禽大肠杆菌病的诊治

禽大肠杆菌病是由致病性大肠杆菌引起各种禽类的急性或慢性的细菌性传染病。介绍了禽大肠杆菌病的流行病学、临床症状、病理变化、诊断与防治,以期为防治禽大肠杆菌病提供参考。     

禽大肠杆菌病的诊治

禽大肠杆菌病是由致病性大肠杆菌引起各种禽类的急性或慢性的细菌性传染病。介绍了禽大肠杆菌病的流行病学、临床症状、病理变化、诊断与防治,以期为防治禽大肠杆菌病提供参考。     

浅析规模化养殖场鸡源致病性大肠埃希菌的防控

正禽大肠杆菌病是由不同血清型的禽致病性大肠杆菌引起的严重危害世界养禽业健康发展的重要细菌性传染病之一,可引起如败血症、慢性呼吸道疾病、卵黄感染、脐炎、气囊炎、肝周炎、心包炎等慢性或急性禽病或更严重。大肠杆菌血清型众多,只有部分大肠杆菌具有致病性,常见的禽致病性大肠杆菌血清型为O_1、O_2、O_(78)。中国的东北地区大肠杆菌血清型种类最多,华中地区的绝对优势血清型最为典型。本文笔者主要总结比较了     

山东省鸡致病性大肠杆菌的分离鉴定

<正>鸡的大肠杆菌病是由某些血清型的大肠杆菌引起的一类疾病,随着养鸡业的集约化发展,该病的传播越来越严重,对养鸡业造成的经济损失巨大。为明确本省致病性大肠杆菌的血清型、有针对性地研究预防和治疗鸡大肠杆菌病的药物和方法,对山东省鸡致病性大肠杆菌进行了分离和鉴定。1材料与方法1.1病料及分型血清病料采自山东省德州市兽医站禽病门诊、淄博市兽医站禽病门诊、沂水县兽医站禽病门诊,胶州市、莱州市、临朐县等多个肉鸡     

禽致病性大肠杆菌的分离鉴定及致病性研究

禽大肠杆菌病是由禽致病性大肠杆菌所引起的严重危害养禽业健康发展的重要细菌性传染病之一。本试验对寿光市某养殖场送检的具有典型大肠杆菌病的临床症状的15只病死鸡进行剖检,病理组织学观察,分离鉴定出禽致病性大肠杆菌;并用分离纯化的细菌对7日龄的雏鸡进行注射,连续观察7d,研究其致病性及感染雏鸡发病特点,同时对死亡雏鸡进行了系统的病理组织学观察,分析了大肠杆菌感染雏鸡的致病规律。为临床上雏鸡大肠杆菌病的诊断和防治提供理论依据。     

禽大肠杆菌病的诊断和中药防治方剂应用

禽大肠杆菌病是指由致病性的大肠杆菌所引起的各种禽类的急性、慢性传染病。在此之所以讲致病性,原因是到目前为止,已发现大肠杆菌血清型很多,仅鸡种已达50种,包括鸭、鹅及珍特禽血清型则更多。鸡大肠杆菌病致病能力很强,传播快而广,20世纪80年代后除新城疫、马立克氏病、鸭瘟、小鹅瘟外,禽大肠杆菌病已上升为主要传染病之一。但现在已有行之有效疫苗可用于预防。     

禽大肠杆菌毒力因子的研究进展

禽致病性大肠杆菌是毒力基因的贮存宿主,多种毒力因子的协同作用使其产生致病性,而耐药性的产生加大了对其防治的难度。本文主要对禽大肠杆菌毒力因子的种类、毒力特性及分子流行病学等研究进展进行了概述,为深入研究禽大肠杆菌病的致病机理和制定防控措施提供理论依据。     

圈养野生禽类致病性大肠杆菌的防治措施

禽致病性大肠杆菌(APEC)作为一种肠道外致病性大肠杆菌,引起的包括鸡、火鸡在内的各种禽类的急或慢性传染病统称为禽大肠杆菌病,其临床症状主要包括大场杆菌性肉芽肿、大肠杆菌性败血症、眼炎、心包炎、气囊炎和滑膜炎等,也是一种重要的禽类主要的细菌传染病病原,具有重要的公共卫生学意义。因此,开展圈养野生禽类致病性大肠杆菌的流行病学调查与监测,对于该病的防治具有非常重要的理论参考和现实意义。本研究旨在介绍圈养野生禽类致病性大肠杆菌的流行特点和防治措施,为圈养野生禽大肠杆菌病的防治提供科学依据。     

