北疆部分地区食源性大肠杆菌血清型、毒力基因及耐药基因的研究

目的研究北疆部分地区食源性大肠杆菌的优势血清型、毒力基因和耐药基因的相关性。方法采用玻片凝集法测定了大肠杆菌血清型分布,PCR方法调查11种耐药基因和9种毒力基因。结果血清试验,定型菌株26株,分别属于17种血清型,其中O1、O115为优势血清型;PCR结果表明,不含有所检测耐药基因的分离株占12.50%,至少含有2种以及以上的分离株占50.00%,分离株对blaOXA基因携带率高达57.14%;检出率较高的毒力基因为fimC(64.29%)和fimA(25.00%)。结论 O1、O115为主要的血清型,2种血清型菌株拥有的耐药基因谱和毒力基因谱不相同。     

Hyperendemicity associated with increased dengue burden

Over 105 million dengue infections are estimated to occur annually. Understanding the disease dynamics of dengue is often difficult due to multiple strains circulating within a population. Interactions between dengue serotype dynamics may result in complex cross-immunity dynamics at the population level and create difficulties in terms of formulating intervention strategies for the disease. In this study, a nationally representative 16-year time series with over 43 000 serotyped dengue infections was used to infer the long-run effects of between and within strain interactions and their impacts on past outbreaks. We used a novel identification strategy incorporating sign-identified Bayesian vector autoregressions, using structural impulse responses, historical decompositions and counterfactual analysis to conduct inference on dengue dynamics post-estimation. We found that on the population level: (i) across-serotype interactions on the population level were highly persistent, with a one time increase in any other serotype associated with long run decreases in the serotype of interest (range: 0.5–2.5 years) and (ii) over 38.7% of dengue cases of any serotype were associated with across-serotype interactions. The findings in this paper will substantially impact public health policy interventions with respect to dengue.     

肉猪养殖和屠宰环节沙门菌污染状况监测分析

目的 了解开封市肉猪养殖屠宰加工过程中沙门菌的污染状况.方法 采集不同来源的养殖场猪混合粪便、成年猪肛拭子、胴体涂抹物、肠系膜淋巴结样本,共187份,按照GB 4789.4-2010进行沙门菌的分离和鉴定.结果 猪混合粪便沙门菌检出率为4.5％,肛拭子沙门菌的检出率为16.4％,胴体涂抹物沙门菌检出率为34.5％,肠系膜淋巴结沙门菌检出率为27.3％.不同季节的检出率差异有统计学意义(P＜0.05).阳性分离株分布于沙门菌的5个群,共14个血清型,以阿贡纳沙门菌和德尔卑沙门菌为主.结论 屠宰环节是沙门菌交叉污染的关键点,应采取综合措施,有效控制猪肉沙门菌污染.     

Survival and High‐Hydrostatic Pressure Inactivation of Foodborne Pathogens in Salmorejo,a Traditional Ready‐to‐Eat Food

Salmorejo is a traditional tomato‐based creamy product. Because salmorejo is not heat‐processed, there is a risk of contamination with foodborne pathogens from raw materials. Even though bacterial growth in salmorejo is strongly inhibited because of its acidic pH (close to 3.9), the growth and survival of 3 foodborne pathogens in this food has not been studied before. In this study, 3 cocktails consisting of Escherichia coli O157, Salmonella enterica serovar Enteritidis, and Listeria monocytogenes strains were inoculated in freshly prepared salmorejo. The food was treated by high hydrostatic pressure (HHP) at 400, 500, or 600 MPa for 8 min, or left untreated, and stored at 4 °C for 30 d. Viable cell counts were determined on selective media and also by the triple‐layer agar method in order to detect sublethally injured cells. In control samples, L. monocytogenes viable cells decreased by 2.4 log cycles at day 7 and were undetectable by day 15. S. enterica cells decreased by 0.5 or 2.4 log cycles at days 7 and 15 respectively, but still were detectable at day 30. E. coli O157 cells survived much better in salmorejo, decreasing only by 1.5 log cycles at day 30. Treatments at pressures of 400 MPa or higher reduced viable counts of L. monocytogenes and S. enterica to undetectable levels. HHP treatments significantly (P < 0.05) reduced E. coli counts by approximately 5.2 to 5.4 log cycles, but also yielded surviving cells that apparently were sublethally injured. Only samples treated at 600 MPA for 8 min were devoid of detectable E. coli cells during storage.     

