鸡致病性埃希氏大肠杆菌不同菌株间同源性抗原的研究

通过兔制备了３株引起鸡败血症的埃希氏大肠杆菌高兔血清,对分离自新疆不同地区的３０余株鸡致病性Ｅ．ｃｏｌｉ进行了玻板凝集试验和双向免疫扩散试验。结果证明,在琼扩试验中,不同的Ｅ．ｃｏｌｉ菌株间存在着同源性抗原成份,这种同源性抗原在绝大多数Ｅ．ｃｏｌｉ间都有数种之多,但是,这种相互间的同源抗原在玻板凝集试验中有时并不能表现,甚至有沉淀线出现的血清与抗原之间在玻板凝集试验中也不能检测出来。     

鸡致病性埃希氏大肠杆菌的分离与鉴定

内蒙古包头市九原区某鸡场曾发生一起疑似大肠杆菌病。该鸡场饲养200日龄蛋鸡700只,约有半数发病,3d内死亡40多只,且死亡鸡多为同舍,曾用青霉素类药物和痢特灵进行治疗,但疗效较差。因此,笔者对该鸡场送检的病鸡和病死鸡进行了实验室诊断。     

市售常用抗菌药物对鸡致病性埃希氏大肠杆菌的敏感性研究

本试验就鸡致病性埃希氏大肠杆菌（Ｅ．ｃｏｌｉ）用２１种市售抗菌药物进行了敏感性试验和临床治疗，经对１６株鸡致病性Ｅ．ｃｏｌｉ的药敏试验和发病鸡的治疗效果表明，极敏感药物为氟哌酸、庆大小诺霉素、呼拉沙星和喹乙醇。敏感药物为新霉素、禽乐灵、枝原净和吡哌酸。鸡致病性Ｅ．ｃｏｌｉ对卡那霉素、庆大霉素、痢菌净和禽喘灵等药物有不同程度的耐药性。对其它药物不敏感。     

奶牛隐性乳房炎奶样中埃希氏大肠杆菌共同性抗原初探

用LMT的方法对新疆8个奶牛场采集的1020份奶样进行隐性乳房炎的检测,并对阳性样品进行了大肠杆菌的分离与鉴定。从不同牛场分离菌株中挑选8株用家兔制备免疫血清,用试管凝集对从乳房炎奶样分离出的其它21株大肠杆菌进行共同性抗原的筛选。结果显示,免疫血清效价达1∶2560～1∶5120,85.7%的待检菌株与其中3种血清凝集反应呈阳性。对制备血清的8株菌进行SDS-PAGE电泳分析,菌体蛋白图谱显示在20~84 ku处存在大量相同或相似的蛋白条带;用制备的免疫血清进行免疫印迹分析,与8株菌的菌体蛋白在70 ku处呈现明显的抗原抗体反应。说明这些菌株存在共同性抗原。     

鸡大肠埃希氏菌地方菌株的致病性与药敏试验

分别从死亡鸡胚、病死鸡中分离大肠埃希氏菌，进行致病性与药敏试验，并鉴定致病性较强的菌株的血清型。结果表明，所分离的菌株绝大多数对一日龄鸡有致病性，所有血清型对头孢唑啉高度敏感。     

禽脑脊髓炎琼脂扩散沉淀抗原制备与应用的研究

应用禽脑脊髓炎病毒（ＡＥＶ）Ｖａｎ Ｒｏｅｋｅｌ株和内蒙古禽脑脊髓炎（ＡＥ）自然病鸡分离毒株分别接种鸡胚，制出ＡＥ琼扩沉淀抗原。经经验和部分鸡场应用结果表明，该抗原具有良好的特异性。抗原效价为１：３２，可检出不同日龄、品种和不同发病期的人工感染鸡和自然发病鸡血清中的ＡＥ抗体，结果可靠，方法简便，可以推广应用。     

山东省鸡源致病性大肠杆菌O-抗原混合血清型分析

采用抗原抗体凝集反应,用常见的18种O因子血清测定从临床上分离鉴定的182株大肠杆菌的O抗原血清型。结果显示,山东地区鸡源大肠杆菌的优势血清型为O24,O15,O2,O127,O1,O18,O78,占检测菌株的41.21%,同时出现大量混合血清型,占检测菌株的24.18%。这是国内首次报道检测到大量的大肠杆菌O因子混合血清型,印证了国外研究人员对O-AGC核苷酸序列研究的结果,有助于最终对O抗原血清型进行更加准确的分类以及大肠杆菌疫苗的研制。     

