疹块型猪丹毒宰后的感官鉴别诊断要点

疹块型猪丹毒出现的皮肤变化与某些因机械的、物理的、生物的、营养的以及过敏反应引起的皮肤变化有相似之处,因此在屠宰检验中要加以鉴别诊断。猪丹毒是宰后肉品卫生检验中最常见的传染病之一,因此了解和掌握该病宰后的一些特性,将会对进一步鉴别诊断起着有益的作用。猪疹块型     

猪丹毒丝菌灭活疫苗免疫佐剂的筛选

旨在筛选适宜于猪丹毒丝菌灭活疫苗的佐剂。以分离鉴定出的猪丹毒丝菌1a型HG-1株灭活菌体为抗原分别配制矿物油佐剂疫苗（简称矿物油疫苗）、氢氧化铝胶佐剂疫苗（简称铝胶疫苗）、ISA201双相油乳佐剂疫苗（简称ISA201疫苗）、GEL02水溶性聚合物佐剂疫苗（简称GEL疫苗）、IMS1313水溶性纳米佐剂疫苗（简称IMS1313疫苗）共5种佐剂的灭活疫苗。小鼠免疫保护试验结果表明,二免14 d后使用约为4 LD₅₀的HG-1株对小鼠进行腹腔攻毒,矿物油疫苗和GEL疫苗的保护率分别为100%（7/7）和71%（5/7）,其他三种佐剂疫苗的保护率均为14%（1/7）。本研究进一步选择铝胶疫苗和GEL疫苗进行猪体对比试验;仔猪安全性试验结果表明,两种佐剂疫苗的副反应均较小;免疫保护试验结果表明,两次免疫后使用约为16 LD₁₀₀的HG-1株对免疫仔猪进行耳缘静脉攻毒,两种佐剂疫苗的保护率分别为60%（3/5）和100%（5/5）。本研究最终选择GEL佐剂作为开发猪丹毒灭活疫苗的最适佐剂。     

猪丹毒疫苗效力检验攻毒冻干培养物的制备与应用研究

为提高猪丹毒疫苗效力检验结果的稳定性、一致性及工作效率,冻干制备了效力检验攻毒用猪丹毒丝菌培养物,对性状、纯粹、真空度、剩余水分、活菌计数、均一性等进行检测,测定在不同温度下短期存放的活菌数,监测在低温下长期保存的活菌数和毒力,并将其应用于猪丹毒活疫苗和灭活疫苗的效力检验。结果显示,该攻毒培养物性状良好,纯粹生长,真空度合格率98.2%,剩余水分小于3.5%,活菌数均值为3.8×10~9 CFU/瓶,瓶间活菌数变异系数(C.V)为10.0%,37℃以下温度存放2.5～3.0 h活菌数稳定,变异系数(C.V)为4.9%,-20℃保存36个月活菌数为3.0×10~9 CFU/瓶,每只小鼠注射6 CFU活菌5/5死亡,应用于猪丹毒灭活疫苗和活疫苗效力检验结果与常规方法一致。结果表明,该猪丹毒丝菌冻干培养物状态良好,活菌数和毒力较为稳定,能够满足猪丹毒疫苗效力检验攻毒使用,且提高了检验结果的一致性、稳定性及工作效率。     

Enzymatic profiles of Erysipelothrix rhusiopathiae and Erysipelothrix tonsillae

The enzymatic activities of 39 strains of Erysipelothrix rhusiopathiae and 34 of E tonsillae were determined with the API ZYM system. The profiles of these two species were very similar, differing solely in N-acetyl-beta-glucosaminidase activity. Whereas 90 per cent of strains of E rhusiopathiae exhibited strong activity with N-acetyl-beta-glucosaminidase, positive reactions were observed for this enzyme in only 24 per cent of strains of E tonsillae. These results support previous DNA-DNA hybridisation studies and suggest that E tonsillae is a new species of the genus Erysipelothrix.     

