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1.
The OK antigens and the fimbriae F4 of E. coli with haemolysis isolated from 113 cases of oedema disease and/or diarrhoea were identified serologically. The genes for F18 and for enterotoxins LT, STIa and STII as well as Shigatoxin Stx2e were determined by PCR. Fimbrial variants F18ab and F18ac were distinguished by means of indirect immunofluorescence on smears prepared from the intestinal mucosa and from cultures grown under appropriate conditions. Adhesive fimbriae were detected with every case or isolate, respectively, by means of at least one out of the techniques mentioned above. The serogroup O149:K91 with fimbriae F4ac (K88ac) and genes for the enterotoxins LT and STII was most prevalent. Serogroup O139:K12 with fimbriae F18ab and the gene for Stx2e was second, whereas serogroups O141ab and O141ac with fimbriae F18ac and genes for Stx2e, STII and often LT were much less prevalent. The serogroup O147:K89 with fimbriae F18ac, and genes for STIa and STII was detected for the first time in Switzerland.  相似文献   

2.
F18+ Escherichia coli cause postweaning diarrhoea and oedema disease in newly weaned piglets. Protection against these diseases can be established by preventing the fimbrial adhesion of these bacteria to the enterocytes of the porcine intestine. To test a vaccine against F18+ E. coli consisting of the adhesin of F18 fimbriae, FedF, the conservation of the FedF subunit had to be examined. Therefore, the fedF sequence of 37 F18+ E. coli isolates from different countries was determined and compared to the fedF gene of the F18ab reference strain F107/86. The amino acid sequence of the mature FedF from the individual F18+ E. coli isolates was 96–100% identical to that from E. coli F107/86, but the overall homology was 90.4%. Hyper variable regions were not found in the FedF sequence. The FedF sequence was conserved over the different countries and between the two antigenic variants, F18ab and F18ac, suggesting that F18ab and F18ac strains have the same receptor. Furthermore, the conserved C-terminal region in the FedF adhesin suggests that the F18 fimbriae, in analogy with type 1 and P pili, are assembled by a donor strand mechanism. In conclusion, the reported conservation of FedF supports the usefulness of the fimbrial adhesin as a subunit vaccine against F18+ E. coli infection.  相似文献   

3.
Post-weaning diarrhoea and oedema disease in weaned piglets are caused by infection with F4+ or F18+ Escherichia coli strains. There is no commercial vaccine available, but it is shown that oral immunization of weaned piglets with purified F4 fimbriae induces a protective mucosal immune response. In the present study, piglets were orally and nasally immunized with purified F18 fimbriae in the presence of the mucosal adjuvant LT(R192G) or CTA1-DD, respectively. This immunization could not lead to protection against F18+ E. coli infection. The induced F18-specific immune response was directed towards the major subunit FedA and weakly towards the adhesive subunit FedF. The results of these experiments demonstrate that it is difficult to induce protective immunity against F18+ E. coli using the whole fimbriae due to the low response against the adhesin.  相似文献   

4.
Different vaccines against Escherichia coli diarrhea of piglets were applied parenterally in pregnant sows at an industrial fattening farm. The following vaccines were used: vaccine No. 1 with non-complete Freund's adjuvant. Tween 80 and Arlacel A, comprising O149:K91,K88; O139:K82; O8:K87,K88; O141:K85,K88; and O64:K? E. coli serotypes; vaccine No. 2 with paraffin oil instead of Freund's adjuvant, comprising the same E. coli serotypes as the vaccine No. 1; stable specific vaccine with 10% aluminium hydroxide, based on E. coli serotypes most frequently isolated from piglets which died at the farm (O149:K91,K88; O8:K87,K88; O20:K17; O64:K?); Gletvax K88 (Wellcome) and NOBI-VAC LT-K88 (Intervet International). The number of piglets which died up to the moment of weaning in comparison to the number of born ones was considered as an indicator of acquired protection. It was found that the most effective in conferring protection against E. coli diarrhea were: vaccine No. 1 and NOBI-VAC. The differences in the mortality rate between piglets originating from sows vaccinated with these vaccines and those from unvaccinated ones were statistically significant (P < 0.05). No significant differences were noted between controls and animals vaccinated with the remaining vaccines.  相似文献   