肉鸡饲养加工过程中沙门菌污染环节的探讨与分析

目的 探讨开封市肉鸡从孵化、养殖,到屠宰、加工、运输和销售各环节样品沙门菌污染状况.方法 采集2012年4个季度开封地区种鸡养殖场、肉鸡孵化场、养殖场、屠宰场和大型超市中土壤、饲料、鸡粪、鸡肉、屠宰工具、工人手等18个环节共802份样品.按照GB 4789.4-2010进行沙门菌鉴定和血清学分型,用SPSS 17.0软件对数据进行统计分析.结果 脱毛池水中沙门菌检出率最高为75％,其次成鸡粪便、鸡肉、刀具案板、肛拭子中沙门菌检出率分别为58.3％、49.4％、33.3％、5.6％,鸡胚和运输车辆中未检出沙门菌.本研究共检出6个血清型,以肠炎沙门菌和印第安纳沙门菌检出率最高;第二季度沙门菌菌型数最多.结论 鸡肉屠宰加工过程使沙门菌污染扩大,脱毛机及脱毛池水是沙门菌交叉污染的关键点,不同季节的检出率差异无统计学意义(P＞0.05).     

上海市水产品中副溶血性弧菌的分离、鉴定及毒力基因和血清型分布

为了了解上海市市售水产品中副溶血性弧菌(Vibrio parahaemoly ticus,Vp)污染状况和血清型,为防治Vp引起的食源性疾病提供依据。采用GB/T 4789.7-2008国标方法进行分离和生理生化鉴定,根据FDA推荐的引物对种特异性tlh基因和毒力基因(tdh,trh)进行PCR检测。从161份水产品中分离鉴定得到45株副溶血性弧菌,平均检出率为27.95%。通过PCR检测分离株的tdh和trh毒力基因发现,45株副溶血性弧菌均为trh阴性,7株为tdh阳性。45株副溶血性弧菌经血清凝集,结果共分出7个血清群,分别为O1群占2.2%(1/45),O3群占24.4%(11/45)、O4群占15.6%(7/45)、O5群占20.0%(9/45)、O9群占4.4%(2/45)、O10群占8.9%(4/45)、O11群占26.7%(12/45)。     

内蒙古呼和浩特地区鸡源沙门氏菌分离鉴定、血清学鉴定及耐药性研究

目的 了解内蒙古呼和浩特地区市售整鸡的沙门氏菌污染状况,为建立食物污染及公共卫生安全提供数据支持。方法 2011～2012年仍呼和浩特地区采集冷冻、冷藏和现宰杀整鸡样品,迚行沙门氏菌的定性检测、血清分型及耐药性研究。结果 不同状态整鸡样品的沙门氏菌携带率明显不同,冷藏整鸡沙门氏菌检出率显著高于冷冻和现宰杀整鸡。血清型主要为肠炎沙门氏菌(Salmonella enteritidis)。36株沙门氏菌均对头孢替坦、亚胺培南最为敏感,对氨苄西林、哌拉西林、呋喃妥因、氨苄西林/舒巴坦、头孢唑林等表现出不同程度的耐药性,多重耐药菌株中五耐最为严重(25%)。结论 内蒙古呼和浩特地区鸡肉中的沙门氏菌多重耐药现象比较严重。     

Diversity of virulence profiles of Shiga toxin-producing Escherichia coli serotypes in food-producing animals in Brazil

