麻痹性贝毒在广州市售经济贝类中污染状况分析

目的通过对广州市黄沙海产品批发市场7种经济贝类为期一年的麻痹性贝毒(PSP)污染状况的调查分析,了解海产品食用的安全性。方法毒性测定按照AOAC小白鼠法进行,成份分析利用高效液相色谱(HPLC),安全性评价采用联合国粮农组织(FAO)及我国渔政渔港监督管理局制定的贝类安全食用标准(4MUg肉)。结果在调查的84份贝样中,染毒贝整体毒力(消化腺与肉的加权平均毒力)低于4MUg肉,毒素最高含量仅为184MUg肉,所有贝类均在安全食用范围之内。染毒贝类主要为栉孔扇贝(ChlamysMimachlamysnobilis)和嵌条扇贝(Pectenalbicans)。毒素在2个种9份样品的消化腺中检出,某些样品肌肉组织出现小白鼠毒性反应。一份样品消化腺中毒素含量高达1452MUg,高效液相色谱(HPLC)分析表明,该样品毒素成份主要为B1、GTX23、GTX14及C类。结论广州市市售鲜贝PSP含量和检出率整体水平均较低;贝中消化腺毒素含量及检出率明显高于肌肉,个别腺体毒素含量超出标准。毒素分布存在季节性差异,春季毒素比较强,夏秋季检出率高。因此有针对性的加强贝毒监测非常必要。     

中国沿海的贝毒问题研究

我国对贝毒的调查研究工作目前正在开始，除了已查明江瑶具有内源性贝毒之外，主要的研究工作集中在赤潮产生的麻痹性贝毒（ＰＳＰ）上面，ＰＳＰ中毒案例主要发生在中国南方的浙江、福建、广东及台湾等地，其中有一些案例是致命性的。科研人员研究了广东省各种贝类中ＰＳＰ的含量，组织中分布及季节变化的情况，对其组份进行分析发现主要成份为ＳＴＸ，ｎｅｏＳＴＸ及ＧＴＸ１～４等。在我国沿海已发现了三种产生ＰＳＰ的毒藻，其中的Ａｌｅｘａｎｄｒｉｕｍｔａｍａｒｅｎｓｅ已分离出孢子并培养出单株克隆体供研究用，值得注意的是，我国沿海还发现过产生腹泻性贝毒，神经性贝毒及失忆性贝毒等毒源藻类，应提高警惕其形成“赤潮”，并在贝体内大量积累的可能性     

Diarrhetic Shellfish Poisoning,Washington, USA, 2011

Diarrhetic shellfish poisoning is a gastrointestinal illness caused by consumption of bivalves contaminated with dinophysistoxins. We report an illness cluster in the United States in which toxins were confirmed in shellfish from a commercial harvest area, leading to product recall. Ongoing surveillance is needed to prevent similar illness outbreaks.     

宁波市有毒织纹螺地域分布分析

目的了解宁波市有毒织纹螺的分布。分析各栖息地有毒织纹螺的毒性变化，为控制织纹螺中毒提供依据。方法采用美国分析化学家学会（AOAC）和中国进出口检验检疫（CIQ）的小鼠生物测试法，以美国食品药物管理局（FDA）的贝类麻痹性毒素（PSP）标准，判定本地织纹螺毒性的强弱，按年观察结果。结果1986～2003年，宁波市127份被检织纹螺中毒素平均含量最高的年份为1991年，达11900MU／100g螺肉，最低年份为1988年，其毒素含量也达403MU／100gN肉，其他年份的毒性波动在一定范围内。不同栖息地毒螺检出率镇海区为31．43％，北仑区为39．29％，宁海县为73．08％，奉化市为25．00％，经统计学处理差异有统计学意义（P〈0．01）；除宁海外，其余3个县（市、区）毒螺检出率差异无统计学意义（P〉0．05）。从新增织纹螺栖息地象山采集的30份织纹螺样品，毒素测定值均≤400MU／100g肉，未检出毒螺。结论宁波市各栖息地的织纹螺带毒严重，是一种引起织纹螺中毒的原因食物。各栖息地织纹螺毒性存在差异，以宁海县的织纹螺带毒最普遍。毒螺的分布和毒性的强弱与地域相关。织纹螺毒素的毒性可消长，但无规律性。     

An outbreak of E. coli O157:H7 hemorrhagic colitis associated with unpasteurized gouda cheese