5.
A total of 114 avian pathogenic Escherichia coli (APEC) isolates were collected from cases of colisepticaemia occurring in broilers (77) and layers (37) within Ireland. In addition 45 strains isolated from faeces of healthy birds were included for comparison. All isolates were serogrouped, and examined for known virulence factors, mostly by PCR. The O78 serogroup represented 55 and 27% of broiler and layer colisepticaemic isolates respectively. All isolates were positive for curli fimbriae (crl, csg) and negative for afimbrial adhesin (afa). S-fimbrial (sfa) sequences were present in 8.8% of septicaemic isolates and 8.9% of healthy bird isolates. The majority of E. coli from cases of colisepticaemia (97.4%) and healthy bird (95.6%) isolates were positive for aerobactin (aer), and temperature sensitive haemagglutinin (tsh) was similarly detected in high numbers in 93.9 and 93.3%, respectively. In comparison to E. coli isolates from the faeces of healthy birds, a significantly higher percentage of isolates from septicaemic cases possessed Type 1 fimbriae (fimC) and increased serum survival (iss) gene sequences. Forty-seven (41.2%) isolates from septicaemic birds possessed P-fimbriae (pap) gene sequences, compared with only 15.6% from E. coli isolated from healthy birds. Haemolysin (hlyE) sequences were detected in 46.7% of isolates from healthy birds in comparison with 6.1% of septicaemic isolates. Sequences encoding colicin V (cvaC) were detected in 99.1% of septicaemic isolates and 82.2% of isolates from healthy birds. The K1 capsule was only present in two septicaemic isolates, both taken from layers. Motility was detected in 36.8% of E. coli isolated from cases of septicaemia, compared with 93.3% of isolates from healthy birds. These results demonstrate the presence of 11 virulence genes in E. coli isolated from cases of colisepticaemia within Ireland, and indicate the prevalence of iss and fimC.  相似文献   

6.
The presence of the astA gene responsible for production of enteroaggregative Escherichia coli heat-stable enterotoxin 1 (EAST1) was examined in E. coli strains isolated from pigs with postweaning diarrhoea. Two hundred and seven isolates were tested using PCR for the astA marker and for heat-labile I (LTI), heat-stable I (STI), and heat-stable II (STII) enterotoxin genes. Moreover, the isolates were also analysed for their serotypes (O and K antigens) as well as for fimbrial adhesins using agglutination methods. It was shown that 96 (46.4%) of the isolates possessed the astA genetic determinant. The most common EAST1-positive E. coli serotype was O149:K91 and these strains were mostly LTI/STII-positive. A close correlation between the presence of F4 fimbriae and the EAST1 gene was also observed: 88 of 96 (91.7%) astA(+) isolates tested possessed the F4 antigen. Thus, EAST1 enterotoxin may represent an additional virulence determinant playing a role in the pathogenesis of porcine colibacillosis.  相似文献   

7.
A comprehensive study of 223 Escherichia coli isolates from pigs with colibacillosis included determination of O serogroups, detection of heat-labile enterotoxin, heat-stable enterotoxin (STa and STb), and identification of K88, K99, 987-P, F-41, and type 1 fimbriae. The incidence of the various E coli types among isolates of pigs of different ages was also determined. Escherichia coli bearing K88 fimbriae accounted for 48% of all isolates studied, were most often of serogroup O157, O149, or O8, and usually produced labile toxin alone or in combination with STa or STb. These E coli were commonly isolated from pigs in each age group studied (0 to 5 days, 6 to 10 days, 11 to 24 days, and greater than 24 days). Escherichia coli bearing 987-P accounted for 30% of the isolates, were most often of serogroup O141 or O20, and usually produced STa. Escherichia coli bearing K99 accounted for 13% of the isolates, usually were of serogroup O101 or O8, and almost always produced STa. Escherichia coli bearing 987-P or K99 were most often isolated from pigs less than 6 days of age. Fimbriae F-41, when identified, were usually on E coli of serotype O101:K99. Although infrequently found, type 1 fimbriae were on E coli of most of the serogroups identified in this study.  相似文献   

