人工感染犬埃立克体病的病理学观察

用常规病理学方法,对5只人工感染埃立克体（Ehrlichia)的比格犬进行病理解剖学和病理组织学观察。眼观所见最显著的病变是主要器官和皮下出血、淤血,脾、肝肿胀;病理组织学变化的主要特征是肝、肺和肾的血管内及肝血管周围存在浆细胞和淋巴细胞灶性增生。     

比格犬埃立克体病病理学研究

为了观察比格犬埃立克体病的病理学变化,用常规病理学方法,对6只人工感染埃立克体(Ehrlichia)的比格犬进行病理解剖学和病理组织学观察。结果:眼观所见最显著的病变是主要器官和皮下出血、淤血,脾、肝肿胀;病理组织学变化的主要特征是淋巴结的严重水肿,脾、肝、肺和肾的血管内及肝血管周围存在浆细胞和淋巴细胞灶性增生,皮肤表皮层变薄、皮肤皮脂腺腺泡上皮和毛囊变性坏死。比格犬埃立克体病的眼观和病理组织学变化与国外文献报道的基本吻合,不同之处是眼观病变更为明显,这可能与分离株的致病性不同有关。     

比格犬埃立克体病实验模型的建立

为犬埃立克体病的病理学、临床学、病原学的深入研究,我们用Beagle(比格犬）复制犬埃立克体病以建立犬埃立克体病实验模型。比格犬静脉接种E.platy和E.canis后,利用PCR和电镜技术确证感染成功。进一步的观察发现,接种后比格犬与最最感的德国牧羊犬自然感染埃立克体病的临床症关放病理学变化基本吻合。结果说明通过静脉接种病原成功建立了比格犬埃立克体病实验模型。     

比格犬埃立克体病实验模型研究Ⅲ病原观察

为了观察犬埃立克体病病犬血细胞中病原的感染情况,对6只人工感染埃立克体的比格犬血细胞进行了光镜和透射电镜观察.结果发现,单核细胞的细胞质和血小板中均存在埃立克体包涵体,其中单核细胞的包涵体内病原多达8个,血小板的包涵体内也发现数个病原.这一结果进一步证实我们成功地建立了比格犬埃立克体病实验模型,也为临床上诊断犬埃立克体病提供了形态学依据.     

比格犬埃立克体病试验观察及盐酸强力霉素治疗研究

作者研究了比格犬埃立克体病试验模型及盐酸强力霉素对犬埃立克体病的疗效。 结果表明,临床症状表现为急性发热、皮肤表面出现瘀血斑点,个别犬出现血便和血尿;姬姆萨染色血液涂片可见白细胞数稀少,单核细胞内有病原包涵体;血常规检查可见发病急性期血红蛋白含量和白细胞数较接种前相比显著减少;血液生化检测发现谷草转氨酶和谷丙转氨酶较接种前明显升高,而白蛋白明显降低;病理组织学观察发现淋巴结、脾脏、肝脏病变最为显著;试验再次证实强力霉素对犬埃立克体病的疗效是确定的。     

我国犬埃立克体病研究现状

犬埃立克体病是由严格细胞内寄生的埃立克体所致的疾病。目前,我国已经发现的犬埃立克体病原有犬埃立克体(Ehrlichia)和扁平埃立克体(E.platy)两种。我国已发现的犬埃立克体病均为E.canis和E.platy的混合感染。临床症状包括发热、体重严重减轻、流鼻血和腹泻带血等;白细胞和血小板计数同时下降是我国犬埃立克体病的特点;严重的病犬常因广泛性出血或继发感染而死亡。犬埃立克体病的病原学诊断主要依靠镜检、血清学试验和PCR等。犬血清埃立克体抗体的调查结果表明,我国犬埃立克体病的流行与蜱活动密切相关。四环素类抗生素是治疗犬埃立克体病的有效药物。     

比格犬埃立克体病实验模型研究Ⅰ.血常规及血生化检测

为观察犬埃立克体病急性期血液学变化,对6只人工感染埃立克体的比格犬进行了血常规及血生化检测.采集比格犬感染前后的血液样本,测定血常规及各项血生化指标,并对测定结果作统计学处理.血常规检测发现感染后RBC、WBC、HGB、HCT、PLT、MPV、LYM和MONO值极显著降低(P＜0.01),RDW显著降低(P＜0.05);血生化检测发现感染后ALT和AST极显著升高(P＜0.01),ALB极显著降低(P＜0.01).结果表明,我国犬埃立克体病急性期血液学变化较国外报道的更为明显,这可能与埃立克体中国病原株的致病性不同有关.     

