规模化猪场仔猪水肿病病原菌的分离鉴定

从山西省各地市养猪场采集的发生典型仔猪水肿病的死亡猪肝脏和肠系膜淋巴结等组织器官,分离鉴定出34株溶血性大肠杆菌,用18种大肠杆菌O抗原单价血清进行了血清学鉴定。结果表明,34株分离菌有3株能定型,分属14种血清型,其中以O139(9/34)、O138(4/34)、O9(3/34)3种为优势血清型。同一猪场存在多种血清型,大多数猪场有本场的优势血清型;同一地区的不同猪场流行的主要血清型一般不同;不同地区猪场的优势血清型有的相同,有的不同。     

规模化猪场仔猪源大肠杆菌血清型调查及耐药性检测

从第六师五家渠市7个地区规模化猪场疑似仔猪腹泻病例中采集了361份病料,分离并鉴定其中335份病料的病原为大肠杆菌。采用26种主要大肠杆菌O抗原进行血清型鉴定,结果 258株大肠杆菌可定型,分属17种血清型,其中O14、O65、O157、O24、O138为优势血清型。药敏试验结果显示,分离株对四环素等13种抗菌药的耐药率从14.93%~-97.01%不等,多重耐药从耐2到耐13。研究表明,不同地区猪场分离菌株血清型有所不同,同一地区猪场可存在多个血清型,不同地区可流行同一种优势血清型,分离株表现出不同程度的耐药性,且呈多重耐药。     

新疆塔城地区仔猪黄白痢病原菌的分离鉴定及药敏试验

笔者在塔城市、额敏县、沙湾县30家规模较大的养猪场先后从仔猪黄白痢致死的尸体中分离到30株细菌,每个县(市)分离10株,每个猪场分离1株。经分离培养、形态观察、生化试验、动物试验、血清学方法、细菌鉴定仪等多种方法鉴定的结果为致病性大肠杆菌,血清型K8810株、K994株、F416株、987p4株、未定型6株;药敏试验结果表明这些致病性大肠杆菌均对庆大霉素敏感,但对其它抗菌药物的敏感性各异。     

仔猪水肿病病原菌的分离及血清型鉴定

本试验从山西省长治市某大型猪场采集25份疑似仔猪水肿病病料进行细菌的分离和生化鉴定,分离到大肠杆菌24株,其中致病性大肠杆菌23株.采用微量平板凝集试验,对分离的致病菌进行了血清型鉴定,鉴定出22株共有11种血清型,其中以0139、0138、0141、08血清型最多,共有15株.     

上海地区猪源大肠杆菌血清型及其毒力因子分布调查

对上海地区分离的199株猪源大肠杆菌分离株进行血清型鉴定和毒力因子检测,使用大肠杆菌标准抗O因子血清进行玻片凝集试验;采用普通和多重PCR方法,对分离株进行STa、STb、LT、Stx2e等4种肠毒素和K88、K99、987P、F18、F41等5种黏附素检测。结果:199株猪源大肠杆菌分离株有110株鉴定出血清型,占检测菌株的55.28%,覆盖了30种血清型,优势血清型为O8、O45、O64、O78、O138、O157、O163、O7+O8,占定型菌株的60%。共有32株大肠杆菌检测到毒力因子,阳性率为16.08%,检测出9种毒力因子。其中有21株单独检测到肠毒素,占65.63%,STa和STb+LT阳性的菌株分别为14和4;6株单独检测到黏附素,3株菌株K99阳性;5株同时检测到肠毒素和黏附素。在32株毒力基因阳性的大肠杆菌中,有15株血清型定型,覆盖7种血清型,其中O138、O7+O8与肠毒素STa相关,O8、O45与STb+LT相关。研究表明,上海地区猪源大肠杆菌分离株优势血清型至少覆盖了包括O8、O45、O64、O78、O138、O163等在内的8种血清型;大肠杆菌分离株以产肠毒素为主,主要毒力因子包括黏附素K99和肠毒素STa、STb+LT等。     

仔猪水肿病大肠杆菌的分离鉴定

从云南省昆明市某三个猪场采集41份疑似仔猪水肿病病料进行细菌的分离和生化鉴定,分离到大肠杆菌37株,其中致病性大肠杆菌34株。应用微量平板凝集试验,对分离的34株致病菌进行了血清型鉴定,鉴定出32株共有11种血清型,其中以O139、O138、O141、O8血清型最多,共有24株,占能定型分离致病菌株的75%。     

仔猪水肿病病厌原菌的分离及血清型鉴定

本试验从山西省长治市某大型猪场采集25份疑似仔猪水肿病病料进行细菌的分离和生化鉴定，分离到大肠杆菌24株，其中致病性大肠杆菌23株。采用微量平板凝集试验，对分离的致病菌进行了血清型鉴定，鉴定出22株共有11种血清型，其中以O139、O138、O141、O8血清型最多，共有15株。     

