具有痢疾志贺氏7型菌相同抗原的EIEC O_(121)·H~-的分离鉴定

侵袭性大肠杆菌(EIEC)O_(121)·H~-是近几年被人们识别的新血清型,该菌在我国南部地区首先检出,国外资料还见报导,我国北方还未检出。1989年8月我们自陵县一女婴的脓性样便中分得一株与痢疾志贺氏7型血清凝集的菌株,经进一步试验证实为 EIECO_(121)·H~-,现报导如下:一、材料与方法1、菌株待检菌(编号89—103)系自六月龄女婴脓性样便中分得;标准菌痢疾志贺氏7型(菌号51259)和大肠杆菌 O_(121)(菌号44717),均购自中国药品生物制品检定所。     

O157：H7型大肠杆菌病简介

大肠杆菌司空见惯,但是当它获得了新的特性,适应于人体之后,其致病力大大增强。O_(157):H_7型大肠肝菌病两次席卷岛国日本,我国的有关部门及广大群众对此应提高警惕。1 流行情况 O_(157):H_7型大肠杆菌病,是1982年才被认识的,在美国不断发生该菌的食物中毒,至今已发生60多起,其中1993年的中毒,波及     

应用PCR法检测霍乱O_(139)肠毒素

O_(139)霍乱弧菌是第一个能引起霍乱流行的非O_1群霍乱孤菌。它所引起的临床症状和流行特点与O_1群霍乱弧菌引起的霍乱病极为相似,也能产生效泻较强的霍乱肠毒素(CT),具有CTX基因。因此检测O_(139)霍乱弧菌是否携带CT基因,这对了解该菌株的致病力,控制其传播和流行具有重要意义。我们采用PCR技术对本市(1996年)收集的15株O_(139)霍乱弧菌进行CT基因检测,现将检测结果报告如下。     

小肠结肠炎耶尔森菌强毒力岛:结构与功能

小肠结肠炎耶尔森菌强毒力岛(Yen HPI)是最近发现的又一细菌毒力岛,其结构和功能的研究将进一步加深人们对小肠结肠炎耶尔森菌毒力或致病力的认识。本文综述了该毒力岛结构和功能的研究进展。     

宋内志贺氏菌粗糙形体菌株的研究

本研究证明,宋内志贺氏菌除菌落形态光滑的Ⅰ相(D_Ⅰ)和粗糙的Ⅱ相(D_Ⅰ)外,尚有菌落形态粗糙、与Ⅱ相及Ⅰ相血清均凝集、并具有致病力的第三种形体。为了与具有致病力、仅Ⅰ相血清凝集的Ⅰ相(D_Ⅰ)和无致病力、仅Ⅱ相血清凝集的Ⅱ相(D_Ⅱ)区分,建议将这种形体按 Ewing 等的描述用ⅠⅡ相(D_(ⅠⅡ))表示。     

不动杆菌属耐药机制研究进展

不动杆菌属(Acinetobacter)是一群致病力较低的条件致病菌,以往该菌引起的感染很少见,近年来随着β-内酰胺类抗生素和第3代头孢菌素等广谱抗生素的广泛使用,诱导了大量该菌耐药株的产生,该菌的临床分离率越来越高,并形成了对单一抗生素耐药到多重耐药,由低耐药率到高耐药率的发展     

从一份方便米饭中检出乙型溶血性链球菌

目的　从一份日常委托样品方便米饭中检出一株A群β-溶血性链球菌。方法　经生化鉴定该菌株为化脓性链球菌, 结果　该株菌是一株对人类致病力极强的病原菌。11种抗生素药敏试验显示,该株菌对卡那霉素(30ug),萘啶酮酸(30ug), 链霉素(10ug)和磺胺异噁唑(300ug)都耐药。结论　该菌株是一株具有多重耐药性的地方株。     

广东地区212株非O_1群霍乱弧菌血清学分型

本文报道应用国内新研制的一套81种分型血清体系对广东地区212株非O_1群霍乱弧菌进行血清分型试验的结果。在212株菌中有175株可以分型,37株未能定型需要进一步研究。从急性腹泻病人粪便获得的175株菌中共有31个血清型,以O_7和O_2占优势。从水源获得的3株菌中有2个血清型(O_5 和O_8)。从海产品获得的34株菌中有9个血清型,其中O_(12)、O_(16)和O_(28)为优势血清型。试验结果肯定该分型血清系统比较实用,在此基础上应进一步建立一套更简单,分型率更高的血清分型系统。     