犬在埃立克体病研究中的作用

随着新病原及病原新的致病性不断被发现 ,埃立克体及埃立克体病已经成为预防医学和兽医学研究热点。在已经发现的 1 1种埃立克体病原中 ,有 5种可以直接感染犬 ,引起不同的犬埃立克体病 ;另外 2种为早先分别从人单核细胞埃立克体病和粒细胞埃立克体病患者中分离的病原 ,在流行区的犬体内也可以分离到。资料表明犬对许多埃立克体都极为敏感 ,犬在埃立克体及埃立克体病研究上占有重要地位。鉴于这是我国近年才发现的新病原 ,许多兽医及研究工作者不认识它 ,文章就相关埃立克体对犬的感染和所致疾病以及在流行病学上的意义进行了综述。     

我国某养犬基地发现犬埃立克体病

从１９９８年４月起广州市郊某养犬基地发生犬流行病,其主要症状为发热、流鼻血、贫血和白细胞数减少。经动物感染和ＰＣＲ检测,证实病原为埃立克体属微生物。四环素对该病治疗有效。     

Monitoring C-reactive Protein in Beagle Dogs Experimentally Inoculated with Ehrlichia canis

The concentrations of C-reactive proteins (CRP) in the plasma of five beagle dogs experimentally inoculated with Ehrlichia canis increased markedly. The concentrations began to increase between 4 and 16 days and peaked between 15 and 42 days after inoculation of E. canis. The peak concentrations ranged from 217.8 to 788.8 g/ml (452.6±228.1 SD). After the peak, the concentrations of CRP decreased rapidly. The PCR product of 16S rRNA of E. canis became detectable in the five dogs between 18 and 27 days after inoculation of E. canis. Antibodies to E. canis were detected in plasma from the dogs between 5 and 15 days after inoculation of E. canis. The timings of seroconversion and of the start of the increase in CRP were approximately similar and the high concentrations of CRP in the plasma of the dogs tended to become apparent when the PCR product of 16 S rRNA of E. canis became detectable.     

广州地区犬场工作人员与一般人群犬埃立克体感染的比较研究

从比格犬埃立克体阳性血清中提取犬埃立克体IgG,用此IgG免疫鸡制备出抗抗体,用已建立的ELISA检测法对采集的人血清样本进行检测。143份随机采集的人血清4份呈阳性,阳性率2.78%;52份犬场工作人员血清6份呈阳性,阳性率11.54%。结果表明,广州地区犬场工作人员较一般人群犬埃立克体感染率高。     

Prevalence of Ehrlichia canis, Anaplasma platys, Babesia canis vogeli, Hepatozoon canis, Bartonella vinsonii berkhoffii, and Rickettsia spp. in dogs from Grenada

To identify the tick-borne pathogens in dogs from Grenada, we conducted a serologic survey for Ehrlichia canis in 2004 (104 dogs) and a comprehensive serologic and molecular survey for a variety of tick-borne pathogens in 2006 (73 dogs). In 2004 and 2006, 44 and 32 dogs (42.3% and 43.8%) were seropositive for E. canis, respectively. In 2006, several tick-borne pathogens were identified by serology and PCR. DNA of E. canis, Anaplasma platys, Babesia canis vogeli, Hepatozoon canis, and Bartonella sp. were identified in 18 (24.7%), 14 (19.2%), 5 (7%), 5 (7%), and 1 (1.4%) dogs, respectively. Six (8.2%) dogs were seropositive for Bartonella vinsonii subsp. berkhoffii. All dogs were seronegative and PCR-negative for Rickettsia spp. Coinfection with two or three pathogens was observed in eight dogs. Partial 16S rRNA E. canis and A. platys sequences were identical to sequences in GenBank. Partial 18S rRNA gene sequences from the Grenadian H. canis were identical to each other and had one possible mismatch (ambiguous base) from H. canis detected from Spain and Brazil. Grenadian B. c. vogeli sequences were identical to B. c. vogeli from Brazil and Japan. All of the detected pathogens are transmitted, or suspected to be transmitted, by Rhipicephalus sanguineus. Results of this study indicate that dogs from Grenada are infected with multiple tick-borne pathogens; therefore, tick-borne diseases should be included as differentials for dogs exhibiting thrombocytopenia, leukopenia, fever, or lethargy. One pathogen, E. canis, is also of potential public health significance.     

