潍坊地区肉鸡致病性大肠杆菌的血清型鉴定

从山东潍坊地区不同鸡场采集病料,经生化试验和血清型鉴定了95株大肠杆菌,其中78株为致病性大肠杆菌,这78株大肠杆菌的O血清型覆盖了14种血清型,其中O78、O2、O15、O11为优势血清型。     

山西省致病性猪大肠杆菌分离及生物特性研究

研究从山西省主要养猪区80多个养猪场(户)的病死猪及疑似大肠杆菌病猪粪便、肠道、肛门等部位采集病料接种于营养琼脂平板、麦康凯琼脂平板、伊红美蓝培养基等纯化培养,将疑似菌落革兰氏染色、镜检;对初步分离菌经生化试验、致病性试验、大肠杆菌O抗原血清型鉴定等,对山西省流行的猪大肠杆菌病病原进行生物学特性研究。研究结果表明,病原菌纯化、镜检结果有123株疑似菌株符合猪大肠杆菌形态特征;生化试验中有8株病原菌产生H2S,有5株病原菌VP试验、枸橼酸盐利用试验是阳性,这13株病原菌不符合猪大肠杆菌的生化特性,其余110株病原菌符合大肠杆菌生化特性;致病性研究结果表明有97株病原菌是致病性猪大肠杆菌;大肠杆菌O抗原血清型鉴定结果:94株血清型分属于36个血清型,其中O138、O101、O9、O107、O141有35株,共占所鉴定分离菌株的37.2%,这几种血清型均为山西这80多个猪场目前流行的优势血清型,通过鉴定摸清了流行在山西省猪致病性大肠杆菌血清型特点、优势血清型菌株及分布状况。这一研究结果为山西省制定猪大肠杆菌病防治策略提供了依据。     

河南部分地区家兔大肠杆菌病病原分离鉴定与药敏试验

无菌采集不同地区临床上疑似为兔大肠杆菌病的10只病死兔典型材料，进行细菌学检验，鉴定出10株兔大肠杆菌。将分离菌株分别接种试验动物，对小白鼠致死率达100％。经大肠杆菌O因子血清鉴定，7株为01193株为O21。药敏试验表明，10株大肠杆菌中多数菌株对壮观霉素、头孢唑啉、新霉素和痢特灵敏感。     

锦州地区鸡源大肠杆菌的分离鉴定

为了摸清锦州地区鸡源大肠杆菌的血清型,为防治工作提供依据,选取锦州市5个县区13个鸡场78只临床诊断为大肠杆菌病的病鸡,通过细菌分离培养、生化试验、致病性试验、血清学试验进行鉴定。结果显示:共分离到55株大肠杆菌,分离率达70.51%;其中有41株为致病性菌株,占分离菌总数的74.55%;致病性大肠杆菌血清型有11种,未定型2种,其中优势血清型为O78、O1、O23、O2。     

甘肃省鸡大肠杆菌病血清型调查及药敏试验

从388份病死鸡的肝脏、脾脏等病料,分离出致病性埃希氏大肠杆菌28株。对28株大肠杆菌用11种O因子血清进行鉴定,其中15株为O78,占53.57%,10株为O1,占35.71%,表明O1、O78是我省鸡源性大肠杆菌的优势血清型。药敏试验表明,12种抗菌药物中对大肠杆菌敏感性最强的是阿米卡星和头孢唑啉。     

南阳市鸡致病性大肠杆菌的分离、鉴定及药敏试验

从南阳地区各养鸡场的发病鸡中分离出大肠杆菌,经常规方法培养、纯化、镜检及生理生化鉴定。分离出29株鸡致病性大肠杆菌。有14株分离株被鉴定出血清型,其中O1为4株,O2为3株,O78为7株,O1,O2和O78血清型占分离株总数的48．3％。未定型15株,用29株分离菌株分别接种供试雏鸡后,发病症状及剖检病变均符合本病特征,其中高致病性菌株有13株,中度致病菌株有9株,低致病性菌株有7株,分别占试验菌株总数的44．8％、31％和24．2％。采用22种药敏纸片对29株分离菌进行药敏试验,结果表明,分离出的大肠杆菌耐药性相当普遍,仅对头孢噻肟、丁胺卡那霉素、壮观霉素及新霉素等药物敏感性较高。     