湖北省仔猪水肿病病原的分离鉴定

从湖北省的11 个地市猪场采集34份疑似仔猪水肿病病料进行细菌的分离和生化鉴定,分离到大肠杆菌30 株,其中致病性大肠杆菌28株。应用微量平板凝集试验,对分离的28 株致病菌进行了血清型鉴定,鉴定出25株共有11 种血清型,其中以O 139、O138、O 141、O8血清型最多,共有18 株,占能定型分离致病菌株的72%。     

仔猪水肿病大肠杆菌的分离鉴定

从山西省的10个地市猪场采集38份疑似仔猪水肿病病料进行细菌的分离和生化鉴定,分离到大肠杆菌34株,其中致病性大肠杆菌32株。应用微量平板凝集试验,对分离的32株致病菌进行了血清型鉴定,鉴定出29株共有11种血清型,其中以O139、O138、O141、O8血清型最多,共有21株,占能定型分离致病菌株的72%。     

齐齐哈尔地区猪场仔猪水肿病病原菌的分离鉴定及其药敏性的测定

对齐齐哈尔地区10个市县猪场送检的30份疑似仔猪水肿病病料进行了实验室检查,经过分离培养、形态学检查、生化鉴定、致病性试验,分离到致病性大肠杆菌27株。应用微量平板凝集试验,对分离的致病菌进行血清型鉴定,鉴定结果为,以O138、O139、O9血清型最多,共22株,占分离致病菌的81%。药敏性测定结果显示中,同一猪场不同血清型组的药物敏感性无显著差异,不同猪场相同血清型组和不同猪场不同血清型组的药物敏感性除丁胺卡那外均不同。并依据统计结果排出了9种药物的敏感性顺序。     

Serotypes of Escherichia coli strains isolated from piglets with diarrhea in swine industrial farms

Serotypes of E. coli strains isolated from piglets, which died with symptoms of diarrhea in 9 swine industrial farms, were determined. Large numbers of serotypes (from 16 to 27) in individual farms were detected. The sets of serotypes from 9 investigated farms differed among each other significantly, depending on the farm and time of examination. It was found that more than one serotype of E. coli may exist in the pig body and contribute to the development of disease. The predominant serotypes, i.e. those comprising more than 10% of serologically determined strains, were found to exist in 6 of the investigated farms and not in the remaining ones. Among the predominant serotypes, particularly important seem to be strains with K88 antigen. For prophylaxis of piglet colibacteriosis in industrial farms in Poland two vaccines for sows are recommended: one containing the K88 antigen only and the other the following serotypes: 0149:K91,K88; 020:K57; 020:K83; 0157:K88; 01:K1; 0136:K78; 024:K?; 078:K80 and 0118:K? Strains belonging to these serotypes were the most prevalent in our strain collection.     

共表达K88/987p菌毛产肠毒素性大肠杆菌的分离鉴定及其卵黄抗体的制备

为制备针对一些大型养猪场产肠毒素性大肠杆菌(enterotrxigenic Escherichia coli,ETEC)分离株的特异性卵黄抗体(egg yolk immunoglobulin,IgY),试验对从这些养殖场分离的ETEC分离株菌毛基因类型进行了PCR鉴定,纯化该分离株的菌毛蛋白免疫蛋鸡制备IgY,对该IgY的效价、特异性和体外抑菌效果进行了检测。结果表明,该分离株具有K88和987p 两种菌毛基因,纯化后的分离株菌毛具有较强的免疫原性,经3次免疫后产生的IgY对K88和987p全菌和菌毛的效价可达到1:64 000,分离株菌毛IgY能特异地与K88和987p反应,与K99、F41无交叉反应,5 mg/mL分离株菌毛IgY在体外具有很好的抑菌效果。     

In vitro adhesion of K88ab-, K88ac- and K88ad-positive Escherichia coli to intestinal villi, to buccal cells and to erythrocytes of weaned piglets

The phenotype of 21 weaned piglets, concerning adhesion of Escherichia coli possessing K88ab, K88ac or K88ad fimbriae to pig cells, was determined in an in vitro assay. Comparison was made with adhesion of these three K88 variant strains to buccal mucosal epithelial cells and to erythrocytes (haemagglutination) in the same piglets. Whereas adhesion of the three K88 variant strains to intestinal villi was piglet specific, buccal cell adhesion (BCA) and haemagglutination (HA) were not. The K88ab strain was weakly adhesive or non-adhesive in the BCA and negative in the HA test. K88ac strains consistently gave negative and K88ad consistently gave positive results in both assays. After washing the bacteria with phosphate-buffered saline, the K88ab strain revealed a positive HA test. Neither the BCA, nor HA test can be used to determine the pig intestinal adhesive phenotype.     

