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1.
In this study the subtype of eae gene was determined by polymerase chain reaction for a total of 59 attaching and effacing Escherichia coli isolated from preweaned (38 isolates) and postweaned (21 isolates) pigs. The eae(beta) gene detected in 19 E. coli from preweaned pigs and 10 E. coli from postweaned pigs was found to be the most common subtype, followed by eae(gamma), eae(epsilon), and eae(zeta) genes. Subtypes were not determined for 7 E. coli isolates. No other subtype of the eae gene was detected in eae+ E. coli evaluated in this study.  相似文献   

2.
The in vitro susceptibilities of 285 isolates of Escherichia coli from preweaned and postweaned pigs with diarrhea and edema disease were tested with the 15 commonly used antimicrobial drugs by an agar dilution minimal inhibitory concentration procedure according to National Committee for Clinical Laboratory Standards (NCCLS) guidelines. All E. coli isolates tested in this study belonged to enterotoxigenic E. coli, attaching and effacing E. coli, or Shiga toxin-producing E. coli. Field isolates had low MIC90 for ceftiofur (1 microg/ml). No correlation in antimicrobial resistance was found in three types of E. coli.  相似文献   

3.
A total of 476 Escherichia coli isolated from weaned pigs with diarrhea and/or edema disease were screened for the presence of the enteroaggregative E. coli heat-stable enterotoxin 1 (EAST1) gene by polymerase chain reaction (PCR). E. coli strains that carried EAST1 genes were also tested by PCR for the presence of genes for five fimbriae (F4, F5, F6, F18 and F41), two heat-stable (STa and STb) and one heat-labile (LT) enterotoxin, and Shiga toxin 2e (Stx2e). One hundred and forty nine (31.3%) of the 476 E. coli isolates carried the gene for EAST1. Of these 149 isolates, 66 (44.3%) carried the east1 gene only and 83 (55.7%) carried genes for the fimbrial adhesins or enterotoxins. E. coli which carried east1 gene also possessed genes for STa or F4 frequently. EAST1 may represent an additional determinant in the pathogenesis of E. coli diarrhea in weaned pigs.  相似文献   

4.
A total of 720 Escherichia coli strains isolated from diarrheic piglets on 756 swine farms were screened for the presence of the enteroaggregative E. coli heat-stable enterotoxin 1 (EAST1) gene by polymerase chain reaction (PCR). Escherichia coli strains that carried EAST1 genes were also tested by PCR for the presence of 4 fimbriae (F4, F5, F6, F41), 2 heat-stable enterotoxins (STa and STb), and 1 heat-labile enterotoxin (LT) gene. One hundred sixty-four (22.7%) of the 720 E. coli isolates carried genes for EAST1. Of these 164 isolates, 62 (37.8%) carried EAST1 genes only, 11 (6.7%) carried genes for at least 1 of the fimbrial adhesins, 51 (31.1%) carried genes for at least 1 of the enterotoxins, and 40 (23.8%) carried genes for at least 1 of the fimbrial adhesins and enterotoxins. Forty-six percent of strains that carried EAST1 genes carried STa genes, and 16% of strains that carried EAST1 genes carried F4. The isolation rate of enterotoxigenic E. coli strains carrying genes for EAST1 gene was 63%. The 6 major genotypes observed in this study (in decreasing order) were EAST1+, EAST1+STa+, EAST1+STa+STb+, EAST1+STa+F5+, EAST1+STa+F4+, and EAST1+STb+F4+. EAST1 is widely prevalent among diarrheagenic strains of E. coli and may represent an important virulence determinant in the pathogenesis of enteric colibacillosis of preweaned pigs.  相似文献   