致病性大肠杆菌苗用菌株的原生质体融合的研究

对筛选的5株大肠杆菌(E2:O2、E6:O78、E7:O8、E9:O9、E22:O138)进行药敏试验以及致病性大肠杆菌原生质的制备、融合和筛选试验。结果表明:①5株大肠杆菌对多种抗菌素存在抗药性,并且这种抗药性能进行培育,同时,在原生质的融合过程中能递进;②大肠杆菌原生质体选择的最佳组合是:溶菌酶2.0 g/L,处理时间是20 m in;③大肠杆菌的融合率在10-8左右,大肠杆菌之间的融合率为10-6左右;共选出3株融合菌株为E2-E6、E6-E7和E2-E22,各融合株的生化特征介于起源菌株的生化特征之间,有2株融合株的抗原特征含原菌株各自的抗原成分。     

海安县鸡大肠杆菌病病原的分离鉴定及多价灭活苗的研制

为了确定海安县鸡大肠杆菌病的病原并研制多价灭活苗,试验对从海安县兽医站门诊及12个大型养殖场具有疑似大肠杆菌病病变的252只病死鸡进行了病原分离及鉴定。结果表明:共分离、鉴定出大肠杆菌226株,定型198株;共测出23个血清型,其中O78(32株)、O18(26株)、O2(21株)、O88(17株)、O1(13株)、O11(10株)6种血清型占定型菌株的60.1%,为海安县大肠杆菌优势血清型;将此6种优势血清型大肠杆菌制成多价灭活苗免疫雏鸡,安全性好,保护率高。     

河北省鸡病原性大肠杆菌的分离与鉴定

从河北省不同地区的发病鸡场分离培养出91株大肠杆菌，经致病力试验鉴定为病原性大肠杆菌，血清学鉴定，除有23株未能定型外，其余68株共鉴定出13个血清型，其中以O78、O2、O111、和O35等5个血清型检出率较高，分别占定型菌株的33．80％、26．50％、11．80％、5．88％和5．88％，而O78，O2和O111仅3个血清型却拥有49个分离株，占定型菌株的72．10％。     

枣庄地区仔猪腹泻大肠杆菌O抗原血清型调查

为掌握枣庄地区致仔猪腹泻大肠杆菌的流行情况,阐明O抗原血清型分布,在枣庄市下属各县(市、区)部分养猪场采集病料,进行了大肠杆菌的分离培养、生化试验、O-抗原血清型鉴定、毒力试验及致病性回归试验等相关研究。结果表明:分离株分属于16个血清型:O15、O25、O27、O44、O45、O63、O78、O85、O125、O126、O127、O128、O142、O143、O152、O158,其中O15(10株)、O44(14株)、O45(11株)、O63(20株)、O78(8株)、O126(15株)血清型菌株占到总量的67.2%;毒力试验结果显示O44、O45、O126三种血清型致病力最强。说明枣庄地区致仔猪腹泻大肠杆菌有独特的血清型构成,在疾病防治过程中应引起重视。     

