食源性疾病暴发，可疑食物为水煮带壳花生，应加强非城区流动摊位散装食品的监管，同时加强食源性疾病监测管理工作。     

2010—2020年中国大陆生熟交叉污染导致食源性疾病暴发事件流行病学特征分析

目的 了解2010—2020年中国大陆由生熟交叉污染导致的食源性疾病暴发事件的流行病学特征,为有效防控生熟交叉污染食源性疾病暴发提供依据。方法 收集2010—2020年国家食源性疾病暴发监测系统报告的食物加工环节为生熟交叉污染导致的食源性疾病暴发事件,分析其流行病学特点。结果 2010—2020年国家食源性疾病暴发监测系统报告生熟交叉污染导致的食源性疾病暴发事件667起（1.85%）,发病11 766例,死亡4例;高发季节为第二、三季度;高发地区为南方地区;发生场所以餐饮服务场所（66.4%,443/667）和集体食堂（22.6%,151/667）为主;原因食品（除去不明食品、多种食品、混合食品）主要为肉类（26.2%,175/667）和水产类食品（14.1%,94/667）;致病微生物及毒素是导致生熟交叉污染食源性疾病暴发事件的主要致病因素,排在前3位的是副溶血性弧菌、沙门菌和金黄色葡萄球菌及其肠毒素;副溶血性弧菌事件的高危食品是水产类（55.1%,75/136）和肉类（37.5%,51/136）;沙门菌事件的高危食品为肉类（62.2%,46/74）;主要致病因子有地域性差异,其中华东、华南、西南地区副溶血性弧菌污染事件（χ²=26.3,P<0.001）和沙门菌事件（χ²=18.3,P<0.001）的构成比有差异。结论 生熟交叉污染食源性疾病事件是不容忽视的重要食品安全问题,在高温季节和南方地区,尤其要加强餐饮服务场所和集体食堂制备动物类食品时的卫生管理和食品从业人员的操作规范、微生物性食源性疾病的认知培训。     

某福利院一起肠炎沙门菌食源性疾病的调查分析

目的 对某福利院一起肠炎沙门菌食源性疾病进行调查和溯源,为研究相关食源性疾病提供参考。方法采用流行病学、食品卫生学和脉冲场凝胶电泳(PFGE)同源性分析等方法,分析本次食源性疾病事件。结果 确认本次事件中病例23名,患病率5.65%(23/407);现场采集病例肛拭子15份和厨房工作人员肛拭子3份、留样菜品3份、水果2份以及冰棒1份,其中从11份病例肛拭子中检出肠炎沙门菌,PFGE结果显示11株肠炎沙门菌的DNA条带图谱相似性为96.4%,聚类分析为同一型,结合流行病学调查,初步判断菌株来自同一克隆系。结论 综合流行病学、食品卫生学和实验室检测结果,确定为一起肠炎沙门菌引起的食源性疾病,福利院应加强对特殊人群的饮食安全管理,制定相应的食源性疾病突发事件应急处理预案,防止此类事故再发生。     

长沙市某学校一起沙门菌引起的食源性疾病事件调查分析

目的 调查分析长沙市某学校一起食源性疾病事件,为类似事件提供处置经验。方法 描述本次事件病例的流行病学特征,通过病例对照研究分析可疑食品;通过现场卫生学调查和实验室检测查找致病因子和污染食物。结果 共调查发现疑似病例54例,临床表现以腹泻（100%）、腹痛（92.59%）、发热（88.89%）为主。潜伏期为2.5~51 h,中位数13 h。病例对照分析表明2022年5月1~3日盐酥鸡店的套餐是可疑高危食物。14例病例的粪便/肛拭子样本和3批次食品样品均检出沙门菌,经脉冲场凝胶电泳分子溯源表明来自相同感染源,均为布伦登卢普型。结论 该事件是一起由布伦登卢普型沙门菌感染引起的食物中毒事件,可疑食物为水煮蛋和土豆丝。建议市场监督局加强对学校周边餐馆的监督,餐饮单位提高食品卫生知识,规范操作流程。     