BACKGROUND: A cluster of E. coli O157:H7 hemorrhagic colitis was identified in metro Edmonton, Alberta through notifiable disease surveillance in late 2002. METHODS: Environmental health officers collected food histories and clinical information from cases in the cluster. The provincial public health laboratory conducted pulsed field gel electrophoresis (PFGE) analysis on E. coli O157:H7 isolates from cluster cases. Public health and food regulatory agencies conducted an investigation when a food source (unpasteurized gouda cheese) was implicated. RESULTS: PFGE analysis revealed an "outbreak" profile in 13 cases. Onset dates for the outbreak cases ranged between October 2002 and February 2003. Two cases, aged 22 months and 4 years, developed hemolytic uremic syndrome as a result of their infection. Consumption of unpasteurized gouda cheese produced at a local dairy farm was reported by 12 of 13 outbreak cases in the 2 to 8 days prior to illness. E. coli O157:H7 was isolated from 2 of 26 cheese samples manufactured by the implicated producer. The cheese isolates had indistinguishable PFGE profiles as compared with outbreak case isolates. Implicated cheese was found to be contaminated with E. coli O157:H7 104 days after production, despite having met regulated microbiological and aging requirements. CONCLUSION: To our knowledge, this is the first confirmed outbreak of E. coli O157:H7 infection in Canada associated with raw milk hard cheese. A review of federal legislation vis-à-vis raw milk hard cheese may be in order.     

Paralytic shellfish poisoning --- southeast Alaska, May--June 2011

On June 6, 2011, the Section of Epidemiology (SOE) of the Alaska Division of Public Health was notified of a case of paralytic shellfish poisoning (PSP) in southeast Alaska. In collaboration with local partners, SOE investigated and identified a total of eight confirmed and 13 probable PSP cases that occurred during May--June 2011. Warnings to avoid noncommercially harvested shellfish were broadcast on local radio and television and displayed at beaches and in post offices, government offices, and businesses throughout the region. Commercially harvested shellfish, which are tested for the presence of PSP-causing toxins, were safe. Because the risk for PSP is unpredictable, persons who consume noncommercially harvested Alaskan shellfish should know that they are at risk for PSP, and suspected cases should be reported promptly to SOE to initiate control measures in the affected area.     

广州市售贝类麻痹性贝毒和腹泻性贝毒污染状况分析

目的对广州市售双壳经济贝类麻痹性贝毒(PSP)和腹泻性贝毒(DSP)污染状况进行为期一年的抽样调查,了解其食用安全性。方法采用AOAC推荐的小鼠生物检测法进行PSP和DSP的毒力测定,采用HPLC进行PSP成分分析,根据FAO、日本和欧盟水产食品卫生要求及我国渔政渔港监督管理局制订的贝类安全食用标准对贝类水产品的食用安全性进行评价。结果在所调查的7种贝类中,有2种染有PSP,毒素含量在安全食用范围内,毒力大小随季节而变化,春冬两季含量相对较高;7种贝类中有6种共计36个样品染有DSP,有10个样品毒素含量超出安全食用标准,春冬两季染毒率较高。结论广州市售贝类PSP含量和检出率整体水平较低;DSP检出率稍高,毒素含量也较高,应引起有关部门的关注,加强DSP监测工作。     

Epidemiologic application of pulsed-field gel electrophoresis to an outbreak of Campylobacter jejuni in an Austrian youth centre

We report the first documented Campylobacter jejuni outbreak in an Austrian youth centre. Sixty-four children were involved of which 38 showed classical signs of campylobacter gastroenteritis. Since unpasteurized milk distributed by a local dairy was suspected to be the source of infection, stool samples were collected from 20 cows providing the milk. Five of the cows tested positive for C. jejuni. These isolates together with 37 clinical samples were compared by pulsed-field-gel electrophoresis (PFGE). The PFGE patterns, using the restriction endonucleases SmaI and SalI, were identical for the human and bovine isolates.This finding confirmed that the outbreak was caused by the consumption of unpasteurized milk contaminated with C. jejuni.     