Comparative study of colonizing and noncolonizing Campylobacter jejuni

Campylobacter jejuni A74/O and A74/C are congenic strains. An oral dose of 10(5) organisms of strain A74/C colonizes chicken intestines. Strain A74/O, from which A74/C is derived, does not colonize the chicken intestines with an oral dose of 10(5) organisms. In this study, the congenic bacteria were compared to identify possible colonization mechanisms. Differences were not observed in plasmid content or by HindIII, Pst I, Acc I, HincII, Ava I, Ava II, Xba I, and BamHI restriction enzyme digestion of total DNA. Transmission electron microscopy of negatively stained samples revealed no differences between the strains. Sections of cecal tissue from nonfed day-of-hatch chicks were cultured with each strain for 2 hours and then examined by light and electron microscopy. Both strains caused necrosis of villus epithelial cells. Immunofluorescent or silver staining revealed strain A74/C located deep in numerous epithelial crypts, but strain A74/O only was present in one sample mixed with sloughed necrotic cells. Similarly, organisms were detected by transmission electron microscopy deep in crypts in tissues cultured with A74/C, but not A74/O. Cells of A74/C detected in crypts did not appear to associate with epithelial cells. The strains did not differ in chemotactic behavior to mucin or fucose.     

鸡传染性法氏囊病病毒山东地方野毒株的分离与鉴定

从山东省多个地区患传染性法氏囊病的鸡群中，分离到５个野毒株，经过琼脂双向双扩散试验、ＥＬＩＳＡ试验、血凝试验、病毒感染力测定、回归试验、电镜观察等６项鉴定，证明是鸡传染性法氏囊病病毒。并且，各毒株毒力差异较大，有的毒株感染力相当强，ＥＬＤ５０／０．２ｍＬ＝１０６．００。     

Isolation and characterization of type 1 fimbriae from a chicken pathogenic Escherichia coli serotype O78.

Type 1 fimbriae from chicken pathogenic Escherichia coli strain PDI-386 (serotype O78) was purified and characterized. Because of the acid-induced autoagglutination (T. Sekizaki, Y. Nakasato, and I. Nonomura, J. Vet. Med. Sci. 54, 493-499, 1992), the fimbriae could be easily purified by repeating acid sedimentation, washing, and dissolving in buffer (pH 8.0). In electron microscopy, the purified fimbriae showed a filament of 8 nm in diameter and 10 microns in average length. The molecular mass of the protein subunit of the purified fimbriae estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was 19,000 daltons. The amino acid composition and its NH2-terminal sequence were similar to the previously described one of the Klebsiella pneumoniae type 1 fimbriae. Moreover, there was an immunological relatedness between them. These results indicated that a molecular diversity found between the fimbriae of E. coli and that of K. pneumoniae has already been existed among chicken pathogenic E. coli strains.     

Serotypes and Shiga toxin genotypes among Escherichia coli isolated from animals and food in Argentina and Brazil

Shiga toxin (Stx)-producing Escherichia coli (STEC) strains isolated from animals and food in Argentina (n=44) and Brazil (n=20) were examined and compared in regard to their phenotypic and genotypic characteristics to evaluate their pathogenic potential. The clonal relatedness of STEC O157 isolates (n=22) was established by phage typing (PT) and pulsed-field gel electrophoresis (PFGE). All O157 strains studied carried eae and enterohemorrhagic E. coli (EHEC)-hly sequences. In Argentina, these strains occurred both in cattle and meat, and 50% of them carried stx2/stx2vh-a genes, whereas in Brazil the O157 strains were isolated from animals, and most harbored the stx2vh-a sequence. At least 13 different O:H serotypes were identified among the non-O157 strains studied, with serotype O113:H21 being found in both countries. All but one non-O157 strains did not carry eae gene, but EHEC-hlyA gene was found in 85.7% of them, and the stx2 genotype was also more prevalent in Argentina than in Brazil (P<0.01), where stx1 alone or in association was most common (68.8%). One STEC strain isolated from a calf in Brazil harbored the new variant referred to as stx2-NV206. PFGE analysis showed that STEC O157 strains were grouped in four clusters. One Brazilian strain was considered possibly related (> or =80%) to Argentinean strains of cluster I. Differences in the pathogenic potential, especially in regard to serotypes and stx genotypes, were observed among the STEC strains recovered from animals and food in both countries.     