猪源致病性大肠杆菌菌毛的提取及菌毛蛋白抗原交叉性研究

本试验对4株猪源致病性大肠杆菌菌毛培养条件进行了研究。试验结果显示,大肠杆菌在TSB培养基中连续传代3次,每次37℃振荡培养48 h,能获得菌毛的大量表达。采用60℃振荡30 min,能使菌毛大量从菌体脱落。从SDS-PAGE和免疫印迹试验可见,20 ku和24 ku菌毛蛋白是这4株大肠杆菌的主要表面抗原。     

Molecular characteristics of ESBL-producing Escherichia coli isolated from chickens with colibacillosis

BackgroundAvian pathogenic Escherichia coli (APEC) causes colibacillosis, resulting in significant economic losses in the poultry industry.ObjectivesIn this study, the molecular characteristics of two extended-spectrum beta-lactamase (ESBL)-producing APEC isolates were compared with previously reported ESBL-producing E. coli isolates.MethodsThe molecular characteristics of E. coli isolates and the genetic environments of the ESBL genes were investigated using whole genome sequencing.ResultsThe two ESBL-producing APEC were classified into the phylogenetic groups C and B1 and ST410 and ST162, respectively. Moreover, the ESBL genes of the two isolates were harbored in different Inc plasmids. The EC1809182 strain, harboring the bla_CTX-M-55 gene on the plasmid, exhibited extensive homology to IncFIB (98.4%) and IncFIC(FII) (95.8%). The EC1809191 strain, harboring the bla_CTX-M-1 gene, was homologous to IncI1-I (Gamma) (99.3%). All chromosomes carried the multidrug transporter, mdf(A) gene. Mobile genetic elements, adjacent to CTX-M genes, facilitated the dissemination of genes in the two isolates, analogous to other ESBL-producing E. coli isolates.ConclusionsThis study clarifies the transmission dynamics of CTX-M genes and supports strengthened surveillance to prevent the transmission of the antimicrobial-resistant genes to humans via the food chain.     

仔猪大肠杆菌病流行株抗性质粒的研究

对分离的２７株猪源性大肠杆菌进行抗性试验,选取１０株双抗性菌株提取质粒ＤＮＡ,电泳分析表明各菌株均存在２～４条质粒ＤＮＡ带。将２１．２２７ｋｂ和５．１４８ｋｂ质粒转化大肠杆菌ＭＣ１０６１／Ｐ３,使其获得了相应菌株的抗性,转化菌纤毛蛋白与Ｋ８８、Ｋ９９高免血清琼扩试验为阴性,证明２１．２２７ｋｂ和５．１４８ｋｂ质粒未携带Ｋ８８、Ｋ９９基因。用２１．２２７ｋｂ转化菌注射小鼠,则小鼠死亡,说明２１．２２７ｋｂ携带毒力基因。     

不同动物源大肠杆菌的耐药性调查

为了解畜禽源大肠杆菌的耐药状况,2011—2012年从患病和健康食品动物中分离鉴定大肠杆菌935株,包括健康猪源606株、患病猪源114株、患病鸡源51株、患病水禽源(鸭和鹅)164株。试验采用琼脂稀释法测定了不同动物来源的大肠杆菌对15种抗菌药物的敏感性。结果发现,大肠杆菌耐药严重,对大部分药物的耐药率超过70.0%,其中氨苄西林、复方新诺明和四环素的耐药率均达到了80.0%以上;仅对头孢西丁、黏菌素和阿米卡星较敏感,但患病水禽源大肠杆菌对阿米卡星的耐药率达到了52.4%,明显高于其他动物。健康畜禽源大肠杆菌对多数抗菌药的耐药率低于患病畜禽源大肠杆菌,表明抗菌药物的使用增加了病原菌对第3代头孢类药物和氟喹诺酮类药物的耐药率,势必增加临床治疗难度。     

Occurrence of fimbriae and enterotoxins in Escherichia coli strains isolated from piglets in Poland.

1125 and 1146 E. coli strains isolated from suckling and weaned piglets with diarrhea, respectively, and 724 strains from healthy piglets were tested for the presence of fibriae and production of enterotoxins. The fimbriae were determined by hemagglutination and slide agglutination tests, enterotoxins—by the use of ileal loop test in piglets (LT and STb enterotoxins) and suckling mouse assay (STa enterotoxin). It was found that 72.8 and 53.0% strains, isolated from diseased suckling and weaned piglets, respectively, possessed specific fimbrial hemagglutinins, in most cases with K88 antigen. Additionally, 987P fimbriae were detected in 14.0 and 0.7% strains isolated from piglets with diarrhea. Only 5 strains (0.7%) recovered from healthy piglets had specific fimbriae, usually with undetermined antigenic structure. F1 fimbriae (called common or unspecific) were found in strains isolated both from diseased (15.2 and 16.3% strains, respectively) and healthy piglets (27.1% strains). It was noted that the strains isolated from suckling and weaned piglets with diarrhea in most cases were enterotoxigenic (90.5 and 69.1% strains, respectively) and most frequently produced heat-labile toxin LT alone or with STb. 18.5% of enterotoxigenic strains isolated from healthy piglets produced STa toxin.     