Genotype 3 hepatitis E has been widespread in pig farms of Shanghai suburbs

Hepatitis E virus (HEV) genotype 3 was first identified in swine raised on a Shanghai suburban pig farm in late 2006. To accurately determine the prevalence of HEV infections among Shanghai pig farms, 426 pig fecal samples were collected from 37 pig farms located in all 10 Shanghai suburban districts and tested for the presence of HEV RNA using RT-PCR. Genetic analysis based on an amplified 150-bp ORF2 fragment revealed 111 samples to be HEV positive, and the prevalence of HEV infection within the different districts varied between 0 and 41.7%. Thirty-two samples were sequenced, and phylogenetic analysis indicated that 10 isolates belonged to HEV genotype 4 and were most closely related to 3 human and 2 swine HEV strains, all of which had originally been isolated from Asian countries including Japan and China. The remaining 22 isolates belonged to genotype 3 and were most closely related to a strain of swine HEV, US-SW, isolated from pigs in the United States. Our data indicated that genotype 3 HEV was widespread among suburban Shanghai pig farms although further study is required to determine the source and zoonotic nature of the virus.     

Distribution of virF/lcrF-positive Yersinia pseudotuberculosis serotype O:3 at farm level

The distribution and persistence of pathogenic, virF/lcrF-positive Yersinia pseudotuberculosis were investigated in pigs and in the pig house environment during rearing to determine possible contamination routes of early infections. Based on Y. pseudotuberculosis-positive tonsils of slaughter pigs in our previous study, Y. pseudotuberculosis-positive animals were traced back to the farms. Eight farms were visited from 6-10 months later, and a total of 155 pooled and six individual faecal samples from pigs and 116 pooled environmental samples were collected for analysis by different culture methods. Four of the eight farms were found to be Y. pseudotuberculosis-positive. All positive faecal samples were obtained from fattening pigs, with prevalence varying from 5% to 71% on positive farms. Sows, boars and suckling piglets were Y. pseudotuberculosis-negative on all farms. Most Y. pseudotuberculosis-positive farms (three of four) were on a one-site production system, which had a higher prevalence of Y. pseudotuberculosis (5-26%) among fattening pigs than the all-in, all-out system (1-5%). All Y. pseudotuberculosis isolates belonged to serotype O:3 and carried the virF/lcrF gene on the virulence plasmid. Biotypes 2 and 3 were involved, the latter in one isolate and not being previously reported in pigs. Altogether 53 isolates from 16 positive samples were characterized with pulsed-field gel electrophoresis (PFGE). Using SpeI, NotI and XbaI enzymes, four, three and two different PFGE patterns were obtained respectively. A total of nine different genotypes were identified when the profiles of the enzymes were combined. The most common genotypes were gIV, found on three, and gXII, found on two of the four Y. pseudotuberculosis-positive farms. The same genotypes previously detected in pig tonsils were present in pig faeces from the same farm, indicating that some Y. pseudotuberculosis strains can persist in the pig house environment.     

Colonization antigens,antibiotic resistance and plasmid content of enterotoxigenic Escherichia coli isolated from piglets with diarrhoea in galicia (North-Western Spain)

Escherichia coli colonies isolated from 50 diarrhoeic and 29 healthy piglets were investigated for several properties related to pathogenicity, such as production of heat-labile (LT) and heat-stable (STa) enterotoxins, presence of K88 and K99 colonization antigens, mannose-resistant haemagglutinating activity (MRHA), β-haemolysis and antibiotic resistance. The objective was to establish the toxic and adhesive abilities of E. coli strains that cause porcine diarrhoea in Galician farms. Fifty-seven colonies from 14 diarrhoeic piglets formed STa, while no STa⁺ colony was detected from healty piglets. Thirty-four of the 57 STa⁺ colonies were resistant to gentamicin. Sixteen representative STa⁺ strains isolated from the 14 infected piglets were serotyped, investigated for plasmid content and examined by electron microscopy. Of these STa⁺ strains, 15 belonged to serotype 0141:K85ab and carried on their surface the fimbrial antigen P987. The remaining representative STa⁺ strain belonged to serotype 0101:K30 and was K99⁺, being the only STa⁺ strain with MRHA activity. All 15 STa⁺ P987⁺ strains possessed a similar plasmid pattern, with three plasmids ranging in molecular weight from 33 × 10⁶ to 74 × 10⁶; nine of the gentamicin-resistant strains possessed an additional plasmid of molecular weight 16 × 10⁶, which was absent in the six gentamicin-sensitive strains. Strains producing LT or K88 antigen were not detected. Forty-one MRHA⁺ colonies were isolated at similar rates from both diarrhoeic and healthy piglets. Twelve of the 19 non-enterotoxigenic MRHA⁺ strains of which the O-group was established, belonged to serogroups (01, 02, 07, 08, 09 and 075) typical of the human E. coli strains that cause extraintestinal infections. Finally, a statistically significant association between haemolytic and MRHA activities in porcine E. coli was found. In conclusion, it was found that STa⁺E. coli strains belonging to serotype 0141:K85ab:P987 are associated with porcine diarrhoea in Galicia. Additionally, no correlation between the isolation of non-ETEC MRHA⁺ strains and diarrhoea was observed.     