Paralytic shellfish poisoning toxin profiles in green mussels from Trinidad and Venezuela

Paralytic shellfish poisoning (PSP) toxins were determined in green mussels (Perna viridis) from the Gulf of Paria between Trinidad and Venezuela, as well as from the northern coast of Venezuela. Aqueous extracts of samples were purified by passage through SPE C-18 and carboxylic columns, and oxidized by periodate and peroxide reagents, before analysis by LC with fluorescence detection. Spike and recovery of mixed toxins from uncontaminated mussel tissues, with % recoveries from 83 to 103, validated the method of analysis. Saxitoxin (STX), gonyautoxins (GTX), their analogs, and C toxins were identified in mussels from both countries. In the Gulf of Paria, PSP toxin profiles in mussels from the north were similar to each other, as were those from the south. However, the toxin profiles and concentrations varied widely among geographic areas, with GTX analogs and C1,2 toxins predominating. The highest total PSP concentrations (468 μg/100 g), as well as the largest number of individual toxins identified (7 of 8), were found at Playa Patilla on the northern coast of Venezuela, followed by Chaguaramas (244 μg/100 g; 6 of 8) and Güiria (154 μg/100 g; 5 of 8) in the northern Gulf of Paria in Trinidad. While the calculated STX equivalents in each sample were below the maximum permissible level (80 μg/100 g) permitted by Venezuela and other countries, its very detection prohibits their consumption in Trinidad under existing legislation.     

双壳贝类麻痹性贝毒抗性机制的研究

麻痹性贝毒(PSP)是一类神经肌肉麻痹剂,可以阻断电压门控钠离子通道,造成神经系统传输障碍而产生麻痹作用。某些双贝壳类对PSP毒素具有耐受性和抗性,其抗性机制可能与代谢速率、生物转化和钠通道突变等有关,其中钠通道突变是双壳贝类对PSP毒素产生抗性的最重要的分子机制。     

麻痹性贝类毒素细胞检测法的建立

目的:麻痹性贝类毒素的N-2a细胞检测方法的建立并确定可能的检测限值。方法:使用不同浓度毒素标准品结合藜芦定和乌本苷共同作用对数生长期的N-2a细胞,通过cck-8试剂盒检测细胞毒性,确立细胞检测方法的检出限及比较各毒素作用大小,并同步利用小鼠生物法进行验证,通过精确记录小鼠死亡时间,比较各毒素的毒作用大小。结果:麻痹性贝类毒素能明显降低藜芦定和乌本苷的细胞毒性,且具有剂量-反应关系,通过比较得出毒素各成分毒性大小为:neoSTX>STX>dcSTX>GTX1,4>GTX2,3>dcGTX2,3;小鼠生物法的毒作用平均死亡时间为:neoSTX组(6.5 min),GTX1,4组(8.0 min),STX组(9.0 min),dcSTX组(15 min);GTX2,3组和dcGTX2,3组未见动物死亡。结论:细胞检测与小鼠生物法具有较好的一致性,表明所建立的细胞检测法可行,且细胞毒性试验检测方法具有较高的灵敏度,最低检出限值可达到10-9mol/L剂量水平,其中浓度在10-6~10-8mol/L间具有较好的线性。     

Distribution of Polychlorinated Naphthalene Congeners in Environmental and Source-Related Samples

Polychlorinated naphthalene (CN) congener profiles in environmental and source related samples were compared graphically and by principal component analysis. Samples investigated included biological, sediment, water, and air samples, technical polychlorinated biphenyl (PCB) and polychlorinated naphthalene (PCN) formulations, as well as municipal waste incineration (MWI) fly ash and graphite electrode sludge. Biological samples showed a preferential enrichment of planar, 1,3,5,7-substituted tetra-, penta-, and hexachlorinated congeners and most of these samples showed profiles that displayed some similarity to those found in the technical PCB formulations. Sediment samples representing diffuse pollution, i.e., sediment samples from remote sites, showed an elevated abundance of the planar hexa- and heptaCN congeners (1,2,3,4,6,7-/1,2,3,5,6,7- and 1,2,3,4,5,6,7-). The CN congener profile found in these sediment samples and the two air samples were more similar to the technical PCB formulations than to the investigated MWI and graphite sludge samples. Samples from three PCB contaminated lakes displayed similar congener profiles as Aroclor 1242, 1254 and Clophen A40. Two sediment samples and a pike sample collected from the vicinity of a chloroalkali plant showed profiles that were closely related to the investigated graphite electrode sludge sample. None of the environmental samples displayed profiles similar to low or medium chlorinated technical PCN (Halowax 1099, 1013, and 1014). Received: 29 June 1995/Revised: 16 May 1996     