8.
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   

9.
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.  相似文献   

10.
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   

11.
Duplex real-time PCR assays were used as modules to cover partially automated detection of 12 genes encoding adhesins, enterotoxins and Shiga toxins in faecal E. coli isolates. For this a total of 194 E. coli isolates from pigs suffering from post-weaning diarrhoea (PWD), including 65 isolates with haemolytic activity, and 83 isolates from calves with diarrhoea were examined. Data obtained by PCR were compared with O-typing and with haemolytic activity as indirect virulence markers. E. coli O-types O139:K82, O141:K85, and O149:K91 accounted for 43.8% (n = 85) of all porcine strains and for 55.4% (n = 36) of the porcine strains, which exhibited haemolytic activity. These strains carried virulence genes by 65.9% (n = 56) and 80.6% (haemolytic E. coli, n = 29), respectively. The E. coli O-types O139:K82 and O141:K85 were significantly associated with the adhesin gene F18, and O149:K81 with the F4 gene. In this context, detection of the gene encoding F18 was coupled predominantly with the genes responsible for the production of the toxins ST-I, ST-II and Stx2, and the F4 gene with those of the enterotoxins ST-I, ST-II and LT. Both virulence patterns were detected more pronounced in E. coli strains with haemolytic activity. Fifty-six of a total of 83 E. coli isolates originating from calves were O-typed as O101 (O101:K28, O101:K30, O101:K32; n = 29), O78:K80 (n = 23), and O9:K35 (n = 4). Most of the E. coli O78:K80 strains carried the F17 gene (69.6%, n = 16). Virulence genes encoding for F4, F5 or ST-I were detected only in single cases. Intimin and Shiga toxin genes that are present in enterohaemorrhagic E. coli (EHEC) were not detected.  相似文献   

12.
为进一步完善中国大肠杆菌菌体微量凝集试验定型血清库，改良微量凝集试验用大肠杆菌O抗原定型血清的制备工艺，本试验选取大肠杆菌O50、O60、O117、O131血清型进行定型血清制备方法的探究。首先用大肠杆菌不同血清型的参考菌株制备灭活抗原，而后多次免疫家兔以采血获得粗血清，用微量凝集试验的方法确定不同粗血清的交叉凝集素及凝集效价，再通过交叉凝集素吸收法结合血清稀释法消除非特异性凝集，最终研制出特异性良好的微量凝集试验用大肠杆菌O抗原定型血清。本研究确定了大肠杆菌O50、O60、O117、O131定型粗血清的主要交叉凝集素，最终成功研制出特异性良好的微量凝集试验用大肠杆菌O50、O60、O117、O131定型血清共4种，凝集效价在1：256至1：2 048之间，其中微量凝集试验用大肠杆菌O50、O60定型血清无交叉凝集素，为单因子定型血清，微量凝集试验用大肠杆菌O117、O131定型血清存在1~2种非特异性的交叉凝集素O14和O107。本研究作为大肠杆菌O抗原定型血清制备工艺摸索过程中的重要部分，为完善中国大肠杆菌菌体微量凝集试验定型血清库，进一步改良微量凝集试验用大肠杆菌O抗原定型血清的制备方法提供了重要理论依据。  相似文献   

13.
DNA gene probes specific for genes encoding heat labile enterotoxin (LTI), heat stable enterotoxins (STIa, STII), vero cytotoxins (VT1, VT2), and adhesins K88 (F4), K99(F5), F41 and 987P(F6) were used to examine 873 isolates of E. coli from cases of diarrhoea (680 from pigs, 187 from cattle and six from sheep). A total of 188 were toxin gene positive and of these 84 belonged to the classical ETEC serogroups. Of the other 104 toxin gene positive strains, 80 hybridized with the VT2 probe of which 34 were from cases of porcine post-weaning diarrhoea belonging to serogroup 0138:K81 and 22 were untypable strains from cattle.  相似文献   

14.
【目的】探究荣昌、大足和隆昌三地鸭大肠杆菌分离株的O抗原、毒力基因及耐药性。【方法】将2014年—2021年鸭病料中分离得到的107株细菌在无菌条件下接种于麦康凯培养基中划线进行培养纯化,通过16S rDNA基因扩增测序和生化试验进行细菌鉴定,采用PCR技术对O抗原和16种毒力基因进行检测,采用Kirby-Bauer纸片扩散法进行药敏试验。【结果】107株分离株鉴定为大肠杆菌;O抗原鉴定试验鉴定出9种O抗原,其中优势抗原为O78(37.00%)、O7(25.00%),O121和O145(均为15.00%),并检测到5株O78+O145和O7+O145融合株;共检测出11种毒力因子,其中强致病性毒力基因有Tsh基因(检出率为25.23%)、fyuA基因(检出率为31.78%)、estB基因(检出率为31.78%)、Vat基因(检出率为2.80%)、iucA基因(检出率为44.56%)。3种毒力基因ompA、yijP和ibeB的携带率最高,分别为100.00%、96.26%和85.98%;药敏试验结果表明分离株对氨基糖苷类药物、米诺环素和多黏菌素最为敏感,对大环内酯类药物和克林霉素耐药,分...  相似文献   

