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。     

2014—2018年江西省食源性疾病患者沙门菌分离株MLST分型及流行特征研究

目的 掌握江西省食源性疾病患者沙门菌分离株优势ST（MLST）型及其时空分布特征、流行趋势，分析血清型与ST型的对应关系。方法 以分离自2014—2018年江西省食源性疾病患者的313株沙门菌为研究对象，采用多位点序列分型（MLST）技术对菌株进行基因分型，探讨ST型别的时空分布特征及其与血清型的对应关系。结果 313株沙门菌共分为39种ST型，占比最高的是ST34（32.59%），其次是ST11（15.97%）、ST19（11.50%）。每年的优势ST型基本为ST34、ST11、ST19，地区间ST型分布存在差异：上饶市ST型种类最多（20种），其次是抚州市（15种）、景德镇市（14种）；南昌市优势ST型别为ST11、新余和鹰潭市优势ST型为ST19，而其他地市的优势ST型均为ST34。313株沙门菌共分为30个血清型，优势血清型为4，［5］，12：i：-（30.35%）、肠炎沙门菌（15.97%）、鼠伤寒沙门菌（14.06%）。结论 江西省食源性疾病患者沙门菌分离株的ST型别较多，年度流行ST型以ST34、ST11、ST19为主。这三种优势ST型在江西省不同地区间均有分布，但ST型在时空分布上也存在地区差异。     

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。     

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。     

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。     

2017—2020年江苏省无锡市沙门菌的血清型与耐药性研究

目的 分析2017—2020年江苏省无锡市沙门菌报告病例的血清型特点和抗生素耐药性流行特征及变化趋势。方法 收集分离自 2017—2020年无锡市食源性疾病哨点监测医院腹泻病例（住院和门诊患者）标本中的216株沙门菌菌株,采用玻片凝集法对216株菌进行血清型鉴定及分析,并采用微量肉汤稀释法检测沙门菌对13种抗生素的药物敏感性。结果 216株沙门菌分为42种血清型,优势血清型分别为肠炎沙门菌28.70%（62/216）占比,鼠伤寒沙门菌26.39%（57/216）。耐药性分析结果显示,216株沙门菌对美洛培南、阿米卡星、阿奇霉素和头孢他啶高度敏感,高敏菌株占比均高于90%;所有沙门菌对氨苄西林的耐药率最高,达到68.06%,对美洛培南的耐药率最低,仅0.46%;沙门菌在2017—2020年对氨苄西林的耐药率呈逐年增高的趋势,且每年沙门菌分离株对氨苄西林耐药性最高;共130株菌株产生了多重耐药性（60.19%）,耐药菌株数最多的耐药谱为AMP-TET-STR,占比5.56%（12/216）,优势耐药谱不明显。结论 无锡市沙门菌的流行血清型以肠炎沙门菌和鼠伤寒沙门菌为主,且沙门菌耐药性形势严峻,应该尽快建立高效的管控机制, 加强药敏监测, 优化治疗方案, 避免抗生素滥用。     

重庆市2019—2020年食源性疾病主动监测病原学及饮食史分析

目的 了解重庆市食源性疾病病原体感染情况,分析可疑饮食及其来源,为食源性疾病防控策略提供参考。方法 收集重庆市27家哨点医院2019—2020年就诊的食源性疾病病例信息。采集就诊病例的粪便或肛拭标本,检测其沙门菌、副溶血性弧菌、志贺菌、致泻大肠埃希氏菌及诺如病毒情况。结果 共监测4 294例腹泻病例,病原体总检出率为12.09%（519/4 294）,其中诺如病毒5.33%、沙门菌4.66%、致泻大肠埃希氏菌1.96%、志贺菌0.12%、副溶血性弧菌0.02%。二、三季度的病原体检出率较高（18.50%,13.00%）,呈现较明显的夏秋季高峰。不同年龄组病原体检出率以0~1岁组最高,为19.19%（71/370）。4 294例病例中有4 289例提供了可疑饮食信息,其中肉与肉制品占19.26%（846/4 289）、粮食类及其制品占17.65%（757/4 289）;食物加工方式中家庭自制占58.27%（2 502/4 289）,餐饮服务业占30.64%（1 314/4 289）;食物来源中家庭占55.42%（2 377/4 289）、餐饮店占12.17%（522/4 289）、零售店占10.91%（468/4 289）。结论 在监测的病原体中,诺如病毒和沙门菌是重庆市食源性疾病的主要病原体,可疑饮食以家庭自制食品占比较大。建议在食源性疾病高发的夏秋季加强食品安全监管,重点关注0~1岁婴儿期人群,开展家庭的食品卫生安全知识宣教。加强食源性疾病主动监测,为开展有效防控提供技术支持。     