从暴发腹泻的贻贝中同时检出腹泻性贝类毒素和扇贝毒素

目的:2011年5月25日-5月27日,我市苍南县暴发了57例因食用贻贝引起的腹泻性贝类毒素(DSP)中毒事件,采集了19份样品进行检测。方法:采用超高效液相色谱-串联质谱方法对贻贝中5种脂溶性贝类毒素进行检测,根据欧盟贝类毒素的限量值进行评价。结果:15份样品检出大田软海绵酸(OA)、鳍藻毒素-1(DTX-1)和7-epi-pectenotoxin-2 seco acid(7-epi-PTX-2sa),16份检出pectenotoxin-2seco acid(PTX-2sa),7份检出pectenotoxin-2(PTX-2)。其中4份样品中游离OA和DTX-1含量超出欧盟限量值3倍多,它们的总OA约超出9倍。其余均低于欧盟限量值。首次在我国贝类中检出了PTX-2sa和7-epi-PTX-2sa。结论:鉴于部分贻贝样品DSP超标,今后应加强贝类上市前的监测工作。     

一起赤潮后海产品麻痹性贝类毒素衰减结果分析

目的 以2017年漳州沿海一起赤潮引起的麻痹性贝类毒素(paralytic shellfish poisoning,PSP)中毒事件为研究起点,研究贝类海产品中的PSP在自然条件下的衰减情况。方法 在漳浦佛昙和龙海港尾海域采集牡蛎和贻贝进行PSP检测。结果 2017年6月8日相关海域海产品最大毒素总毒力为21 056.7 μg/kg,2017年6月26日海产品PSP总毒力值衰减86%以上,2017年7月20日海产品PSP总毒力值衰减97%以上,2018年12月所有海产品中PSP均未检出。结论 本次赤潮发生后,漳浦佛昙和龙海港尾两个海域贝类海产品约需45天净化周期方可食用,相关海域约需18个月净化至贝类毒素完全消失。     

Waterborne outbreak of Norwalk-like virus gastroenteritis at a tourist resort,Italy

In July 2000, an outbreak of gastroenteritis occurred at a tourist resort in the Gulf of Taranto in southern Italy. Illness in 344 people, 69 of whom were staff members, met the case definition. Norwalk-like virus (NLV) was found in 22 of 28 stool specimens tested. The source of illness was likely contaminated drinking water, as environmental inspection identified a breakdown in the resort water system and tap water samples were contaminated with fecal bacteria. Attack rates were increased (51.4%) in staff members involved in water sports. Relative risks were significant only for exposure to beach showers and consuming drinks with ice. Although Italy has no surveillance system for nonbacterial gastroenteritis, no outbreak caused by NLV has been described previously in the country.     

一起学校细菌性痢疾暴发疫情的病原追溯 和流行病学特征分析

摘要:目的　对学校发生的一起细菌性痢疾暴发疫情进行调查,并采用脉冲凝胶电泳（PFGE）方法对菌株进行同源性分析,为查找传染源、切断传播途径,提供参考依据。方法　开展现场流行病学调查,采用描述流行病学的方法对暴发原因进行分析,同时采集患者粪便、水样进行细菌学培养,运用PFGE对分离的菌株进行同源性分析。结果　此次暴发疫情的调查共发现病例60例,罹患率为10.12%,发病人群均为小学学生;从53例患者的粪便中共检出30例痢疾阳性病例,且菌群均为宋内志贺菌;水样检测发现2号水井及其旁边的水塘存在宋内志贺菌;对4份病例的粪便、2份水样进行PFGE分析,其结果显示,6份样本所检出菌株的电泳带型完全相同。结论　该事件是一起因饮用宋内志贺菌污染的水源而导致的细菌性痢疾暴发疫情。     