15.
Enterotoxigenic and verotoxigenic F18+ Escherichia coli colonising the pig small intestine, adhere to receptors on intestinal villous enterocytes by F18 fimbriae. The aim of the present study was to define the F18R nature. The knowledge on the nature of this receptor could be important for the development of receptor-based treatments against F18+ E. coli-induced disease. The adhesion of F18+ E. coli to pig intestinal villous enterocytes was analysed in an in vitro assay. The adhesion of F18+ E. coli but not of F4ac+ E. coli was strongly inhibited by monoclonal antibodies (mAb) with blood group H-2 specificity. Conversely, blood group H-1 specific mAb could not inhibit the adhesion of F18+ E. coli nor F4ac+ E. coli. Moreover, the blood group H-2 trisaccharide strongly inhibited the adhesion of F18+ E. coli, but only partially the adhesion of F4ac+ E. coli. These data demonstrate that the F18 receptor contains the blood group antigen H-2 (-fuc-(1-2)-β-Gal-(1-4)-GlcNAc) as major carbohydrate.  相似文献   

16.
Five month old dogs from a Midwestern research kennel occasionally developed bloody diarrhea after shipment to other facilities. As previous diagnostic efforts failed to reveal any potential pathogens in feces from normal and diarrheic dogs, Escherichia coli was investigated for select virulence properties that may contribute to the occurrence of bloody diarrhea. Fecal swabs from 52 healthy dogs were examined for E. coli. Two hundred and sixty E. coli-like colonies were screened by PCR for the attaching and effacing (eae) gene, Shiga toxin (stx) genes, and the heat-stable enterotoxin type A (sta) gene. One hundred forty two of the 260 E. coli-like colonies (54.6%) from 43 dogs were eae or sta positive; and 60 of the eae and/or sta positive isolates were examined further. Among the 60 isolates, 23 (38.3%) possessed the eae gene, 32 (53.3%) possessed the sta gene, and five (8.3%) possessed both eae and sta genes (eae+/sta+). Of the 60 isolates, six sta+ and one eae+/sta+ isolates were hemolytic. When examined in the suckling mouse assay, five of six sta+ isolates and three of four eae+/sta+ isolates gave gut-to-remaining carcass ratios ≥0.083, indicating expression of heat-stable enterotoxin. These enterotoxin-producing isolates belonged to serogroups O42, O170, and O-negative.  相似文献   

17.
Two hundred and fifty Escherichia coli isolates from diarrhoeic and healthy piglets were serotyped and tested for the presence of virulence genes for fimbriae, intimin, heat-labile (LT) and heat-stable (STa and STb) enterotoxins, Stx toxins, and enteroaggregative heat-stable 1 (EAST1) enterotoxin by polymerase chain reaction (PCR). Although 220 isolates from diarrhoeic piglets belonged to 43 O serogroups and 77 O:H serotypes, 60% were of one of the 10 serogroups O2, O8, O15, O54, O84, O101, O141, O147, O149 and O157, and 60% belonged to only 10 serotypes (O8:H-, O54:H-, O84:H7, O101:H-, O141:H-, O141:H4, O147:H-, O149:H10, O163:H-, and ONT:H-). PCR showed that 79% of 220 isolates carried genes for at least one of the virulence factors tested. The gene encoding for EAST1 was the most prevalent (65%) followed by those encoding for STb (49%), LT (42%), STa (13%), and Stx2e (4%). Eighty-three (38%) of the 220 E. coli isolates carried the gene for F4 (K88), whereas genes for F18, F5 (K99), F41, F6 (P987), F17, and intimin (eae) were detected in 9%, 3%, 3%, 3%, 1%, and 3%, respectively. Seropathotype O149:H10:F4:LT/STb/EAST1 (70 isolates) was the most common, representing 32% of isolates. Pulsed-field gel electrophoresis (PFGE) analysis with XbaI of 15 O149:H10 representative isolates from diarrhoeic piglets distinguished 14 types. The 15 isolates exhibited a wide variability of distinct restriction patterns though all belonged to the same serotype (O149:H10), and all but one showed identical virulence determinants (F4, LT, STb, and EAST1). Among 30 isolates from healthy piglets only two virulence genes were detected: EAST1 (26%) and eae (17%). In total, 12 isolates were positives for the eae gene: five isolates had intimin beta1, four possessed intimin theta and three showed intimin type xiB. This is believed to be the first study describing the presence of intimin type xiB in E. coli of porcine origin.  相似文献   

