秦皇岛市一起野生蘑菇中毒事件的调查和确证

目的 调查分析秦皇岛市一起食用野生蘑菇中毒事件,鉴定毒蘑菇种类,总结调查处置经验,提出防控措施,为野生蘑菇中毒患者的救治和预防提供借鉴。方法 运用现场流行病学调查、形态学鉴定和蘑菇毒素检测方法对中毒事件进行综合判断分析。结果 秦皇岛市4名村民食用自采野生蘑菇后全部出现恶心、腹痛、腹泻、多汗、寒颤等症状。在医院接受催吐、洗胃、给予阿托品及其他对症治疗,患者预后良好。经形态学鉴定和毒素检测后判定为一起由食用丝盖伞属蘑菇引起的食物中毒。结论 这是河北省首次报道由丝盖伞属蘑菇引起的中毒事件,中毒原因系受网络误导,食品安全防范意识差导致的误食。因此应加强食品安全宣传教育,提升民众防范意识,预防采食野生蘑菇中毒。     

超高效液相色谱串联四级杆飞行时间质谱法检测毒蘑菇中4种常见毒素含量

目的 建立超高效液相色谱串联四级杆飞行时间质谱法快速检测毒蘑菇中毒蝇碱、毒蝇母、鹅膏蕈氨酸、脱磷酸裸盖菇素4种强毒性毒素含量的分析方法。方法 新鲜蘑菇样品经过一系列的前处理后, 待测样品经ACQUITY UPLC BEH Amide色谱柱(100 mm×2.1 mm, 1.7 μm)分离, 以甲醇-5 mmol/L乙酸铵水(20:80, V:V)为流动相进行梯度洗脱, 流速为0.3 mL/min, 柱温为26 ℃, 外标法定量检测。结果 在一定浓度范围内, 4种毒素的线性关系良好, 相关系数大于0.999, 3水平加标回收率为86.7%~110.6%, 相对标准偏差为3.5%~6.2%, 检出限为0.0002~5.0 μg/mL。结论 该方法灵敏、准确、特异性好, 适用于蘑菇中毒蝇碱、毒蝇母、鹅膏蕈氨酸、脱磷酸裸盖菇素的检测。     

应用rDNA-内转录间隔区分子条形码技术调查福建省亚稀褶黑菇中毒事件

目的调查福建省南平地区3个市县的3起野生菌食物中毒事件,为今后野生菌中毒调查和处置积累经验,减少中毒事件的发生。方法通过查阅中毒患者的临床救治资料,前往中毒事件发生地采集引起中毒的可疑蘑菇样品,并采用rDNA-内转录间隔区(rDNA-ITS)分子条形码鉴定技术进行种属鉴别。结果中毒流行病学特征、中毒患者临床特征、生化指标变化和分子生物学鉴定的结果表明,2017年8月的2起食物中毒事件均由亚稀褶黑菇(Russula subnigricans Hongo)导致;根据中毒患者临床特征,另一起中毒事件亦被推断为由亚稀褶黑菇引起;3起中毒事件中,蘑菇食用者为21人,发病17人,罹患率为81.0%,其中3人死亡,病死率为17.6%(3/17)。结论首次在福建省通过分子生物学手段鉴别出由亚稀褶黑菇引起的食物中毒事件;亚稀褶黑菇广泛分布于福建山区,易被误采误食而引起中毒事件,且病死率高。     

一起误食野蘑菇中毒事件的调查分析

目的 调查分析一起野蘑菇中毒事件,为毒蘑菇中毒的防控提供参考。方法 通过流行病学调查、食品卫生学调查、实验室检测、动物试验,查找本次食物中毒原因。结果 搜索发现同一家庭中毒患者4名,罹患率80.0%,临床表现为恶心、呕吐、腹痛、腹泻等胃肠道症状,平均潜伏期3h,食用野蘑菇与发病之间存在剂量-反应关系。采集剩余野蘑菇7个及患者指认的草坪现场同一种类野蘑菇4个,经形态学鉴定为大青褶伞,动物试验显示该野蘑菇有消化系统毒性。结论 本次中毒事件为一起误食有毒大青褶伞引起的食物中毒事件。     

林下大型野生菌的分离培养研究

对沈阳林下大型野生菌类调查和分离表明,沈阳辉山针阔混交林下,8月中旬至9月底,以马勃、乳牛肝居多.8月下旬至9月底,乳牛肝和红菇是盛产期.10月铆钉菇较多.木腐生菌黄伞和土腐生菌如环绣伞、麻脸菇、淡黄褐粉褶菌等都极易分离,成功率达80%以上.疑似菌根菌种荷叶离褶伞、灰紫香蘑、马勃、须腹菌、桩菇、环柄菇等都能在供试种培养基上生长,燕麦、玉米和西瓜培养基是荷叶离褶伞分离的最佳培养基.菌根菌血红铆钉菇,在以菇类子实体和玉米为主要成分的培养基上分离成达6.7%;其他菌根菌种如金乳牛肝菌、黄白粘盖牛肝菌、厚环乳牛肝菌、褐环乳牛肝菌等分离成功率为0～10%.红菇和乳菇,是极难分离的菌种,即使在组织块上已萌动,转接后仍不生长.子实体含水量饱和的分离未成功.     