A statewide outbreak of Escherichia coli O157:H7 infections in Washington State

In November 1986, a statewide outbreak of Escherichia coli O157:H7 infections in Washington State was identified after a physician in an eastern Washington community hospitalized three patients with hemorrhagic colitis which progressed to thrombotic thrombocytopenic purpura. Epidemiologic investigation identified 37 cases in this community and linked the illnesses to a local restaurant which had served ground beef that was the suspected initial vehicle of transmission. The plasmid profile and toxin production pattern (Shiga-like toxin II alone) of the outbreak strain provided a unique strain marker. E. coli O157:H7 infections caused by this strain were simultaneously seen in other parts of the state among nursing home residents and in patients with the hemolytic-uremic syndrome, and an increase in sporadic cases of hemorrhagic colitis was noted at a Seattle health maintenance organization. It is suspected that a contaminated product, probably ground beef distributed statewide, was the common source. Tracing of this meat led to farms where rectal swabs from six (1%) of 539 cattle tested yielded E. coli O157:H7, although the plasmids and toxin production patterns of these isolates differed from the human outbreak strain. Introduction of a single strain of E. coli O157:H7 has the potential to cause widespread concurrent outbreaks. Such outbreaks are likely to escape recognition until heightened screening and surveillance for E. coli O157:H7 is established.     

ELISA快速测定带子中麻痹性贝类毒素含量

目的 分析测定导致中毒的带子及珠海市售的带子中麻痹性贝类毒素(PSP)含量.方法 依据SN/T1773-2006,采用美国Abraxiskits公司生产的SAXITOXIN (PSP) ELISA KIT (96T)试剂盒,测定食物中毒客户留样及市售的带子样品中麻痹性贝类毒素含量,并进行方法检出限、相对标准偏差(RSD)测定,以确保检测结果的有效性.结果 6份带子样品(1份食物中毒客户留样,5份市场抽检),其中5份检出麻痹性贝类毒素,含量为9.1～59.9 μg/kg.方法检出限为5.0 μg/kg、RSD为12.9％.结论 所检6份带子样品中有5份检出含有麻痹性贝类毒素(PSP).所检样品PSP的含量与流行病学调查较吻合.     

Relationship between the contamination of gulls (Larus dominicanus) and oysters (Crassostrea gigas) with Salmonella serovar Typhimurium by PCR-RFLP

Shellfish can bioaccumulate in their tissues pathogenic contaminants present in water and they have been related with several outbreaks of food-borne diseases worldwide. With their increased population in urban areas, gulls have been reported as an important source of water environment contamination. During a 10-month period, water, gulls feces and oyster samples were collected in a shellfish harvesting site and analyzed for total and fecal coliform counts (water) and Salmonella presence (gull feces and oyster meat). Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to differentiate Salmonella species detected in gulls and oysters. Salmonella presence was detected in 3/10 of oyster samples and in 6/10 of gull feces samples by PCR. There was a relationship between Salmonella presence in oysters and fecal contamination in water. Restriction profiles of both gulls and oyster samples were similar to Salmonella Typhimurium profile by RFLP. These findings indicate strong evidence that gulls can contribute to Salmonella contamination of harvested oysters.     

Interpretation of band differences to distinguish strains of Serratia marcescens by pulsed-field gel electrophoresis of XbaI DNA digests

The number of band differences in DNA macrorestriction profiles required to distinguish unrelated strains from an index strain varies in an outbreak with the species and restriction enzyme used. In order to define this difference for epidemiological studies of Serratia marcescens, we produced DNA fingerprints from 57 isolates of the organism using the restriction enzyme XbaI and pulsed-field gel electrophoresis (PFGE). The isolates were selected on the basis of their epidemiology, serotype and phage-typing patterns to include 28 unrelated strains and 29 representatives from 2 distinct outbreaks. One of the outbreaks was prolonged. lasting for several years. Electrophoretic profiles consisting of 20 or more clearly resolved bands were obtained for all isolates. Twenty-six of the unrelated strains had unique profiles with over 10 band differences from all other strains, while 27 of the outbreak representatives could be assigned to the appropriate outbreak with confidence. The majority of the outbreak isolates had none or 2 band differences from the index profile, although 3 isolates differed by 5-7 bands. The 2 exceptions among the unrelated strains differed by 4 bands, and 3 phage typing reactions, and were isolated from London and Berlin 3 years apart, while the 2 exceptions among the outbreak collection had clearly unique profiles with over 20 band differences from each other and the outbreak profiles. Cluster analysis using Dice coefficient and UPGMA gave cut-off values of 75-78% similarity overall for related isolates, while the closest similarity for unrelated strains was 70%. The results of this study together with those of the 6 previous reports of PFGE for S. marcescens (which used either enzymes XbaI or SpeI) confirm that this technique is of value for this species and that with XbaI at least, most epidemiologically related strains will only differ by 3-4 bands. However, on occasion up to 7 band differences can be found within an apparent outbreak, which may be suggestive of genetic drift.