Virulence markers and genetic relationships of Shiga toxin-producing Escherichia coli strains from serogroup O111 isolated from cattle

Shiga toxin-producing Escherichia coli (STEC) strains isolated from healthy cattle (O111:NM, seven strains; O111:H8, three strains) in Brazil were studied and compared to previously characterized human strains in regard to their phenotypic and genotypic characteristics to evaluate their pathogenic potential. Most bovine STEC O111 strains were isolated from dairy calves, and strains with genotypes stx1 alone and stx1/stx2 (variant stx2) occurred in different regions. Irrespective of the stx genotype, all strains were positive for eae theta, alpha variants of tir, espA and espB, and for ler, qseA, iha, astA and efa1 genes. Only one strain was negative for EHEC-hlyA and all strains were negative for iha, saa and espP genes and for EAF and bfpA, genetic markers of EPEC. Except for the presence of stx2, bovine strains showed the same profile of putative virulence genes found among the human strains. Similar biochemical behavior was identified among the strains analysed. Two bovine STEC strains produced the localized adherence (LA) phenotype in 6-h tests with Caco-2 (human enterocyte) cells. Intimate attachment (judged by the FAS test) was found in 9 out of 10 bovine strains as it was observed for the human STEC strains. RAPD-PCR analysis showed two distinct RAPD groups among the STEC O111 strains examined. Despite the relative low frequency of STEC O111 strains recovered from cattle no differences in their pathogenic potential were observed compared to some strains isolated from human diarrhea, suggesting that healthy cattle may be a potential source of infection for humans in Brazil.     

不同品系鸡血浆转铁蛋白、血红蛋白和红细胞酯酶D多态性研究

采用聚丙烯酰胺凝胶等电聚焦电泳法测定了6个品系鸡的血浆转铁蛋白(Tf)、血红蛋白(Hb)和红细胞酯酶D(EsD)的遗传多态性.转铁蛋白出现5种表型,受Tf~A、Tf~B、TP~C3个共显性等位基因控制;血红蛋白出现5种表型,受Hb~F、Hb~(M1)、Hb~(M2)3个共显性等位基因控制;红细胞酯酶D出现5种表型,受EsD~1、EsD~2、EsD~3、EsD~4、EsD~55个共显性等位基因控制.各品系鸡之间的Tf、Hb、EsD的基因频率是不同的.根据基因频率计算遗传距离并用类平均法进行聚类分析.3种肉用鸡中艾维茵和塔特姆亲缘关系最近,罗斯褐鸡与3种肉用鸡亲缘关系较近,而与其它蛋用型鸡亲缘关系较远.     

鸡传染性支气管炎病毒血凝谱的研究

用家兔A型魏氏梭菌培养液处理的6株鸡传染性支气管炎病毒,以方阵试验分别与人O型红细胞及羊、猪、兔、鸡、鸭、鹌鹑、麻雀、小鼠等8种动物的红细胞作血凝试验,结果证明,鸡传染性支气管炎病毒H_(120)株和M_(41)株均能凝集人O型以及羊、猪、兔、鸡、鸭、鹌鹑、小鼠的红细胞,而不能凝集麻雀的红细胞;GIBV株和Connecticut株能凝集人O型以及免、鸡、鹌鹑、麻雀的红细胞,而不能凝集猪、羊、鸭、小鼠的红细胞;Gray株能凝集兔、鸡、鹤鹑的红细胞,不能凝集人O型以及猪、羊、鸭、麻雀、小鼠的红细胞;而经家兔A型魏氏梭菌培养液处理的T株和未经处理的6株病毒对人O型以及8种动物的红细胞都没有凝集性。试验还证明,M_(41)株和H_(120)株对人O型及8种动物的血凝活性水平有差异。     

Isolation and molecular analysis of colonising and non-colonising strains of Campylobacter jejuni and Campylobacter coli following experimental infection of young chickens