5.
A total of 604 Escherichia coli strains isolated from weaned pigs with diarrhea or edema disease on 653 swine farms were screened for the presence of the adhesin involved in diffuse adherence (AIDA) gene by polymerase chain reaction (PCR). Escherichia coli isolates that carried AIDA genes were also tested by PCR for the detection of 5 fimbriae (F4, F5, F6, F18, and F41), 3 heat-stable (STa, STb, and EAST1) and 1 heat-labile (LT) enterotoxin, and Shiga toxin 2e (Stx2e) genes. Forty-five (7.5%) of the 604 E. coli isolates carried the gene for AIDA. Of these 45 isolates, 5 (11.1%) carried EAST1 genes only, 1 (2.2%) carried genes for at least one of the fimbrial adhesins, 12 (26.7%) carried genes for at least one of the toxins, and 27 (60%) carried genes for at least one of the fimbrial adhesins and toxins. Fifty-one percent of strains that carried AIDA genes carried Stx2e genes, and 40% of strains that carried AIDA genes carried F18ab. The isolation rate of enterotoxigenic E. coli strain carrying genes for AIDA was 87%, and the isolation rate of Shiga toxin-producing E. coil strain carrying genes for AIDA was 49%. AIDA may represent an important virulence determinant in pigs with postweaning diarrhea or edema disease.  相似文献   

6.
E. coli strains isolated from pigs with postweaning diarrhea or edema disease were tested by phenotypic and genotypic methods for the presence of virulence antigens and genes, respectively. The slide agglutination and ELISA analyses were used for determination of F4, F5, F6, F17, and F41 fimbriae whereas the prevalence of fimbrial fedA and toxin eltI, estI, estII, stx1, stx2 and stx2e genes were recorded by the means of PCR. Only F4 antigen (ac variant) was found in strains of the serogroup O149:K91 isolated from pigs with diarrhea. PCR analyses showed that the fedA gene encoding F18 fimbriae was present in 61.9% of strains isolated from pigs with diarrhea and in 84.2% of strains isolated from pigs with edema disease. The eltI genes encoding heat-labile toxin I (LTI) were present only in 9 out of 21 strains recovered from pigs with diarrhea. Shiga toxin 2 variant (stx2e) genes were found in six isolates from edema disease and also in one strain from diarrhea. The PCR test used in the study was a sensitive and valuable method for determination of virulence factors of E. coli strains.  相似文献   

7.
Enterotoxigenic Escherichia coli (ETEC)-associated post-weaning diarrhea (PWD) is economically one of the most important diseases for the swine industry. Porcine ETEC strains typically express K88 or F18 fimbria and heat-labile (LT) and/or heat-stable (STa, STb) enterotoxins. However, recent studies indicate that EAST1 toxin, adhesin involved in diffuse adherence (AIDA-I) and porcine attaching and effacing-associated factor (paa) may also be expressed by ETEC strains associated with diarrhea. To better understand the virulence factors of E. coli strains that cause PWD, we applied PCR to screen for K88, F18, F41, 987P and K99 fimbrial genes; LT, STa, STb, Stx2e and EAST1 toxic genes; and AIDA-I, paa and EAE adhesin genes in E. coli strains recently isolated from young pigs with PWD in the US. Of 304 E. coli isolates from diarrheic pigs submitted for testing, 175 (57.6%) strains possessed fimbrial genes: K88 (64.6%), F18 (34.3%), F41 (0.57%), K99 (0.57%), 987P (0); toxin genes: LT (57.7%), STb (72.6%), STa (27.4%), STx2e (17.4%), EAST1 (35%); and adhesin genes: AIDA-I (26.9%), paa (60%), EAE (1.1%). All toxin genes except the EAST1 toxin gene, were almost exclusively associated with K88+ or F18+ isolates, and most of these isolates carried multiple toxin genes. The non-fimbrial adhesin paa was found present in over half of the K88+ isolates. A total of 129 (42%) isolates carried no fimbrial genes, including 66 (21.7%) isolates that did not have any of the above virulence genes. These results suggest a broad array of virulence genes associated with PWD in pigs.  相似文献   

8.
Osek J 《The Veterinary record》2002,150(22):689-692
Escherichia coli isolated from pigs with postweaning diarrhoea were examined by PCR for the presence of the O157 rfb gene responsible for the biosynthesis of E coli O157 lipopolysaccharide. Among the 372 isolates tested, 38 (10.2 per cent) were of the O157 serogroup, but none of these possessed the H7 determinant. Further analysis of the E coli O157 isolates revealed that seven of them had the genes responsible for the production of Shiga toxin 1 and eaeA intimin, four other strains had genes responsible for the production of Shiga toxin 2, and four other strains were positive for the enterohaemolysin gene.  相似文献   