一起多所幼儿园食源性疾病暴发事件的溯源分析

目的 对一起涉及多所幼儿园的食源性疾病暴发事件的可疑食品和致病因子进行溯源调查,为今后类似事件的防控和处置提供参考依据。方法 采用实时荧光PCR法、质谱技术等快速检测技术,结合分离培养、酶联免疫法（ELISA）等传统鉴定方法对3所幼儿园采集的32份样品开展病原检测。使用描述性流行病学调查方法对事件进行调查,脉冲场凝胶电泳（PFGE）方法对致病因子进行分子溯源分析。结果 3所幼儿园共有幼儿568名,62名病例,患病率为10.92%。临床症状主要为呕吐、腹泻等。从10份生物标本和某配餐公司统一配送的2份留存的拔丝肉松蛋糕检出金黄色葡萄球菌,蛋糕中金黄色葡萄球菌量分别为2.0×10⁷ CFU/g、1.4×10⁷ CFU/g,11株分离自病例和蛋糕的金黄色葡萄球菌同时检出葡萄球菌A型肠毒素基因（sea）和A型肠毒素（SEA）。PFGE指纹图谱为同一带型,提示病例和食品的分离株为同一来源。结论 本起暴发事件是由配餐公司统一配送的拔丝肉松蛋糕污染金黄色葡萄球菌产生肠毒素导致的3所幼儿园的食物中毒,应进一步加强对学校配餐食材的监管。     

2021年新乡市一起山夫登堡沙门菌食物中毒分离株的病原特征分析

目的 分析2021年新乡市一起山夫登堡沙门菌食物中毒分离株的病原特征。方法 对食物中毒事件进行流行病学调查;对采集的11份样本进行致病菌分离鉴定;对分离出的10株沙门菌进行血清学分型、药敏试验、5种毒力岛（SPIs）特征基因片段（mogA、sseL、mgtC、bcfA、araB）检测及脉冲场凝胶电泳（PFGE）分型分析。结果 10株沙门菌血清抗原式均为1,3,19;g,s,t,即山夫登堡沙门菌。10株沙门菌对头孢唑啉、卡那霉素、庆大霉素、阿米卡星的耐药率为100%,其中从患者粪便中分离出的2株对氨苄西林、四环素、多西环素、氯霉素、复方新诺明的耐药率为100%。PFGE图谱聚类分析显示,10株菌（2株病例株,5株食品株,3株环境株）之间条带无差异,高度同源。10株菌中5种毒力岛特征基因片段均检出。结论 本起食物中毒事件致病因子为山夫登堡沙门菌,该菌携带5种毒力岛特征基因片段,2株病例株沙门菌具有多重耐药性,建议相关部门高度关注。     

2020年贵阳市城区部分集贸市场即食食品微生物污染情况调查

目的 了解集贸市场即食食品微生物污染情况,分析食源性沙门菌菌株生物学特征,评价食品卫生状况及致病风险。方法 随机选取人群消费较集中的5家大型集贸市场,按照国家食品安全标准对其售卖的即食食品进行食品微生物检测,同时对沙门菌血清型、抗生素耐药性及PFGE聚类进行分析。结果 131份即食食品中大肠菌群检出率62.59%（82/131）,并检出了沙门菌、蜡样芽孢杆菌、金黄色葡萄球菌等致病微生物。沙门菌血清型多样,其PFGE图谱较分散,菌株出现多重耐药。结论 即食食品卫生状况普遍较差,生肉食品中检测出沙门菌,容易与即食食品发生交叉污染而引发食源性疾病,应加强即食食品及生肉制品的管理。     

2021年贵州省食源性疾病主动监测分离沙门菌耐药及分型特征

目的 了解2021年贵州省食源性疾病主动监测分离沙门菌的血清型、耐药和分子分型特征。方法 对全省2021年食源性疾病主动监测腹泻病例中分离的164株沙门菌采用玻片凝集法进行血清学分型，采用微量肉汤稀释法测定菌株对14种抗生素的最小抑菌浓度（MIC）值，采用脉冲场凝胶电泳（PFGE）进行分子分型。结果 164株沙门菌可分为25种血清型，优势血清型为鼠伤寒沙门菌（76，46.34%）、肠炎沙门菌（25，15.24%）和爪哇安纳沙门菌（15，9.15%）。164株沙门菌耐药率为100%，多重耐药率达86.59%；其中对氨苄西林、四环素和萘啶酸耐药率较高，分别为95.12%（156/164）、78.05%（128/164）和63.41%（104/164）。72株鼠伤寒沙门菌PFGE聚类分析后共分为58种指纹图谱，24株肠炎沙门菌有12种指纹图谱，15株爪哇安纳沙门菌有3种指纹图谱。结论 贵州省腹泻患者沙门菌血清型种类较多，多重耐药现象严重，PFGE指纹图谱表现出遗传多样性。应加强对沙门菌的耐药监测，尤其是优势血清型鼠伤寒沙门菌的临床用药。     