一起肠炎沙门菌引起的校园食源性疾病暴发事件调查溯源分析

目的 调查一起肠炎沙门菌引起的学校食源性疾病暴发事件,并对危险因素开展分析溯源,为预防类似事件的发生提供科学依据。方法 运用描述性流行病学方法分析事件的流行病学特征;运用病例对照研究调查可疑食物;通过环境卫生学方法调查追溯食品污染的过程;对病例、食物、环境样品进行病原菌分离、血清分型和脉冲场凝胶电泳（PFGE）检测。结果 本起暴发事件共报告病例71例,流行曲线符合持续同源暴发模式的特点。病例对照、环境卫生调查和病因溯源研究提示学校超市售卖的三明治是引起本次事件的危险食品（OR=302.09,95%CI=75.18~1 213.97）。采集的病例、食品、环境样品中有8份（12.70%,8/63）检出了肠炎沙门菌,分离菌株的PFGE图谱条带完全一致,证实了学校超市出售的三明治使用的沙拉酱在制作过程中被肠炎沙门菌污染,是导致这次食源性疾病暴发的原因。结论 本次事件是由肠炎沙门菌污染食品引起的食源性疾病暴发,可疑食品为被自制沙拉酱污染的三明治。建议禁止各类未经充分热处理的含生鲜鸡蛋成分的食品进入学校,相关行政部门应加强对该类食品的卫生监督。     

赣州市食源性腹泻患者分离沙门菌耐药性和分子分型特征研究

目的 了解赣州市食源性沙门菌耐药性和分子分型特征,建立赣州市食源性沙门菌耐药性和分子指纹图谱数据库,为临床合理用药和食源性沙门菌病的暴发溯源提供科学依据。方法 对赣州市2020—2022年食源性疾病主动监测中分离的136株沙门菌进行血清分型、药物敏感性试验、全基因组测序（WGS）和脉冲场凝胶电泳（PFGE）,并进行耐药基因注释和图谱聚类分析。结果 赣州市食源性沙门菌对STR耐药率最高（83.09%）,其次为TET（78.68%）和AMP（76.47%）;多重耐药菌株占76.47%,耐药谱型广泛,主要流行耐药谱型为AMP-TET-CHL-STR-SXT;WGS预测出7种类别共61种耐药基因,以氨基糖苷类耐药基因携带率（99.19%）最高,大环内酯类（8.87%）最低;136株沙门菌以鼠伤寒变种和鼠伤寒为优势血清型,经PFGE分子分型分为98种带型。结论 赣州市食源性沙门菌耐药状况严重,耐药基因携带率高且基因型多样,PFGE分子型别呈多态性,优势血清型别可能引起暴发流行,应加强监测和研究。     

频率匹配Hald模型在非伤寒沙门菌感染散发病例归因中的应用研究

目的 探索频率匹配模型在食源性致病菌食物归因中的应用，识别导致我国某省2016—2020年非伤寒沙门菌（NTS）感染散发病例的主要食物来源，为精准防控提供科学依据。方法 通过食源性疾病监测报告系统和食品污染物风险监测系统收集并整理患者和食物来源NTS血清型数据，采用Hald模型，纳入病例和食物共有的血清型开展归因分析。结果 NTS感染散发病例归因于畜肉的比例最高，为35.67%，其中猪肉的贡献比例高达22.37%；其次是蛋及蛋制品，归因比例为33.83%；归因于禽肉和水产动物的比例分别是19.28%和11.22%。通过归因识别发现单相鼠伤寒可能是导致该省NTS病例的优势血清型。结论 采用Hald模型获得猪肉是某省NTS感染散发病例的重要病因食品，为该省NTS的污染控制提供了线索，为应用频率匹配模型解决散发病例归因问题提供了范式，该模型可拓展应用于对其他省份感染散发病例的归因研究。     

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.