9.
Characteristics of verotoxigenic Escherichia coli from pigs.   总被引：14，自引：2，他引：12       下载免费PDF全文
Porcine verotoxigenic Escherichia coli were characterized with respect to frequency of occurrence, serogroup, and association with disease, weaning, and selected properties of the bacterium. Of 668 strains of E. coli from southern Ontario pigs with enteric disease, 32 (4.8%) produced verotoxin at 10(3)-10(7) cytotoxic doses per mL of culture supernatant. Of 22 isolates which belonged to O serogroups 138, 139 and 141, 15 produced verotoxin. Among other enterotoxigenic types of E. coli, two of 57 isolates of O157:K"V17" and two of 96 isolates of O149:K91 were verotoxigenic. The remaining 13 verotoxigenic E. coli belonged to O groups 2, 107, 120, 121 and 130. An additional 21 verotoxigenic E. coli belonging to O groups 138, 139 and 141 and three to O157:K"V17" were identified in a collection of 47 E. coli recovered from weaned pigs with enteric disease. Verotoxigenic E. coli were associated with postweaning diarrhea, bloody stools, sudden death and edema disease. They were isolated at similar frequencies (14%) from healthy weaned pigs, and from weaned pigs with enteric disease. Isolation rates from neonates were low and significantly different from rates in weaned pigs. Neutralizing antibody to verotoxin was not detected in the sera of 45 pigs, which included pigs from herds with a history of edema disease. Verotoxin was not associated with production of colicin, hemolysin, or enterotoxins or with any of 23 biochemical properties of the organisms. The serological data indicate that porcine verotoxigenic E. coli are not a common source of verotoxigenic E. coli for humans. Porcine verotoxin may play a role in postweaning diarrhea and absence of detectable neutralizing antibody in serum may be an important aspect of pathogenesis.  相似文献   

10.
Polymerase chain reaction for 4 fimbriae (F4, F5, F6, F41), 2 heat-stable enterotoxins (STa, STb), and 1 heat-labile enterotoxin (LT) were performed on 400 Escherichia coli isolates to determine their genotype prevalence among enterotoxigenic E. coli isolates from preweaned pigs with diarrhea in the Republic of Korea. A total of 200 of the 400 E. coli isolates were also selected for characterization of the O serogroup. Of these 200 isolates, serogroup could be determined in 139 (69.5%) but not in 61 isolates (30.5%). Isolates of serogroup O101 were the most common, followed in descending order by 08, 020, 0162, 0141, and 0149. Ninety-seven (24.3%) of the 400 E. coli isolates carried genes for at least 1 of the entertoxins or fimbrial adhesins. Of these 97 isolates, 27 carried genes for at least 1 of the fimbrial adhesins and entertoxins. Sixty-six percent of the isolates that carried fimbrial adhesin genes carried genes for at least 1 of the enterotoxins, and 71% of the isolates that carried enterotoxin genes carried genes for at least 1 of the fimbrial adhesins. Genes for the F6 fimbriae were detected in 6% of the E. coli isolates, and F4+, F41+, and F5+ genes were detected in 4.3%, 3.3%, and 2% of the isolates, respectively. Genes for STa, STb, and LT were detected in 10%, 8.5%, and 4.3% of the isolates, respectively. The 6 major genotypes observed in this study (in decreasing order) were F6+, STb+, F41+, STa+STb+, F6+STa+, and STa+.  相似文献   