禽大肠杆菌病常见临床病型与综合防治

禽大肠杆菌病是由大肠埃氏菌的某些致病性血清型菌株引起的疾病总称。最近几年来在山东各地流行特别严重,今就其流行特点、临床常见病型和综合防治措施阐述如下。一、禽大肠杆菌病的流行特点1.禽大肠杆菌病的传染源。大肠     

水禽大肠杆菌病病原的分离与血清型鉴定

禽大肠杆菌病是由多种致病血清型或条件致病性大肠杆菌引起的不同类型禽病的总称。随着饲养数量与密度的不断增大,水禽大肠杆菌病已成为常发病之一,同时经常出现使用抗菌药物防治及免     

鸡致病性大肠埃希菌素V质粒研究进展

大肠埃希菌素V(ColV)质粒是鸡致病性大肠埃希菌中重要的毒力质粒之一,能够编码大肠埃希菌素V、血清抗性、铁摄取系统等与致病相关的毒力基因。目前虽然对鸡的大肠埃希菌病研究的比较广泛,但其确切的发病机制仍需继续深入研究。文章综述了ColV质粒与鸡大肠埃希菌病的联系,及其3个表型与鸡致病性大肠埃希菌毒力的关系,为防控鸡大肠埃希菌病提供新的思路。     

禽大肠杆菌病疫苗研究进展

禽致病性大肠杆菌(APEC)是引起家禽多种肠外疾病如气囊炎、心包炎、肝周炎、蜂窝织炎及败血症的主要人畜共患病原菌.在过去的数十年间,试验了多种不同类型的疫苗用于本病的控制.鉴于APEC血清型较多且不同血清型之间缺乏交叉免疫保护,故生产上使用的APEC疫苗研究进展缓慢.作者对不同类型APEC疫苗进行了综述并提出未来的研究方向.     

鸡源致病性大肠埃希菌菌毛基因研究进展

菌毛是鸡大肠埃希菌的重要致病因子之一。文章对鸡源致病性大肠埃希菌菌毛的特点及分类,各型菌毛亚单位基因结构及其功能与控制,鸡源致病性与其他动物源大肠埃希菌菌毛之间的同源性进行了综述。这对了解菌毛亚单位基因结构与致病力的关系,探讨鸡源大肠埃希菌的致病力与分布有重要意义。     

Emerging avian pathogenic Escherichia coli strains belonging to clonal groups O111:H4-D-ST2085 and O111:H4-D-ST117 with high virulence-gene content and zoonotic potential

The present study characterizes, for the first time, two emerging avian pathogenic Escherichia coli (APEC) clonal groups of serogroup O111: O111:H4-D-ST117 and O111:H4-D-ST2085. The clonal group O111:H4-D-ST117 was already present in APEC strains isolated between 1991 and 2000, and was still present in strains isolated between 2004 and 2009, showing long time evolution according to the virulence-gene differences and macrorestriction profiles. Among ST117 strains, two virulence profiles could be distinguished: papG II-positive tsh-negative strains which satisfied criteria for extraintestinal pathogenic E. coli (ExPEC), and papG II-negative tsh-positive strains without ExPEC status. Interestingly, we have detected a human septicemic O111:H4-D-ST117 ExPEC strain isolated from a hemocultive in 2000 whose macrorestriction profile showed >85% similarity with four APEC strains of the study. The clonal group O111:H4-D-ST2085 was exclusively detected in 17 APEC strains isolated in 2008 and 2009, and showed short time evolution based on its homogeneity since all were nalidixic acid-resistant, all had ExPEC status, and most carried papG II and tsh genes. From the clinical point of view, O111:H4-D-ST2085 seems a successful clonal group that could be the result of the epidemiological evolution of O111:H4-D-ST117. Due to the increasing prevalence of both clonal groups among clinical APEC isolates, their high virulence-gene content, and zoonotic potential, we suggest them as possible candidates for the development of a future vaccine against avian colibacillosis.     