Cultivation and molecular identification of Ehrlichia canis and Ehrlichia chaffeensis from a naturally co-infected dog in Venezuela

Background: Diagnosis of canine ehrlichiosis in Venezuela is normally performed by examination of buffy coat smears (BCS). Characteristic inclusion bodies are frequently observed in leukocytes and platelets from dogs with clinical signs of the disease. Objective: The purpose of this study was to investigate the co-infection of a dog with Ehrlichia canis and E hrlichia chaffeensis using microbiological and molecular techniques. Methods: Primary cultures of monocytes from a dog showing signs of ehrlichiosis were performed. Ehrlichial inclusions in blood cells were demonstrated by BCS and in cultured cell smears with direct immunofluorescence and Dip Quick staining. Nested PCR analysis was performed with DNA from blood samples and cultures, using primers specific for E. canis and E. chaffeensis. The amplified DNA fragments were sequenced to confirm the specificity of the amplifications. Results: The BCS of the naturally infected dog contained intracellular morulae. Ehrlichial inclusions were observed 9 days after inoculation of the primary cultures. After 3 passages with monocytes from a healthy dog, 65% of infected cells, and cells with >60 morulae were observed. A healthy female German Shepherd dog, seronegative for E. canis and E. chaffeensis antigens and without contact to ticks, was inoculated with an infected culture. The animal developed signs of canine monocytic ehrlichiosis and became seropositive. Nested PCR results and sequencing of amplified DNA fragments demonstrated the simultaneous presence of E. canis and E. chaffeensis in both dogs. Conclusions: This is the first report of E. chaffeensis in dogs in South America. This organism was previously identified in dogs by PCR only in the United States.     

The Pharmacokinetics of a Long-acting Oxytetracycline Formulation in Healthy Dogs and in Dogs Infected with Ehrlichia canis

The pharmacokinetic properties of oxytetracycline were studied following a single injection of a long-acting formulation (20 mg/kg body weight) into the semimembranosus muscle of healthy dogs and of dogs that had been experimentally infected with Ehrlichia canis. The disposition curves of the long-acting oxytetracycline formulation before and after infection were best described by a bi-exponential decline after a first-order absorption. The mean maximum serum concentration (C _max) following infection was significantly lower and the time taken to attain this concentration (t _max) was significantly shorter than that in the healthy dogs. The mean apparent elimination half-life (t _1/2) was significantly increased following infection. The corresponding rate constant () was significantly decreased. The absorption half-life (t _1/2ab) was significantly decreased after infection. The volume of distribution at steady state (V _dss) increased significantly following infection. It was concluded that the pharmacokinetic behaviour of a long-acting oxytetracycline in dogs after intramuscular administration is characterized by a two-compartment model with a slow elimination phase. This could be due to flip-flop kinetics. The febrile reaction in experimental E. canis infection affected some pharmacokinetic parameters of oxytetracycline.     

新疆部分地区临床型乳房炎源大肠杆菌的调查分析

为了研究新疆部分地区临床型乳房炎源大肠杆菌的感染率、耐药情况及致病情况,采集47份临床型乳房炎乳样进行大肠杆菌分离鉴定,并开展了药敏试验、毒力基因检测及小鼠攻毒试验.结果分离到14株大肠杆菌,分离率为29.79％(14/47).11种抗生素药敏试验显示,对头孢哌酮+头孢曲松+红霉素+庆大霉素+强力霉素+恩诺沙星+氯霉素...     