11.
仔猪腹泻致病性大肠杆菌分型鉴定及耐药性分析   总被引：1，自引：1，他引：0  
为了解贵州省规模化养猪场腹泻仔猪致病性大肠杆菌流行情况及耐药性变化,本研究运用凝集试验、PCR和药敏纸片琼脂扩散法等方法对分离的78株致病性大肠杆菌进行血清型、毒力基因及耐药性分析。结果显示,78株致病性大肠杆菌以O138、O87血清型为主,占定型菌株的60.8%;其中62株致病性大肠杆菌检出毒力基因,检出率为79.5%,可分为8种毒力基因类型,分属肠致病性大肠杆菌（EPEC）、肠产毒性大肠杆菌（ETEC）和肠聚集性大肠杆菌（EAEC）,毒力基因eaeA、elt和escV检出率较高,分别为38.5%、28.2%和21.8%;分离到的致病性大肠杆菌对β-内酰胺类药物高度耐药,均为多重耐药株,耐药种类可达8种以上。结果表明,当前贵州省规模化养猪场腹泻仔猪致病性大肠杆菌的毒力基因检出率较高且基因型复杂,耐药性严重。本试验结果可为规模化养猪场防控仔猪腹泻提供基础资料及理论依据。  相似文献   

12.
河北省犊牛腹泻大肠杆菌致病性及耐药性分析   总被引：1，自引：0，他引：1  
为确定河北省犊牛腹泻大肠杆菌的致病性与耐药性,本研究对2018年1月至2019年6月期间从河北省石家庄、保定、承德、唐山、廊坊的部分肉牛场腹泻犊牛样品中分离到的50株大肠杆菌进行了致病性试验、药物敏感性试验、毒力基因和耐药基因检测。结果显示:50株分离菌均对小鼠具有致病性,致病菌占比100%(50/50)。毒力基因fyuA、irp2、eaeA、ler检出率分别为68.0%、66.0%、34.0%、34.0%。50株分离菌均对15种抗生素中的2种及以上表现为耐药,对10种及以上抗生素耐药的菌株占比达34%(17/50);分离菌对土霉素、磺胺对甲氧嘧啶、磺胺间甲氧嘧啶、替米考星4种药物表现为高度耐药,耐药率分别为90%、90%、94%、100%。除四环素类tetD基因检出率为0外,其它耐药基因均有检出,其中四环素类tetC、氨基糖苷类aadA1、喹诺酮类gyrA、gyrB基因检测率高达100%。试验的50株大肠杆菌均具有较强的毒力和多重耐药性。本研究为河北省大肠杆菌所致犊牛腹泻病的防治提供了实验依据。  相似文献   

13.
A total of 1002 Escherichia coli strains isolated from pre-weaned pigs with diarrhoea on 1114 swine farms were screened for the presence of the adhesin involved in diffuse adherence (AIDA) gene by polymerase chain reaction (PCR). Escherichia coli isolates that carried AIDA genes were also tested by PCR for the detection of five fimbriae (F4, F5, F6, F18 and F41), heat-stable (STa, STb) and heat-labile (LT) enterotoxin, enteroaggregative E. coli heat-stable enterotoxin 1 (EAST1), and Shiga toxin 2 oedema disease (Stx2e) genes. Twenty-three (2.3%) of the 1002 E. coli isolates carried the gene for AIDA. Among 23 isolates shown to carry genes for AIDA, three carried the AIDA gene as the only shown virulence factor. Other isolates carried other virulence factor genes in addition to AIDA. Four isolates carried genes for at least one of the fimbrial adhesins and enterotoxins. Sixteen isolates carried genes for enterotoxins only. The AIDA may represent an additional virulence determinant in pre-weaned pigs with diarrhoea.  相似文献   

14.
Three hundred and twenty-four strains of Escherichia coli isolated from weaned pigs with diarrhoea or oedema disease in Eastern China were screened by multiplex PCR for the presence of the gene encoding adhesin involved in diffuse adhesion I (AIDA-I). Two AIDA-I positive strains were subjected to analysis of the nucleotide sequence of the complete orfA and orfB of the AIDA gene. The AIDA-I positive E. coli isolates were also assessed for five fimbriae (F4, F5, F6, F18 and F41) by monoclonal antibodies and for toxin genes (STa, STb, LT, EAST1, Stx2e) by PCR. Twenty-one (6.5%) of the isolates possessed AIDA-I genes. Of these isolates, two carried AIDA-I genes as the only demonstrated virulence factors, and the remaining isolates carried other virulence factor genes. Comparing the AIDA-I sequence from porcine and human sources, a high homology of orfA both in porcine E. coli and human E. coli was observed. However, each orfB of the two porcine E. coli isolates was 3864 nucleotides long compared with 3861 for the E. coli 2787 orfB, and showed 96.5% homology to E. coli 2787. The data indicated (1) that AIDA-I may be an occasional virulence factor in post-weaning diarrhoea and oedema disease in pigs, (2) that it has the potential to transfer between porcine and human E. coli, and (3) that there is a genetic diversity in orfB between human and porcine E. coli.  相似文献   