预包装熟肉制品生产加工过程沙门菌污染状况及病原学特征研究

目的 了解预包装熟肉制品生产加工过程各环节中沙门菌污染状况,并分析分离株的分子特征及耐药性。方法 按照国家《熟肉制品（预包装）生产加工过程监测工作手册》采样要求,2015—2017年在德州某预包装熟肉制品厂采集环境样品和熟肉样品共460份,依据现行有效的GB 4789.4—2016进行沙门菌分离鉴定;用血清凝集法对沙门菌进行血清分型;用脉冲场凝胶电泳（PFGE）和多位点序列分型（MLST）法对沙门菌进行分子分型分析;采用微量肉汤稀释法对15种抗生素进行耐药性检测。结果 460份样品中沙门菌检出率为5.65%（26/460）,2016年沙门菌的检出率最高（7.65%,14/183）,不同年份沙门菌检出率差异无统计学意义（χ²=2.82,P>0.05）;中间产品中沙门菌的检出率最高,不同样品属性沙门菌检出率差异有统计学意义（χ²=64.16,P<0.05）;仅在生制品加工车间检出沙门菌,不同车间沙门菌检出率差异有统计学意义（χ²=78.08,P<0.05）。26株沙门菌共分为6个血清型,肠炎沙门菌最多,占53.85%（14/26）。26株沙门菌经PFGE分型后获得12种带型,以S4型为主;经MLST分型共获得5种ST型,ST11为优势型别。26株分离株中有22株对不同的抗生素有耐药性,耐药率最高的是氨苄西林,为73.08%（19/26）,多重耐药率（耐3种及以上抗生素）为73.08%。结论 熟肉制品加工过程中沙门菌污染主要集中在加工过程的原辅料和中间产品环节,产品蒸煮后污染状况可被有效控制。     

重庆市某区一起肠炎沙门菌引起的食源性疾病暴发事件调查分析

目的 对一起因食用被肠炎沙门菌污染面包引起的食源性疾病暴发事件进行调查分析,为今后处置类似事件提供依据。方法 利用描述性流行病学方法分析病例的临床特征、流行病学分布及相关危险因素,开展回顾性队列研究确定病因食品,采集病例和食堂从业人员生物标本、剩余食品和环境样品进行实验室检验,结合卫生学调查情况,综合分析暴发事件的发生原因。结果 回顾性队列研究显示2021年5月20日重庆市某食品厂生产的某批次预包装面包为可疑食物,在食用该批次面包的73人中,有55人发病,患病率为75.34%,潜伏期中位数为15 h,同时,在剩余食品、相关环境样品、病人肛拭子中均检出肠炎沙门菌。结论 本次事件是一起因进食受肠炎沙门菌污染的面包导致的食源性疾病暴发事件。     

Arsenic content of some edible mushroom species

The arsenic contents of 162 fruit body samples of 37 common edible mushroom taxa were analyzed. The samples were gathered from different habitats of Hungary (mainly from mountains) between 1984 and 1999. The arsenic content of the samples was measured by the inductively coupled plasma spectrometry method. Very low [lower than 0.05 mg/kg dry matter (DM)] concentrations were found in the samples of 13 taxa, while higher (or very high) contents were quantified in other common taxa (the highest arsenic content was recorded in the fruit body of Laccaria amethysthea at 146.9 mg/kg DM). The species of eight genera (Agaricus, Calvatia, Collybia, Laccaria, Langermannia, Lepista, Lycoperdon, Macrolepiota) belong to the so-called accumulating taxa, and this tendency is evident on all habitats. This arsenic accumulation capability is found in two orders of Basidiomycetes (Agaricales and Gasteromycetales), which is to say this phenomenon occurs in the families Agaricaceae, Tricholomataceae and Gasteromycetaceae. The accumulating taxa found all have a saprotrophic type of nutrition; arsenic accumulation is not detectable in xilophagous or in mycorrhizal species. The consumption of the accumulating species found has only a low toxicological risk for three reasons: the consumed fresh fruit bodies contain about a tenfold lower arsenic level than the dried ones, the majority of arsenic occurs not in poisonous inorganic, but in less dangerous (or not poisonous) organic forms, and the frequency of consumption is low.     