Humoral Antibody Responses of Swine Infected Experimentally with Group E Streptococcus II. Antistreptokinase and Antistreptodornase Responses

Swine infected experimentally with group E Streptococcus (GES) produced significant antibody titers against streptokinase (streptococcal fibrinolysin, SK) and streptodornase (streptococcal deoxyribonuclease, SD). The antibodies directed against SK (antistreptokinase, ASK) appeared two to nine weeks postexposure and persisted for the duration of the experiment (nearly six months). The ASK inhibited SK produced by GES antigenic types III, IV, and V, by GES devoid of type specific antigen, and by a group P Streptococcus. Selected strains of GES serotypes I and II and group U Streptococcus did not produce detectable SK.

The antibodies directed against SD (antistreptodornase, ASD) appeared two to three weeks postexposure, reached a peak about six weeks postexposure, and persisted at high levels for nearly six months (the duration of the experiment). The ASD inhibited SD produced by all known antigenic types of GES, by GES devoid of type specific antigen, and by strains of groups P and U Streptococcus. The antibodies failed to inhibit SD produced by group C Streptococcus.

The potential utilization of ASK and ASD titers as serological means of identifying swine infected with GES (carrier swine) is discussed.

     

Investigation of renal protein loss in dogs with acute experimentally induced Ehrlichia canis infection.

Urinary protein-to-creatinine ratios and serum albumin concentrations were measured in 8 adult male dogs experimentally inoculated with Ehrlichia canis. Urinary protein concentration increased significantly, but transiently, during the acute phase of infection. Urinary protein-to-creatinine ratios were highest (mean, 8.6) during the third and fourth weeks after infection, and decreased to less than 0.5 by 6 weeks after infection. Correspondingly, albumin concentration decreased significantly during the acute phase. Serum albumin concentrations were lowest (mean, 2.1 g/dl) the fourth week after infection and increased to greater than 3.0 g/dl by 11 weeks after infection. There was an inverse linear correlation between urinary protein-to-creatinine ratio and serum albumin concentration. The magnitude of proteinuria and its inverse relationship with serum albumin concentration suggested that hypoalbuminemia associated with acute E canis infection may be attributable primarily to increased renal loss of protein, rather than decreased hepatic synthesis as previously suggested. Another dog was subsequently inoculated with E canis from 1 of the experimentally infected dogs and a renal biopsy was performed during peak proteinuria (urinary protein-to-creatinine ratio = 22 and serum albumin = 1.1 g/dl). Immunofluorescent staining revealed mild to moderate deposits of anti-canine IgM, and to a lesser extent, anti-canine IgG and complement factor C3 in the glomerular tufts and mesangium. Ultrastructural evaluation revealed distortion and fusion of podocyte foot processes and increased microvilli on podocytes. These morphologic changes were consistent with transient glomerular leakage of protein of a magnitude that would significantly contribute to hypoalbuminemia during acute E canis infection. An underlying immunologic mechanism was suggested by positive glomerular immunofluorescence and previously described histologic findings.     

临床型乳房炎奶牛致病性大肠杆菌血清型研究

为有效防治乳房炎以及进一步研究致病性大肠杆菌的危害性,本研究对呼和浩特市某奶牛场16头患临床型乳房炎的奶牛进行采样分析了致病性大肠杆菌。结果表明,在16份粪样、乳样中致病性大肠杆菌的检出率分别为100%和68.75%,血样中未检出致病性大肠杆菌。经动物试验表明,所检出的致病菌均有强致病力。在血清型鉴定中,粪样中分离鉴定出致病性大肠杆菌为O51、O55、O127、O7、O91、O101、O112、O92、O142血清型较多;乳样中分离出的致病性大肠杆菌为O55、O101、O112、O134、O51、O53、O78、O91、O126、O128、O158血清型较多。且粪样中分离出的致病性大肠杆菌42种血清型,乳样中分离出的致病性大肠杆菌33种血清型中具有25种血清型相同,分别为:O8、O35、O44、O51、O55、O61、O62、O65、O69、O80、O91、O92、O95、O96、O98、O99、O100、O101、O112、O120、O127、O134、O142、O153、O158。因此可见,作为环境性病原菌,大肠杆菌侵入乳房而引发了奶牛乳房炎。