15.
This study determined the prevalence of F4, F5, F6, F17 and F41 fimbriae and the genes for FedA (F18 fimbriae), LT and ST enterotoxins, and Shiga toxins Stx1, Stx2 and Stx2e among E. coli isolated from 372 weaned pigs with diarrhea and 46 healthy pigs of the same age. Agglutination tests showed that most isolates were negative for all five fimbrial antigens. The F4 antigen was found in 71 (19.1%) and the F5, F6, or F41 antigen was detected in 6.4% of isolates from diseased pigs. Genes for the F18 fimbriae were detected in 10 (2.7%) strains from diarrheic pigs and in 1 of 46 isolates from healthy pigs. Most isolates (213, 57.3%) from pigs with diarrhea were positive for LTI only or for LTI and STI or Stx2e toxin genes. Fifteen strains (13.7%) possessed only the STI or STII toxin genes. All F4-positive bacteria had genes for LTI or LTI and STI, whereas F18-positive isolates had genes for LTI, LTI/STI, or LTI/Stx2e. Of the strains isolated from diseased pigs, 264 (71.0%) were negative for the fimbrial antigens (genes) examined in this study. The fimbria-negative isolates frequently possessed genetic determinants for LTI (118, 31.7%) or for STII (16, 4.3%) enterotoxins.  相似文献   

16.
Grazing-fed cattle were previously demonstrated to be reservoir of non-O157 Shigatoxigenic Escherichia coli (STEC) serotypes in Argentina. The acid-resistance of some STEC strains makes it reasonable to assume the presence in feedlot of particular STEC serotypes. Fifty-nine animals were sampled every 2 weeks during 6 months by rectal swabs. Twenty-seven of 59 animals (45.8%) were shown to be Stx2(+); 3/59 (5.1%) carried Stx1(+) and 7/59 (11.9%) were Stx1(+) Stx2(+). Among 44 STEC isolates, 31 isolates were associated to 10 O serogroups (O2, O15, O25, O103, O145, O146, O157, O171, O174, O175) and 13 were considered non-typable (NT). Six H antigens (H2, H7, H8, H19, H21, H25) were distributed in 21 isolates whereas 23 were non-mobile (H-). Seventeen of 44 strains (38.6%) were eaeA(+) and 14 (31.8%) harbored the 60MDa plasmid. The megaplasmid (Mp) and eaeA gene were simultaneously found in a limited number of serotypes belonging to the enterohaemorrhagic E. coli (EHEC). E. coli O157:H7 strains, isolated from four (6.8%) animals, corresponded to the Stx2(+), eaeA(+), Mp(+) pattern. Three O157:H7 strains belonged to phage type 4 and the other strain was atypical. Many serotypes isolated from grain-fed cattle (O2:H25, O15:H21, O25:H19, O145:H-, O146:H-, O146:H21, O157:H7, O175:H8) also differed from those isolated by us previously from grazing animals. The serotypes O15:H21, O25:H19 and O175:H8 had not been identified at present as belonging to STEC. This work provides new data for the understanding of the ecology of STEC in grain-fed cattle and confirms that cattle are an important reservoir of STEC.  相似文献   