猪繁殖与呼吸综合征病毒湖南分离株ORF5基因的遗传进化分析

为了解猪繁殖与呼吸综合征病毒（PRRSV）在湖南省地方猪保种场的感染情况,本研究在2019－2020年间从湖南省2个地方猪保种场采集287份全血样品。首先将血样混合成41份,采用RT-PCR或PCR法进行PRRSV病原检测,进一步通过高保真PCR扩增从PRRSV阳性样品中扩增PRRSV ORF5基因;测序后利用DNAStar软件分析获得的ORF5基因及其编码的GP5氨基酸与国内外不同PRRSV毒株的遗传进化关系;最后用PRRSV阳性血清接种Marc-145细胞,经盲传分离毒株,并用Reed-Muench法测定病毒滴度。结果显示,检测的41份混样中有3份PRRSV病原核酸呈阳性;从PRRSV阳性混样中单独扩增获得6条PRRSV ORF5基因序列,均属于PRRSV-2型的lineage 8分支,相似性为99.2%~99.8%;6条ORF5基因编码的GP5蛋白氨基酸序列在信号肽区域（第23位）、潜在的N-糖基化位点（第33位）和表位C （第59位）存在差异;PRRSV阳性血清接种Marc-145细胞盲传5代后出现明显的细胞病变,获得1株PRRSV毒株,命名为NX-1,病毒TCID₅₀为4×10⁵/mL。本研究表明,湖南省地方猪保种场存在PRRSV感染,感染的PRRSV属于PRRSV-2型的lineage 8,其GP5氨基酸序列存在的多处变异可能是造成疫苗免疫失败的原因之一,以上结果可为湖南省地方猪保种场的免疫防控提供一定参考。     

猪肺组织中分离的致病性大肠杆菌血清型鉴定

从湖北、湖南、河南、江西、广东等省 2 0个猪场的 1 1 4份肺组织病料中 ,分离获得 3 8株(占 3 3 .3 % )大肠杆菌 ,通过 2 2种主要致病性大肠埃希氏菌 O抗原定型血清鉴定 ,均确定为致病性大肠杆菌 O型菌 ,并分属于 1 6种血清型 ,其中 O14 7、O14 1、O157、O9为优势血清型 ,占 60 .5%(2 3 / 3 8)。     

广西中小规模猪场大肠杆菌病流行情况调查

从广西23家中小规模猪场采集病料,分离、鉴定出致病性大肠杆菌56株,并对其进行血清型鉴定和耐药性检测,结果鉴定出43株致病性大肠杆菌,分属于16种血清型,其中以O₁₃₈、O₁₈、O₈₅、O₉和O₂₁为优势血清型,占定型菌株的69.76%;用20种常用抗菌药进行药物敏感性试验,发现高敏的药物有头孢拉啶、头孢唑啉、头孢曲松、头孢西丁、多黏菌素B、新霉素、壮观霉素和阿米卡星;而不敏感的药物有青霉素、阿莫西林、强力霉素、卡那霉素、万古霉素、林可霉素。说明这些猪场大肠杆菌的耐药性十分严重,应加强生物安全措施等进行综合防控。     

Serological, enterotoxin-producing and biochemical properties of Escherichia coli isolated from piglets with neonatal diarrhea in Norway

Altogether 235 strains of Escherichia coli isolated from jejunal content of piglets with neonatal diarrhea were examined for serological, enterotoxin-producing and certain biochemical properties. Of 198 strains examined, 84 (42 %) belonged to O-group 149, while 14 (7 %) strains belonged to each of the O-group s 8 and 64. Seventy strains (30%) could not be grouped with the sera used. The remaining strains were distributed among the following O-groups with only a few strains in each group: 2,6,9,32,45,98 and 141. Eighty out of 84 E. coli strains of O-group 149 possessed the K88 antigen and produced heat labile enterotoxin (LT). Besides, LT production was demonstrated in 3 out of 14 strains of E. coli 08. K88 antigen was demonstrated in only 1 strain not belonging to O-group 149. Among strains of E. coli 064 12 out of 14 were K99 positive. This antigen was not demonstrated in E. coli strains of other O-groups. A close relationship was demonstrated between strains of E. coli 0149 possessing the K88 antigen and the ability to ferment both raffinose and adonitol. This ability was only detected in 2 other strains of E. coli not belonging to O-group 149.