Immune response to recombinant Escherichia coli Iss protein in poultry

Colibacillosis accounts for significant losses to the poultry industry, and control efforts are hampered by limited understanding of the mechanisms used by avian pathogenic Escherichia coli (APEC) to cause disease. We have found that the presence of the increased serum survival gene (iss) is strongly associated with APEC but not with commensal E. coli, making iss, and the protein it encodes (Iss), candidate targets of colibacillosis control procedures. To assess the potential of Iss to elicit a protective response in chickens against APEC challenge, Iss fusion proteins were produced and administered subcutaneously to four groups of 2-wk-old specific-pathogen-free leghorn chickens. At 4 wk postimmunization, birds were challenged with APEC from serogroups 02 and 078 via intramuscular injection. At 2 wk postchallenge, birds were necropsied, and lesions consistent with colibacillosis were scored. Also, sera were collected from the birds pre- and postimmunization, and antibody titers to Iss were determined. Immunized birds produced a humoral response to Iss, and they had significantly lower lesion scores than the unimmunized control birds following challenge with both APEC strains. Birds that received the smallest amount of immunogen had the lowest lesion scores. Although further study will be needed to confirm the value of Iss as an immunoprotective antigen, these preliminary data suggest that Iss may have the potential to elicit significant protection in birds against heterologous E. coli challenge.     

Avian pathogenic Escherichia coli (APEC)

Infections with avian pathogenic Escherichia coli (APEC) cause colibacillosis, an acute and mostly systemic disease resulting in significant economic losses in poultry industry worldwide. Avian colibacillosis is a complex syndrome characterized by multiple organ lesions with airsacculitis and associated pericarditis, perihepatitis and peritonitis being most typical. Environmental factors as well as the constitution of poultry or initial viral infections influence the outcome of APEC-infections. However, several challenge experiments in chickens proofed the role of virulent APEC strains as the single aetiological agent. Currently serotypes O1:K1, O2:K1 and O78:K80 are recognized as the most prevalent, however the number of published serotypes is increasing. In addition, single APEC isolates vary profoundly in virulence, and knowledge about the molecular basis of this variability is still scarce. Known virulence factors of APEC are adhesins (F1- and P-fimbriae), iron acquisition systems (aerobactin and yersiniabactin), hemolysins (hemolysinE and temperaturesensitive hemagglutinin), resistance to the bactericidal effects of serum and phagocytosis (outer membrane protein, iss protein, lipopolysaccharide, K/1)-capsule and colilcin production) as well as toxins and cytotoxins (heat stable toxin, cyto-/verotoxin and flagella toxin). Esperimental studies have shown that the respiratory tract, principally the gas-exchange region of the lung and the interstitium of the air sacs are the most important sites of entry for avian pathogenic E. coli. APEC strains adhere to the epithelial cells of air sacs presumably through F1-fimbriae. After colonization and multiplication the bacteria enter the bloodstream, and the temperature-sensitive hemagglutinin (tsh) seems to be important int his step. After invading the bloodstream APEC cause a septicemia resulting in massive lesins in multiple internal organs and in sudden death of the birds. The ability of the bacteria to acquire iron and the resistance to the bactericidal effects of serum, predominantly conferred by the increased serum survival (iss)--protein, enables APEC to multiply quickly in their hosts. Iss is regarded a specific genetic marker for avian pathogenic E. colistrains. A critical review of the literature published so far on APEC reveals, that these pathotypes are not defined appropriately. This findings urge investigations on the population structure of APEC, enabling the establishment of appropriate diagnostic tools and avoiding the obsolete use of serotyping for APEC diagnosis. So far more than 20 APEC strains have been investigated in animal experiments, explaining contrary published results. Thus, the lack of knowledge in pathogenicity and in immunity of APEC infections urges further experimental studies. As APEC share not only identical serotypes with human pathogens but also specific virulence factors, their zoonotic potential is under consideration.     

Virulence-associated genes and antimicrobial resistance among avian pathogenic Escherichia coli from colibacillosis affected broilers in Pakistan

Avian pathogenic Escherichia coli (APEC) causes colibacillosis that leads to high morbidity and mortality among poultry birds. To date, there is a lack of knowledge about virulence-associated genes (VAGs) and multidrug resistance of APEC isolates from Pakistan. In this study, we determined the VAGs and antibiotic resistance profiles of APEC isolates recovered from colibacillosis affected broilers in Faisalabad region of Pakistan. A total of 84 diseased and dead birds from different local broilers farms were collected and examined for the gross lesions of colibacillosis by conducting postmortem examination. Of these, APEC isolates were recovered from 75 (89.2%) birds. Antibiotic susceptibility tests against 11 antimicrobial agents showed the highest resistance against ampicillin (98.6%) followed by tetracycline (97.3%) and ciprofloxacin (72%). The presence of 11 virulence-associated genes (VAGs) was detected by multiplex polymerase chain reaction (PCR). Of the 75 APEC, 32 (42.6%) harbored > 5 VAGs. Most commonly found genes were increased serum survival (iss; 84%), iron transport (iutA; 74.6%), and colicin V (ColV; 60%). Twenty-two isolates (29.3%) were found to possess a combination of VAGs; iss, tsh, iroN, and iutA, in addition to other VAGs. To the best of our knowledge, this is the first report on the detection of virulence-associated genes and multidrug resistance among APEC isolates in Pakistan. In the future, the strains with the predominant set of VAGs can be used for colibacillosis diagnosis and as a potential vaccine candidate.