Organization and localization of the dnaA and dnaK gene regions on the multichromosomal genome of Burkholderia multivorans ATCC 17616

The Burkholderia multivorans strain ATCC 17616 carries three circular chromosomes with sizes of 3.4, 2.5, and 0.9 Mb. To reveal the distribution and organization of the genes for fundamental cell functions on the genome of this bacterium, the dnaA and dnaK gene regions of ATCC 17616 were cloned and characterized. The gene organization of the dnaA region was rnpA-rmpH-dnaA-dnaN-gyrB with a single consensus DnaA-binding box (TTATCCACA) between the rmpH and dnaA genes. This intergenic region, however, did not work as an autonomously replicating sequence in ATCC 17616. On the other hand, the gene organization of the dnaK region was grpE-orf1 (gene for thioredoxin homologue)-dnaK-dnaJ-pabB (gene for p-aminobenzoate synthetase component homologue). A putative heat-shock promoter that showed good homology to the sigma32-dependent promoter consensus sequence in Escherichia coli was found upstream of the grpE gene, suggesting that these five genes constitute an operon. In M9 succinate minimal medium the dnaJ mutant grew more slowly than the wild-type strain, indicating that this operon is functional. Pulsed-field gel electrophoresis and Southern blot analyses indicated that both the dnaA and dnaK gene regions exist as single copies on the 3.4 Mb chromosome.     

Microbial profiles of frozen trimmings and silver sides prepared at Indian buffalo meat packing plants

To assess microbiological quality of buffalo meat trimmings (TT = 114) and silver sides (SS = 41), samples were collected from four different Indian meat packing plants. The aim of this study was: (i) to evaluate standard plate count (SPC), psychrotrophic count (PTC), Enterococcus feacalis count (EFC), Staphylococcus aureus count (SAC) and Escherichia coli count (ECC) and the presence of Salmonella spp. and Listeria monocytogenes; and (ii) also to determine vero toxic E. coli (VTEC) by polymerase chain reaction (PCR). TT samples had significantly higher (P < 0.001) SPC, PTC, EFC, and SAC than SS, while across the meat types there was no difference (P > 0.05) in ECC. E. coli was recovered from 32.4% TT and 19.5% SS samples. The prevalence rate of Salmonella spp. and L. monocytogenes in TT was 1.75% and 0.87%, respectively. But no SS sample was found to be positive for any of these two pathogens. VTEC was found in 2.58% of all the tested samples. This finding suggests that TT contain higher microbes but only small numbers of pathogens of latent zoonotic importance. The present study confirmed the importance of maintaining good process hygiene at meat plants for microbiological status of buffalo meat.     

Susceptibility of stored product insects to high concentrations of ozone at different exposure intervals

Ozone is a highly reactive gas with insecticidal activity. Past studies have indicated that ozone technology has potential as a management tool to control insect pests in bulk grain storage facilities. The objective of this study was to determine the efficacy of short periods of exposure to high ozone concentrations to kill all life stages of red flour beetle (Tribolium castaneum (Herbst)) (Coleoptera: Tenebrionidae), and Indianmeal moth (Plodia interpunctella (Hübner)) (Lepidoptera: Pyralidae), adult maize weevil (Sitophilus zeamais (Motsch.)) (Coleoptera: Curculionidae) and adult rice weevil (S. oryzae (L)) (Coleoptera: Curculionidae). Insects were treated with six ozone concentrations between 50 and 1800 ppm. The specific objective was to determine minimal time needed to attain 100% mortality. The most ozone-tolerant stages of T. castaneum were pupae and eggs, which required a treatment of 180 min at 1800 ppm ozone to reach 100% mortality. Eggs of P. interpunctella also required 180 min at 1800 ppm ozone to reach 100% mortality. Ozone treatments of 1800 ppm for 120 min and 1800 ppm for 60 min were required to kill all adult S. zeamais and adult S. oryzae, respectively. The results indicate that high ozone concentrations reduce the treatment times significantly over previously described results. Our results also provide new baseline information about insect tolerance to ozone treatment.     