17.
OBJECTIVE: To determine the prevalence and characteristics of attaching and effacing Escherichia coli (AEEC) in diarrheic and healthy small ruminants. ANIMALS: 502 lambs and kids with diarrhea and 511 healthy sheep and goats. PROCEDURE: Fecal samples from diarrheic and healthy sheep and goats were screened for the eae gene. In addition, E coli isolates with positive results for the eae gene (E coli eae+) were analyzed for the espB gene, production of verotoxins (VT), and serogroup. RESULTS: A significantly higher prevalence of healthy lambs and kids were infected with AEEC, compared with diarrheic lambs and kids and healthy adult sheep and goats. Some differences in the characteristics of E coli eae strains isolated from diarrheic and healthy animals were detected. Thus, the espB gene was detected more frequently among E coli eae+ strains isolated from healthy animals than in those isolated from diarrheic animals, and VT production was only detected in E coli eae+ strains isolated from healthy lambs and kids. The E coli eae+ isolates belonged to several O serogroups. However, 17 of 40 (42.5%) isolates from diarrheic lambs and only 4 of 168 (2.4%) isolates from healthy sheep belonged to serogroup 026. CONCLUSIONS AND CLINICAL RELEVANCE: Our results suggest that E coli eae+ 026 strains may play a role in diarrheal disease in lambs, whereas E coli eae+ strains that also had VT production and eae+ strains that had positive results for the espB gene did not appear to be associated with diarrhea in small ruminants.  相似文献   

18.
To investigate the cause of piglets diarrhea, and the distribution of the serotype and virulence factors of swine Escherichia coli in Beijing, 400 diarrhea samples were collected. TSA serum agar culture method was used to isolate Escherichia coli, serotype identification test and virulence factor genes test were used to verify the presence of O-antigen. 64 strains of E.coli were isolated from 400 diarrhea samples, among which 42 strains of E.coli were classified as 8 serotypes:O101(18.7%),O64(12.5%),O8(10.9%),O20(10.9%),O45(4.7%),O149(4.7%),O2(1.6%) and O89(1.6%), and the major virulence factors were STa, Stx2e, astA and eaeA. There were 8 mainly serotypes that caused piglets diarrhea in Beijing area, among which O101 serotype accounted for the highest proportion. The major virulence factors were astA and eaeA, accounted for more than 50% of all strains, STa and Stx2e accounted for more than 30% of all strains. These data would provide effective data to support the prevention and control of piglet diarrhea in Beijing.  相似文献   

19.
Escherichia coli, a Gram-negative environmental pathogen associated with bovine mastitis was isolated from the milk of 34 symptomatic cows that had been diagnosed with clinical mastitis. Eighty isolates were obtained over a 17-month period and these isolates were screened by DNA amplification for the following E. coli virulence genes: cnf1, cnf2, eaeA, eagg, einv, ltx1, stx1, stx2 and vt2e. Thirty of the bacterial isolates, obtained from 23 different cows, had toxin genes identified in their DNA. The most common virulence gene detected was stx1, with a prevalence of 31%, followed by cnf2 (7.5%), vt2e (6.25%) and eaeA (4%). The possession of different virulence genes by the bacterial isolates had no discernable impact on the health status of the cows as there was no correlation between the potential for toxin production by the E. coli isolates and the systemic clinical condition of the respective infected cows.  相似文献   

20.
本试验旨在调查北京地区仔猪腹泻的原因及猪源大肠杆菌血清型、毒力因子的分布情况。收集北京京郊地区仔猪腹泻样本400份,应用含2%血清的TSA培养基分离大肠杆菌,通过血清型鉴定试验和毒力因子检测验证O抗原。结果显示,400份样本中分离到64株大肠杆菌,定型42株。其主要为O101型（18.7%）、O64型（12.5%）、O8型（10.9%）、O20型（10.9%）、O45型（4.7%）、O149型（4.7%）、O2型（1.6%）、O89型（1.6%）8种血清型,其携带的毒力因子为STa、Stx2e、astA和eaeA等。结果表明,引起京郊仔猪腹泻的大肠杆菌主要有8个血清型,其中O101型发病比例最高。其携带的毒力因子主要为astA和eaeA,占全部菌株的50%以上,STa和Stx2e因子占全部菌株的30%以上。本试验结果将为今后京郊地区仔猪腹泻病的防控提供有效的数据支持。  相似文献   

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