用血清学方法诊断O_(157)引起的HUS和HC

近年来,由肠出血性大肠菌O_(157)引起的食物中毒及散发病例屡有报道。有些病人从发病到入院初次就诊这段时间,往往已服用过抗菌药物,因此从粪便中很难查到病原菌。现已知O_(157)菌感染时,急性期病人血清中抗O_(157)LPS的IgM抗体水平明显升高,所以如怀疑是O_(157)菌感染时,对于粪便中未检出该     

从环境中分离小肠结肠炎耶氏菌的新培养基

用小肠结肠炎耶氏菌(下简称耶氏菌)血清群0:3,0:8(对人致病),0:1,2a,3(对动物致病)及来源于环境的0:6,0:5,0:10,0:15、其他肠杆菌科菌株、水及患者粪便样品作了分离耶氏菌的研究。     

一株与侵袭性大肠埃希菌O144诊断血清交叉凝集的蜂房哈夫尼亚菌

[目的]对试验中发现的一株与EIEC诊断血清O144:K?发生凝集反应的蜂房哈夫尼亚菌进行较详细的生化与血清学鉴定,为今后的相关细菌鉴定工作提供参考.[方法]参考国家食品卫生检验标准微生物分册GB/T4789-2003、临床微生物手册中的相关方法进行.[结果]该蜂房哈夫尼亚菌菌株生化不典型,且与EIEC O144:K?血清型存在交叉凝集反应.[结论]该菌株为蜂房哈夫尼亚菌中少数的、生化不典型的菌株,若不进行较详细的生化鉴定易误检为EIEC O144:K?.     

食品中肠出血性大肠埃希菌O157:H7的PCR检测

目的建立快速准确检测食品中肠出血性大肠埃希菌O157：H7的方法。方法采用多重聚合酶链式反应技术（MPCR）特异性扩增肠出血性大肠埃希菌O157：H7的STX、rfbE、fliC基因。结果分别在228，378，709bp处扩增出3个目的基因片段，且只有肠出血性大肠埃希菌O157：H7获得扩增，其他菌种扩增均呈阴性。结论PCR方法比传统细菌检测方法更特异、快速、灵敏和简便，为食品中肠出血性大肠埃希菌O157：H7的快速检测提供了新的手段。     

Generation of a live rabies vaccine strain attenuated by multiple mutations and evaluation of its safety and efficacy

An amino acid substitution at position 333 in rabies virus G protein is known to determine the pathogenicity: strains with Arg or Lys at that position kill adult mice after intracerebral inoculation, whereas strains with other amino acids cause non-lethal infection. Based on those findings, attenuated rabies virus strains have been established and used for oral vaccines mainly for wild animals. However, considering the possibility of back-mutation to the virulent phenotype, a strain that is attenuated by multiple mutations not only in the G protein but also in other viral proteins would be more appropriate as a safe live vaccine. We previously demonstrated that the fixed rabies virus Ni-CE strain, which causes only transient body weight loss in adult mice after intracerebral inoculation, is mainly attenuated by mutations in the N, P and M proteins, while this strain has virulent-type Arg at position 333 in the G protein. In this study, to obtain a live vaccine strain that is attenuated by multiple mutations, we generated Ni-CE mutant, Ni-CE(G333Glu) strain, which has an Arg-to-Glu mutation at position 333 in the G protein, and examined its pathogenicity and immunogenicity. We found that, in contrast to Ni-CE strain, Ni-CE(G333Glu) strain did not cause transient body weight loss in adult mice after intracerebral inoculation. The attenuated phenotype of Ni-CE(G333Glu) strain did not change even after 10 serial intracerebral passages in suckling mice. We also demonstrated that inoculation of Ni-CE(G333Glu) strain induced virus-neutralizing antibody in immunized mice and protected the mice from lethal challenge. These results indicate that Ni-CE(G333Glu) strain is a promising candidate for development of a live rabies vaccine with a high safety level.     

Novel flavivirus or new lineage of West Nile virus, central Europe

A flavivirus (strain 97-103) was isolated from Culex pipens mosquitoes in 1997 following floods in South Moravia, Czech Republic. The strain exhibited close antigenic relationship to West Nile virus (WNV) prototype strain Eg-101 in a cross-neutralization test. In this study, mouse pathogenicity characteristics and the complete nucleotide and putative amino acid sequences of isolate 97-103, named Rabensburg virus (RabV) after a nearby Austrian city, were determined. RabV shares only 75%-77% nucleotide identity and 89%-90% amino acid identity with representative strains of WNV lineages 1 and 2. Another RabV strain (99-222) was isolated in the same location 2 years later; it showed >99% nucleotide identity to strain 97-103. Phylogenetic analyses of RabV, WNV strains, and other members of the Japanese encephalitis virus (JEV) complex clearly demonstrated that RabV is either a new (third) lineage of WNV or a novel flavivirus of the JEV group.     