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 Zataria multiflora Boiss. essential oil and nisin on Salmonella typhimurium and Staphylococcus aureus in a food model system and on the bacterial cell membranes

The effects of different concentrations of Zataria multiflora Boiss. essential oil (EO: 0, 5, 15 and 30 μl 100 ml⁻¹) and nisin (N: 0, 0.25 and 0.5 μg ml⁻¹), temperatures (T: 25 and 8 °C), and storage times (up to 21 days) on growth of Salmonella typhimurium and Staphylococcus aureus in a commercial barley soup were evaluated in a factorial design study. The growth of S. typhimurium was significantly (P < 0.05) decreased by EO concentrations and their combinations with N concentrations at 8 °C. For S. aureus, the viable count was significantly (P < 0.05) inhibited by EO and N concentrations and their combinations, incubated at both storage temperatures. The mechanism of the antimicrobial action of EO, N, and their combinations against cell membranes of the tested organisms were also studied by measurement of the release of cell constituents and by the electronic microscopy observations of the cells. The significant increase of the cell constituents’ release of both organisms was observed as a result of treatments with EO and EO in combination with N. Electronic microscopy observations revealed that the cell membranes of S. typhimurium treated by EO and EO in combination with N were significantly damaged, while cells treated with only N looked similar to untreated cells. The electron micrographs of treated cells of S. aureus with EO, N, and their combination also showed important morphological damages and disrupted membranes.     

Formation of cereulide and enterotoxins by Bacillus cereus in fermented African locust beans

Afitin, iru and sonru are three spontaneously fermented African locust bean Benin condiments. The fermentation processes are exothermic, with temperatures mostly being above 40 °C. A total of 19 predominant Bacillus cereus isolates from afitin, iru and sonru, were investigated. The enterotoxin genes nhe (A, B, C) were present in all 19 isolates, the hbl (A, C, D) in one (afitin), and the cytK gene in three isolates (afitin). Levels of cytotoxicity to Vero cells and NheA production in BHI-broth was within the range of known diarrheal outbreak strains. Autoclaved cooked African locust beans inoculated with emetic (cereulide producing) B. cereus Ba18H2/RIF supported growth at 25, 30 and 40 °C with highly different maximum cereulide productions of 6 ± 5, 97 ± 3 and 0.04 ± 0.02 μg/g beans, respectively (48 h). For non-autoclaved cooked beans inoculated with 2, 4 and 6 log₁₀B. cereus Ba18H2/RIF spores/g beans, cereulide production was 5 ± 4, 64 ± 8 and 69 ± 34 μg/g beans, respectively at 24 h, while it was 70 ± 43, 92 ± 53 and 99 ± 31 μg/g at 48 h of fermentation at 30 °C. Even though high toxin levels were observed, to date there are no known reports on diarrhea or vomiting due to the consumption or afitin, iru and sonru in Benin, which also according to the present study is likely to be expected from the low levels of cereulide produced at 40 °C.     

Cloning and expression analysis of two catalase genes from Aspergillus oryzae

Fungi contain distinct genes encoding the same class of enzyme that are differentially regulated according to conditions. We cloned two catalase genes, catA and catB, from Aspergillus oryzae. The catA gene predicts a 747-amino-acid polypeptide sharing 81% identity with Aspergillus fumigatus catalase (catA) and 77% with Aspergillus nidulans catalase (catA). The catB gene predicts a 725-amino-acid polypeptide sharing 82% identity with A. fumigatus catalase (catB) and 75% with A. nidulans catalase (catB). However, the catA and catB genes share little homology (41%) with one another, suggesting that each gene belongs to a distinct gene family. Overexpression studies demonstrated that both genes encode a functional catalase. Promoter assays indicated that the catA gene is developmentally regulated as it was preferentially expressed in solid-state cultures undergoing sporulation. However, its expression was not affected by hydrogen peroxide treatment. Conversely, the catB gene was highly expressed under all culture conditions tested, and it was induced by hydrogen peroxide treatment. These results suggest that the catB gene may be mainly used for detoxification of oxidative stress while the catA gene may have another role such as chaperoning proteins in the spore.