18.
Twenty four, 21-d-old female pigs were fed diets containing either skim milk powder (CON+), spray-dried bovine colostrum (7.5%, BC+) or spray-dried bovine plasma (7.5%, BP+) and were dosed orally with 1 × 109 CFU of E. coli O149:K88. Another group of 8 unchallenged pigs was fed the skim milk powder diet (CON−). On d 19 of the experiment all piglets were euthanased. Adverse effects of the E. coli challenge were observed variously throughout the small intestine in pigs consuming either the BC+ or BP+ diets. In this experiment, similar responses to the E. coli challenge were observed in both plasma and colostrum fed pigs, which suggests that spray-dried bovine colostrum may be a potential alternative to spray-dried bovine plasma.  相似文献   

19.
【目的】筛选腹泻仔猪中携毒力基因且多重耐药的大肠杆菌菌株,评估中药水提物对该菌株的抑菌活性,并探索中药抑菌机制。【方法】通过PCR方法与Kirby-Bauer(K-B)药敏纸片法评估临床大肠杆菌菌株的肠毒素基因携带情况和耐药性;通过微量肉汤稀释法评估中药水提物对多重耐药大肠杆菌菌株的抑菌活性,确定最小抑菌浓度(minimal inhibitory concentration, MIC)和最小杀菌浓度(minimal bactericidal concentration, MBC);通过电导率仪以及相关试剂盒检测评估石榴皮水提物对多重耐药菌株作用不同时间后菌液电导率、碱性磷酸酶(alkaline phosphatase, AKP)含量及菌体内ATP含量的变化;通过SDS-PAGE和蛋白含量检测评估菌体内可溶性蛋白的含量变化;通过扫描电镜观察大肠杆菌形态变化。【结果】PCR检测14株临床大肠杆菌中肠毒素基因携带率达到78.57%,抗生素药敏试验结果显示,所有菌株至少对2种抗生素耐药,均属于多重耐药菌株。中药药敏试验结果显示,黄连、黄芩、石榴皮水提物对多重耐药菌株抑菌活性较好,其中石榴皮水提...  相似文献   

20.
This study was undertaken to determine the present distribution of serogroups, hemolytic activity and virulence factors among Escherichia coli strains isolated from pigs with postweaning diarrhoea from eight provinces in eastern China. Two hundred and fifteen E. coli isolates were serogrouped with O-antisera, investigated for hemolytic activity, assessed for F4, F5, F6, F18 and F41 fimbrial antigens by monoclonal antibodies and detected for genes of enterotoxins and shiga-toxin-two-variant (Stx2e) by a multiplex polymerase chain reaction (PCR). Among these E. coli isolates, 140 were determined to be placed in serogroups, 52 were unable to be serogrouped and the rest 23 auto-agglutinated. These isolates distributed in 45 serogroups and 64.3% (90/140) belonged to 12 O serogroups: O8, O9, O11, O20, O32, O91, O93, O101, O107, O115, O116 and O131. Hemolytic activity was detected in 11.6% (25/215) of all isolates. Several uncommon O serogroups were discovered in this study. Agglutination tests showed that 50.2% (108/215) of these isolates were positive for one or more of the five fimbrial antigens. Seventy-two E. coli strains expressed single fimbria and 36 strains expressed two or more fimbriae. Among these 215 E. coli isolates, strains expressing F18, F4, F6, F6 + F18 or F5 + F41 occurred more frequently. PCR analysis showed that 60.5% (130/215) of the isolates only harboured the gene of estI (STI) while 6.0% (13/215) strains possessed the genes of stx2e, estI and estII and 5.6% (12/215) of strains had the genes of estI/estII. Of all these isolates, 107 (49.8%) were negative for the fimbrial antigens examined. The fimbria-negative isolates usually possessed genetic determinant of estI (78, 72.9%).  相似文献   

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