Detection and molecular characterization of human cosavirus in a pediatric patient with acute gastroenteritis,Japan

Human cosavirus (HCoSV) is a genus recently identified in the family Picornaviridae, which includes important pathogens in human health. The pathogenicity of HCoSV remains unclear. This study reports that an HCoSV strain, 10928/2012/JPN, was identified and collected from the stool sample of a child with acute gastroenteritis in Japan, with the detection rate of 0.16%. The patient was not co-infected with other common diarrhea-causal viruses, suggesting HCoSV as a causal pathogen in this pediatric patient. Phylogenetic and sequence analyses exhibited that the virus strain was classified as a new genotype in HCoSV A species, and this study is first to detect HCoSV in a clinical specimen collected in Japan. These results showed that surveillance of HCoSV is important for detecting viral agents in children with diarrhea, despite being the low detection rate.     

Manipulation of the infectious bronchitis coronavirus genome for vaccine development and analysis of the accessory proteins

Infectious bronchitis coronavirus (IBV) is the cause of the single most economically costly infectious disease of domestic fowl in the UK--and probably so in many countries that have a developed poultry industry. A major reason for its continued dominance is its existence as many serotypes, determined by the surface spike protein (S), cross-protection being poor. Although controlled to some degree by live and inactivated vaccines, a new generation of IB vaccines is called for. Reverse genetic or 'infectious clone' systems, which allow the manipulation of the IBV genome, are key to this development. New vaccines would ideally be: genetically stable (i.e. maintain a stable attenuated phenotype); administered in ovo; and be flexible with respect to the source of the spike protein gene. Rational attenuation of IBV requires the identification of genes that are simultaneously not essential for replication and whose absence would reduce pathogenicity. Being able to modify a 'core' vaccine strain to make it applicable to a prevailing serotype requires a procedure for doing so, and the demonstration that 'spike-swapping' is sufficient to induce good immunity. We have demonstrated that four small IBV proteins, encoded by genes 3 and 5, are not essential for replication; failure to produce these proteins had little detrimental affect on the titre of virus produced. Our current molecularly cloned IBV, strain Beaudette, is non-pathogenic, so we do not know what effect the absence of these proteins would have on pathogenicity. That said, plaque size and composition of various gene 3/5 recombinant IBVs in cell culture, and reduced output and ciliostasis in tracheal organ cultures, shows that they are less aggressive than the wild-type Beaudette. Consequently these genes remain targets for rational attenuation. We have recently obtained evidence that one or more of the 15 proteins encoded by gene 1 are also determinants of pathogenicity. Hence gene 1 is also a target for rational attenuation. Replacing the S protein gene of Beaudette with that from the pathogenic M41 strain resulted in a recombinant virus that was still non-pathogenic but which did induce protection against challenge with M41. We have since made other 'spike-swapped' recombinants, including ones with chimaera S genes. Uniquely, our molecular clone of Beaudette is benign when administered to 18-day-old embryos, even at high doses, and induces immunity after this route of vaccination. Taken together, our results point to the creation of a new generation of IB vaccines, based on rational modification of the genome, as being a realisable objective.     

Transgenic Mice Expressing Porcine Prion Protein Resistant to Classical Scrapie but Susceptible to Sheep Bovine Spongiform Encephalopathy and Atypical Scrapie

How susceptible pigs are to infection with sheep prions is unknown. We show, through transmission experiments in transgenic mice expressing porcine prion protein (PrP), that the susceptibility of this mouse model to bovine spongiform encephalopathy (BSE) can be enhanced after its passage in ARQ sheep, indicating that the pathogenicity of the BSE agent is modified after passage in sheep. Transgenic mice expressing porcine PrP were, nevertheless, completely resistant to infection with a broad panel of classical scrapie isolates from different sheep PrP genotypes and with different biochemical characteristics. The atypical (Nor98 like) isolate (SC-PS152) was the only scrapie isolate capable of transmission in these mice, although with a marked transmission barrier. Unexpectedly, the atypical scrapie agent appeared to undergo a strain phenotype shift upon transmission to porcine-PrP transgenic mice and acquired new strain properties, suggesting that atypical scrapie agent may exhibit different phenotypes depending on the host cellular PrP or other genetic factors.     