     

Clinical and microbial efficacy of antimicrobial treatments of experimental avian colibacillosis

The clinical and microbial efficacy of antimicrobial treatments of avian colibacillosis was studied, using an experimental model on chickens previously inoculated with multiresistant commensal Escherichia coli strains. One E. coli with pMG252 plasmid containing bla(FOX5) and qnrA1 genes and another E. coli with pMG298 plasmid containing bla(CTX-M15) and qnrB1 genes were first orally inoculated to chickens Both isolates were also resistant to chloramphenicol, sulphamethoxazole, trimethoprim, streptomycin, gentamicin, kanamycin, and tetracycline. The birds were then experimentally infected with an avian pathogenic E. coli (APEC), via the air sac. Treatments (oxytetracycline (OTC), trimethoprim-sulfadimethoxin (SXT), amoxicillin (AMX) or enrofloxacin (ENR) were then offered at the therapeutic doses. Symptoms, lesions in dead or sacrificed birds, and isolation and characterization of APEC from internal organs were studied. Results showed that OTC, SXT or ENR treatments could control the pathology. AMX worsened the disease, possibly due to endotoxin shock. All APEC re-isolated from internal organs showed the same antimicrobial susceptibility as the APEC inoculated strain, except for one APEC isolate from an infected OTC-treated bird, which acquired tetracycline resistance only, and one APEC isolate recovered from the air sacs of a chicken in the infected SXT-treated group, which acquired the pMG252 plasmid and became multi-resistant. Thus three antimicrobials could control the disease but the experimental model enabled, to our knowledge, the first observation of plasmid transfer from a bacterium of the intestinal tract to a pathogenic isolate from the respiratory tract.     

Virulence traits of avian pathogenic (APEC) and fecal (AFEC) <Emphasis Type="Italic">E. coli</Emphasis> isolated from broiler chickens in Algeria

Avian pathogenic E. coli (APEC) is the etiologic agent of avian colibacillosis, the most common disease responsible for chicken morbidity in the world. Although multiple virulence-associated factors were identified, their prevalence in Algeria is still poorly known. In the present research, 92 avian pathogenic E. coli (APEC) isolates were recovered from broilers with clinical signs and lesions of colibacillosis. In addition, 32 E. coli isolates collected from feces of healthy birds (AFEC) were included for comparison. All isolates were investigated by PCR for the presence of a total of 11 virulence-associated genes described for avian pathogenic (iroN, ompT, hlyF, iss, iutA, and fimC) and diarrheagenic E. coli (eae, stx, elt/est, ipaH, and aggR). The sensitivity of 39 APEC isolates to 16 antibiotics was also determined using antimicrobial pretreated microplates. Here, we report that 98% of the examined isolates host at least one of the tested virulence factors. The most prevalent genes in APEC were iutA (90.6%), ompT (86.9%), and iss (85.8%); whereas, iutA (78.1%), fimC (78.1%), and iroN (68.7%) were the highest prevalent genes in AFEC. Our data showed that none of the AFEC isolates harbor any of the tested diarrheagenic genes. Moreover, only elt/est (5.4%), stx (2.1%), and ipaH (2.1%) genes were carried by APEC isolates. We further established that ceftazodime, ceftiofur, mequindox, amoxicillin/clavulanic acid, and meropenem were the most efficient antibiotics against the analyzed APEC isolates. Overall, our findings provide more insights about APEC and AFEC virulence potential in Algeria which could participate in the fight against colibacillosis.     

Predominance of the papGII allele with high sequence homology to that of human isolates among avian pathogenic Escherichia coli (APEC)

Avian pathogenic Escherichia coli (APEC) are often found in poultry and are responsible for a set of diseases, commonly referred to as avian colibacillosis. One of the important virulence factors is adhesion to different epithelial surfaces, which is mediated by pili. P pili are thought to play a role by means of their PapG adhesin, which occurs in three molecular variants: PapGI, PapGII and PapGIII. This study is the first to determine and analyse the distribution of the different papG alleles in APEC. Our results show a significant predominance of the papGII allele above all other alleles or allele combinations. No statistically significant associations could be found between papG allele distribution and the type of bird, organ of isolation and O serogroup. Finally, the papGII and papGIII sequences showed high homology with mammalian (including human) source papG sequences.