江西省铅山县一起蘑菇中毒事件的调查与鉴定

目的调查江西省铅山县一起蘑菇中毒事件并对引起中毒的毒蘑菇进行鉴定。方法收集事件病例资料,开展流行病学调查,对蘑菇样品进行外观形态学、分子生物学鉴定。结果流行病学调查结果显示患者均食用了自行采摘的蘑菇,潜伏期约为4 h,出现呕吐、胃肠道不适等中毒症状,给予补液、激素、保肝等护胃解毒支持疗法进行治疗,3 d后全部痊愈出院。分子生物学方法鉴定为疑似大青褶伞。结论此次事件因误食可疑大青褶伞野生蘑菇而引起急性中毒,结合流行病学、分子生物学等方法可以较好地鉴定毒蘑菇种类。     

一起条盖盔孢伞中毒事件调查

目的对2019年成都市发生的一起毒蘑菇中毒事件进行调查分析,明确中毒原因,总结调查处置经验。方法通过流行病学调查,毒蘑菇样品的形态学鉴定、分子生物学鉴定和毒素检测,综合判断本起食物中毒的原因。结果本起毒蘑菇中毒事件暴露人数3人,发病3人,死亡1人,早期临床表现为腹痛、呕吐、腹泻等,后逐渐出现肝功能损害。毒蘑菇样品经形态学和分子生物学鉴定为条盖盔孢伞。样品中检出α-鹅膏毒肽、β-鹅膏毒肽和γ-鹅膏毒肽。结论本起食物中毒是由误食毒蘑菇条盖盔孢伞引起。为防范类似事件再次发生,应做好大众健康教育,加强食品安全监管及食源性疾病监测力度,并提高医疗机构的诊疗能力。     

液相色谱-串联质谱法检测一起误食曼陀罗引起的食物中毒物质

目的 对一起疑似食用野菜中毒事件进行实验室检测分析，为中毒事件的处置和患者救治提供科学依据。方法 利用液相色谱-三重四级杆串联质谱（LC-MS/MS）对采集的样本进行阿托品、东莨菪碱、山莨菪碱定性和定量检测。对现场采集的可疑植物进行形态学鉴定，结合流行病学调查确定中毒因子。结果 从中毒当日患者食用的野菜饼和医院提供的生物样本中检出阿托品、东莨菪碱、山莨菪碱等莨菪烷类生物碱，在现场采集到的有毒植物经形态学鉴定为曼陀罗（Datura stramonium L.），患者临床症状及潜伏期与曼陀罗中毒表现相类似。结论 本次事件是由误食曼陀罗引起的食物中毒，实验室检测结果为中毒事件快速、准确的确证起到了关键作用。     

一起误食野生植物常山中毒事件的调查分析

目的 通过调查处置一起误食野生植物常山致常山碱中毒的事件,为常山碱中毒临床救治和预防提供参考依据。方法 通过流行病学调查、卫生学调查、实验室检测、形态学和分子生物学鉴定确定中毒原因,结合临床症状、治疗用药和患者治愈情况总结中毒治疗经验。结果 根据常山的植物学鉴定和分子生物学鉴定结果,该起中毒事件的标本鉴定为云南常山,中毒物质为常山碱,食用人群罹患率100%,中毒临床表现为恶心、呕吐、腹泻和里急后重等胃肠道症状,给予补液、护胃、补钾及广谱解毒治疗后24 h内痊愈,无迟发型其他症状。结论 本次事件为一起误食新鲜云南常山致常山碱中毒引起的中毒事件,此前国内未见直接食用新鲜云南常山中毒事件报告,为类似中毒事件的预防、临床救治提供重要的参考价值。     

不同保鲜方法对白玉菇保鲜品质及货架期的影响

为探讨不同保鲜方法对白玉菇保鲜品质及货架期的影响,设置不同浓度乙醇熏蒸、不同温度热处理两种保鲜方法,对保鲜过程中白玉菇的呼吸强度、褐变度、失重率、细胞渗透率和感官评价等指标进行检测。结果表明,乙醇熏蒸法能显著抑制白玉菇的呼吸强度、褐变度,降低失重率和细胞渗透率,较好地保持感官品质;其中,450μL/L乙醇熏蒸法处理的白玉菇保鲜品质最优,能延长货架期至14天。与对照组相比,40℃热处理能有效抑制白玉菇的褐变、降低细胞渗透率,保鲜品质相对较好,但不能延长货架期。     

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.     

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.     

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.     

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.     

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.     

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.     

Assessment of the microbiological safety of salad vegetables and sauces from kebab take-away restaurants in the United Kingdom

The purpose of this study was to establish the microbiological safety of salad vegetables and sauces served in kebab take-away restaurants. Comparison with published microbiological guidelines revealed that 4.7% of 1213 salad vegetable samples were of unsatisfactory microbiological quality due to Escherichia coli and/or Staphylococcus aureus levels at ≥10² cfu g⁻¹. Another 0.3% of salad samples were of unacceptable quality due to S. aureus at ≥10⁴ cfu g⁻¹ (2 samples) or the presence of Salmonella Kentucky (1 sample). Cucumber was the most contaminated salad vegetable with regards to unsatisfactory levels of E. coli (6.0%) or S. aureus (4.5%). Five percent of 1208 sauce samples were of unsatisfactory microbiological quality due to E. coli, S. aureus at ≥10² cfu g⁻¹ and/or Bacillus cereus and other Bacillus spp. at ≥10⁴ cfu g⁻¹. A further 0.6% of sauce samples were of unacceptable quality due to Bacillus spp. (Bacillus subtilis, Bacillus pumilus, Bacillus licheniformis) at ≥10⁵ cfu g⁻¹ or the presence of Salmonella Agbeni (1 sample). More samples of chilli sauce (8.7%) were of unsatisfactory or unacceptable microbiological quality than any other sauce types. The results emphasize the need for good hygiene practices in kebab take-away restaurants handling these types of ready-to-eat products.