Fourteen-day-old chickens were inoculated with selected Campylobacter coli and C. jejuni strains. C. jejuni strains were of two subgroups based on a polymorphism detected using a DNA probe and represented the profiles typical for the majority of strains of either chicken or human origin. All C. coli strains previously isolated from humans colonised chickens, whereas from 4/7 C. jejuni strains of human origin, failed to colonise. Of 12 Campylobacter strains of chicken origin, 10 established a persistent colonisation in the chickens, and 2 strains colonised poorly or not at all. Four strains that failed to colonise chickens were each inoculated into groups of five birds. Three strains again did not colonise any of the chickens and the fourth strain colonised four out of the five chickens, but was poorly excreted. When infected chickens were placed in the same enclosure to facilitate interchange of strains, C. jejunistrain 331 was found to be dominant and colonised all 12 chickens by 21 days, displacing all other strains. C. jejuni strain 331, was then inoculated into groups of five birds with previously established colonisation by C. jejuni and C. coli strains. Strain 331 was able to replace the C. jejuni strain in all five birds but established co-colonisation with C. coli strain. Naturally occurring co-colonisation by two C. jejuni strains was detected in one chicken out of 200 tested. There was no obvious correlation between the type of DNA polymorphism in strains of chicken origin and their ability to colonise chickens.     

致肾脏、肠道病变大肠杆菌的分离及生物特性鉴定

利用常规培养基从病鸡的肾脏、肠道等组织器官中分离出了二株大肠杆菌，血清型为0152-160，该菌株能引起7／10的10日龄SPF鸡胚死亡，死亡鸡胚肾、肝肿大，全身出血。用分离物1^#、2^#大肠杆菌感染的20日龄雏鸡67％～88％死亡，从试验发病死亡鸡肾脏分离到的大肠杆菌仍能67％的感染鸡死亡。死亡鸡呈严重的肾肿大、尿酸盐沉积，肠壁出血、粘膜脱落，气囊炎和心包炎。该大肠杆菌对SPF鸡的致病死亡率低于普通健康鸡；试验证明用鸡毒支原体激发感染，可明显增强该大肠杆菌对SPF鸡的致死率和病变程度。另外试验证明此大肠杆菌对青、链霉素、庆大霉素等具有强耐药性。     

4株NDV流行株的分离鉴定、生物学特性及遗传学特性的研究

为研究近年国内的新城疫病毒（Newcastle disease virus,NDV）流行株与传统疫苗株（Mukteswar、La Sota及Clone 30）的亲缘关系和遗传演化情况,试验从广东、广西和海南地区患病的免疫鸡群病料中分离鉴定得到4株NDV流行株。通过RT-PCR技术对各毒株的F和HN基因进行扩增、克隆与序列分析,然后与GenBank上发表的NDV序列进行同源性比对、遗传进化树分析,并测定各毒株致病指数。结果显示,本试验中HN-08株的鸡胚半数感染量（EID₅₀）、平均死亡时间（MDT）、脑内致病指数（ICPI）和静脉致病指数（IVPI）分别为10^-8.37/0.2 mL、58.5 h、1.78和2.45,XX-08株分别为10^-6.50/0.2 mL、75.0 h、1.61和2.41,YS-09株分别为10^-7.75/0.2 mL、64.5 h、1.71和2.38,LF-09株分别为10^-7.60/0.2 mL、63.8 h、1.84和2.38。4株鸡源NDV流行株彼此间F和HN基因推导的氨基酸序列同源性在95.8%以上,与鸡源流行株GX11/03、GM株的同源性为96.8%~98.6%,而疫苗株Mukteswar、La Sota及Clone 30株的同源性为86.7%~90.6%,与标准强毒株F₄₈E₉的同源性为88.4%~91.3%。表明4株NDV流行株均为强毒株,与近年来国内流行的GX11/03、GM株有较近的亲缘关系,而与传统疫苗株的关系相对较远。