Towards a vaccine for attaching/effacing Escherichia coli: a LEE encoded regulator (ler) mutant of rabbit enteropathogenic Escherichia coli is attenuated, immunogenic, and protects rabbits from lethal challenge with the wild-type virulent strain

The ler (LEE encoded regulator) gene product is a central regulator for the genes encoded on the locus of enterocyte effacement (LEE) pathogenicity island of attaching/effacing (A/E) pathogens, including human enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) as well as animal isolates. Although an in vivo role for Ler in bacterial virulence has not been documented, we hypothesized that a Ler deletion mutant should be attenuated for virulence but might retain immunogenicity. The goals of this study were to genetically characterize ler of a rabbit EPEC (rEPEC) strain (O103:H2), to examine the effect of ler on in vivo virulence, and to determine if intragastric inoculation of an attenuated rEPEC ler mutant was immunogenic and could protect rabbits against subsequent challenge with the wild-type virulent parent strain. The predicted ler gene product of rEPEC strain O103:H2 shares high homology (over 95% amino acid identity) with the Lers of another rEPEC strain RDEC-1 (O15:H-) and human EPEC and EHEC. A defined internal ler deletion mutant of rEPEC O103:H2 showed reduced production of secreted proteins. Although orogastric inoculation of rabbits with the virulent parent O103:H2 strain induced severe diarrhea, significant weight loss and early mortality with adherent mucosal bacteria found at sacrifice, the isogeneic ler mutant strain was well tolerated. Animals gained weight and showed no clinical signs of disease. Examination of histological sections of intestinal segments revealed the absence of mucosal bacterial adherence. This result demonstrates an essential role for Ler in in vivo pathogenicity of A/E E. coli. Single dose orogastric immunization with the rEPEC ler mutant induced serum IgG antibody to whole bacteria (but not to intimin). Immunized animals were protected against enteric infection with the WT virulent parent strain exhibiting normal weight gain, absence of diarrhea and absence of mucosally adherent bacteria at sacrifice. Such attenuated ler mutant strains may have potential for use as oral vaccines, or as vaccine vectors for delivery of foreign antigens. It remains to be determined whether such regulatory mutants can protect against infection with A/E bacteria of differing serotypes affecting different hosts.     

安徽省肠出血性大肠杆菌O157:H7宿主动物监测研究

目的了解安徽省肠出血性大肠杆菌O157:H7在宿主动物中的分布及其毒力基因携带状况,为控制O157:H7感染提供依据。方法用免疫磁珠分离法(IMS)对安徽省3个监测点的宿主动物粪便标本进行0157:H7的分离培养,并用多重引物PCR方法(MPCR)检测分离菌株的毒力基因。结果采集宿主动物粪便标本5 560份,检出O157:H737株,阳性率为0.7%,其中牛的阳性率最高,为1.1%。106株O157:H7菌株经过毒力基因测定,65.1%的菌株携带SLT、hly基因。O157:H7感染性腹泻的发病与家禽家畜的带菌正相关(R=0.87,P=0.01)。结论安徽省宿主动物中能检出肠出血性大肠杆菌O157:H7,且菌株携带毒力基因。提示要加强对宿主动物进行O157:H7的流行病学调查和监测工作。     

Plasmid dynamics in Vibrio parahaemolyticus strains related to shrimp Acute Hepatopancreatic Necrosis Syndrome (AHPNS)

Vibrio parahaemolyticus is a causative agent of acute hapatopancreatic necrosis syndrome (AHPNS) which causes early mortality in white shrimp. Emergence of AHPNS has caused tremendous economic loss for aquaculture industry particularly in Asia since 2010. Previous studies reported that strains causing AHPNS harbor a 69-kb plasmid with possession of virulence genes, pirA and pirB. However, genetic variation of the 69-kb plasmid among AHPNS related strains has not been investigated. This study aimed to analyze genetic composition and diversity of the 69-kb plasmid in strains isolated from shrimps affected by AHPNS. Plasmids recovered from V. parahaemolyticus strain VPE61 which represented typical AHPNS pathogenicity, strain VP2HP which did not represent AHPNS pathogenicity but was isolated from AHPNS affected shrimp and other AHPNS V. parahaemolyticus isolates in Genbank were investigated. Protein coding genes of the 69-kb plasmid from the strain VPE61 were identical to that of AHPNS strain from Vietnam except the inverted complement 3.4-kb transposon covering pirA and pirB. The strain VP2HP possessed remarkable large 183-kb plasmid which shared similar protein coding genes to those of the 69-kb plasmid from strain VPE61. However, the 3.4-kb transposon covering pirA and pirB was absent from the 183-kb plasmid in strain VP2HP. A number of protein coding genes from the 183-kb plasmid were also detected in other AHPNS strains. In summary, this study identified a novel 183-kb plasmid that is related to AHPNS causing strains. Homologous recombination of the 69-kb AHPNS plasmid and other naturally occurring plasmids together with loss and gain of AHPNS virulence genes in V. parahaemolyticus were observed. The outcome of this research enables understanding of plasmid dynamics that possibly affect variable degrees of AHPNS pathogenicity.