The prevalence, serotypes and virulence profiles of Shiga toxin-producing Escherichia coli (STEC) were investigated in 205 healthy beef and dairy cattle, and 106 goats reared in the southeastern region of Minas Gerais State, Brazil. The prevalence of STEC was 57.5% (61/106) in goats, 39.2%, (40/102) in beef cattle and 17.5% (18/103) in dairy cattle. Among the 514 STEC isolates, 40 different serotypes were found and some of them were identified in a specific host. STEC isolates harboring stx(1) corresponded to 15.6% (28/180), 26.7% (16/60) and 24.1% (66/274) in beef cattle, dairy cattle and goats, respectively. stx(2) was found in 30% (54/180), 53.3% (32/60) and 34.7% (95/274) of beef and dairy cattle, and goats. stx(1) plus stx(2) sequences were harbored by 54.4% (98/180), 20% (12/60) and 41.2% (113/274) of beef cattle, dairy cattle and goats, respectively. The eae sequence was found in 15% (9/60) and 0.6% (1/180) of STEC isolates from dairy and beef cattle, respectively, and the toxB gene was found only in one O157:H7 strain isolated from beef cattle. Strains with the genetic profiles stx(2) ehxA iha saa and stx(1) stx(2) ehxA iha saa were the most prevalent among STEC isolates from cattle. Profiles stx(1) stx(2) ehxA iha, stx(2), and stx(1) iha accounted for 75.5% (207 /274) of the STEC isolates from goats. While STEC strains carrying either stx(2) alone or associated with stx(1) were found more frequently in cattle, those harboring sequences stx(1c) and stx(2d) alone or associated with stx(1c) predominated in goats. Our data show a diversity of STEC strains in food-producing animals, most of them carrying genes linked to severe forms of human diseases.     

Lethal and Sublethal Action of Acetic Acid on Salmonella In Vitro and on Cut Surfaces of Apple Slices

ABSTRACT Antimicrobial action of acetic acid (AA) on Salmonella as affected by acid concentration, exposure time, culture age, and bacterial strains was investigated. Relative susceptibility of 6 Salmonella serovars to AA action was in the following order: S. bareilly > S. typhimurium > S. montevideo > S. poona > S. mbandaka > S. stanley. The stationary-phase cells of S. mbandaka were 100-fold more resistant to AA action than the log-phase cells. A mixture of Salmonella strains at a specified physiological stage should be used when testing the efficacy of the sanitizer treatment. Washing apple disks with NaOCl, H₂O₂, AA, or Na₃P0₄ greatly reduced the number of Salmonella and 30% to 40% of cells that survived were injured. Washing with a mixture of AA and H₂O₂ was the most effective in removing Salmonella from apple disks.     

2020年辽宁省副溶血性弧菌PFGE分型、血清型分布和耐药谱分析

目的 了解辽宁省副溶血性弧菌（VP）的流行特征,为食源性疾病的防控提供可靠的技术支持,提高对食物中毒应急事件的处理能力。方法 对2020年从辽宁省内14个市内食源性疾病病人和食品中分离的VP进行PFGE分子分型、血清学分型、药物敏感试验并分析。结果 44株VP（食源性疾病分离株22株,食品分离株22株）共分为15个血清型,9个血清群,有8株不能进行K分型,不可分型率为18.2%。食源性疾病分离株分为4个血清型、3个血清群,主要血清群为O3,其次为O1;食品分离株分为11个血清型、6个血清群,主要血清群为O2,其次为O1和O3。44株VP对15种抗生素的药敏结果显示,头孢唑啉耐药率高达68.2%,其次是氨苄西林22.7%、红霉素13.6%、阿奇霉素4.5%、头孢西丁2.3%、头孢噻肟2.3%。菌株主要对β-内酰胺类和大环内酯类抗生素耐药,耐药性逐年增强,一些食源性疾病分离株出现多重耐药,且多重耐药株数量逐年增加。食源性疾病分离株较食品分离株耐药率高,血清型O3∶K6为主要流行菌株,且耐药率高,PFGE分子分型按相似度90%以上,可分为5种PFGE优势带型。食源性疾病分离株相似度较高,可聚类成3个组。而食品分离株相似度较低,除了两株菌相似度大于90%外,其余菌株间相似度均在85%以下。结论 O3与O1血清型菌株之间有高度同源性,提示O3与O1血清型菌株密切相关。食品分离株同源性较低,提示食品株间关联性较差。辽宁省2020年VP分离株耐药情况不容乐观,耐药趋势还需进一步关注。