土鸡屠宰过程中大肠杆菌毒力基因检测及耐药性分析

为了解土鸡屠宰过程中大肠杆菌污染、毒力基因携带及耐药情况,2018年9月-2019年1月在重庆万州、开州、巫溪、奉节4个区县的12个土鸡屠宰地点采集了319份样品,通过菌落形态及显微镜观察、生化鉴定、PCR、药敏试验等方法鉴定分离的大肠杆菌,检测其毒力基因携带和耐药性情况。结果表明：大肠杆菌分离率为22.57%（72/319）,其中餐馆、活禽宰杀铺和定点屠宰点分离率依次为29.73%（22/74）、25.00%（24/96）和17.45%（26/149）,污水、地面、羽毛、用具和胴体分离率依次为75.00%（18/24）、21.62%（8/37）、20.54%（23/112）、17.65%（6/34）和15.18%（17/112）;11种毒力基因中除estA、estB、elt外均被检出,检出率为58.33%（42/72）,共检出14种组合型,有4株分离株4种毒力基因同时存在;分离株对阿米卡星、头孢噻肟最敏感,多重耐药比为90.28%（65/72）,以7~10重耐药居多。土鸡屠宰过程中致病性大肠杆菌污染风险高,多重耐药现象严重,应重视养殖合理用药及屠宰卫生环境。     

猪场粪污中大肠埃希菌磺胺类耐药基因型及表型分析

为了检测猪场粪污中大肠埃希菌对磺胺类药物的耐药状况,用美国临床和实验室标准协会(CLSI)推荐的药敏纸片扩散法检测11株猪场粪污中大肠埃希菌对磺胺类药物的耐药性表型,用multi-PCR Kit检测磺胺类药物的耐药基因(sul1,sul2,sul3)。结果表明,11株猪场粪污中大肠埃希菌对磺胺复合物的耐药率为45%,磺胺二甲基恶唑耐药率为45%,磺胺甲基恶唑耐药率为64%。磺胺类药物的Sul 1基因检出率为100%,sul 2基因检出率为90.9%,sul 3基因检出率为36.4%,磺胺类抗生素耐药基因的总检出率为100%。研究结果可为大肠埃希菌的耐药性研究以及磺胺类耐药机制的研究提供科学依据。     

Characterization of shiga toxin-producing Escherichia coli strains isolated from calves in Poland

Fecal samples from 67 3–5-months-old calves with diarrhea were screened for the presence of shiga toxin-producing Escherichia coli (STEC). Several accessory virulence factors genes were also tested. Among 192 E.coli isolates tested, 15 (7.6%) were found to harbour the shiga toxin 1 or 2 (stx1 or stx2) genes. The stx2-carrying samples were further subtyped by PCR for the stx2c, stx2d, and stx2e toxin variants. It was shown that stx2-positive bacteria mainly possessed the stx2c shiga toxin type gene. The enterohemolysin (hlyA) and intimin (eae) genes were found in seven (46.7%) STEC strains whereas the cytotoxic necrotizin factor 1 and 2 or the P fimbrial genes were detected in two isolates only. This study confirmed that calves are a reservoir of STEC strains (with all pathogenicity genes) that may be virulent for humans.     

鸭源致病性大肠埃希氏菌生物学特性的研究

对从自然病例鸭实质脏器中分离的致病性大肠埃希氏菌的生物学特性进行了观察。结果表明，不同血型和同一血清型不同菌株的培养特性、生化试验基本一致，抗生素耐药性呈多重性，所有菌株均能使小鼠和雏鸭发病死亡。     

我国猪源和鸡源大肠杆菌抗生素耐药性相关基因研究进展

大肠杆菌作为一种条件致病菌和重要的耐药性指示菌,国内外已有大量猪源、鸡源大肠杆菌耐药性相关基因的研究报道.受动物种属、地域等来源性差异,以及耐药机制、亚型等因素的影响,研究中涉及很多种不同的耐药性相关基因,且检出率也不尽相同.根据耐受抗菌药物种类,对这些基因作用机理及分布情况等方面综述,以期为研究大肠杆菌耐药性产生机制...