Antimicrobial Susceptibilities of Erysipelothrix rhusiopathiae Isolated from Pigs with Swine Erysipelas in Japan, 1988–1998

The susceptibility to 21 antimicrobial agents of 214 strains of Erysipelothrix rhusiopathiae isolated from pigs affected with swine erysipelas in Japan between 1988 and 1998 was determined. Ampicillin, cloxacillin, benzylpenicillin, ceftiofur, tylosin, enrofloxacin and danofloxacin were the most active agents [minimum inhibitory concentrations (MICs); ≤ 0.025?0.78 μg/ml], followed by cefazolin, virginiamycin, tiamulin, chloramphenicol, florphenicol and oxolinic acid (MICs; 0.1–25 μg/ml). Activity was poor or absent with kanamycin and sulfadimethoxine. Strains resistant to dihydrostreptomycin, erythromycin, clindamycin, lincomycin, oxytetracycline and doxycycline were detected. The susceptibilities to dihydrostreptomycin and oxytetracycline tended to decrease. Investigation of the differences in antimicrobial susceptibility of the 214 strains according to their serotypes, sources, isolation years and regions, showed that the strains resistant to dihydrostreptomycin were most frequently found in the strains of serotype 1a and in strains from septicaemic cases. Strains resistant to oxytetracycline were detected in all serotypes and all sources, and most of the strains resistant to erythromycin were detected in the strains of serotype 2. The frequency of strains resistant to dihydrostreptomycin gradually increased from 1988 to 1996, but then decreased between 1997 and 1998. The frequency of strains resistant to oxytetracycline was remained more than 38% from 1988 to 1998. It was suggested that the strains resistant to dihydrostreptomycin and oxytetracycline were distributed over almost all districts of Japan.     

Induction of cross-protection in mice against dolphin Erysipelothrix rhusiopathiae isolates with a swine commercial vaccine

Erysipelothrix rhusiopathiae is well known to cause disease in dolphins. This disease occurs either in an peracute way, leading to mortality even before clinical signs are observed or in a sub-acute way, characterized by rhomboidal skin lesions, that can be treated with penicillin or its derivatives. Commercial swine vaccines, containing inactivated serotype 2 strains, are currently used for vaccination but it is not known whether these vaccines induce protection against E. rhusiopathiae isolates from dolphins. In the present study, it was demonstrated in a mouse model that vaccination with a commercial swine vaccine (Eurovac Ery, Eurovet, Belgium) containing inactivated serotype 2 E. rhusiopathiae strains induced protection against challenge with three E. rhusiopathiae isolates from dolphins. The duration of the protection varied, depending on the challenging isolate, between 8 and >23 weeks. There was however no positive correlation between the amount of antibodies at the moment of challenge and the observed protection.In conclusion, vaccination trials in mice indicate that commercial serotype 2 swine Erysipelothrix vaccines induce protection against erysipelas caused by dolphin pathogenic isolates.     

Two new serotypes of Erysipelothrix rhusiopathiae.

Among a group of 16 argentine strains of Erysipelothrix rhusiopathiae 2 new serotypes have been found. Typing was performed by means of the agar gel diffusion test. Extracts produced by autoclaving the organisms for 1 hour at 120 degrees C were used as antigen. Antisera against all known types were produced in rabbits. Extracts produced from the two strains in question (Ba?o 36 and Ba?o 107) did not react with any of the knwon type antisera. Antisera against the two strains did not react with extracts of any of the known type strains, but only with extract of their homologous strains. The two new types were designated Type 21 (Ba?o 36) and Type 22 (Ba?o 107).     

种鸭源猪丹毒丝菌分离及血清学调查

从发生生产性能异常的2个种鸭群中分离到2株革兰阳性丝状菌,经16S rRNA基因序列分析鉴定为猪丹毒丝菌。采用多重PCR对分离株编码表面保护性抗原(spa)基因进行扩增,分别获得大小约1 000 bp和900 bp的片段,判定为spaC型和spaB型。毒力检测结果表明,2个分离株对小鼠的半数致死量(LD50)分别为103CFU/0.2 mL和≤102CFU/0.2 mL。药敏试验结果表明,分离株对青霉素类和大部分头孢菌素类抗生素敏感,对氨基糖苷类等药物具有明显的抗性。为进一步了解猪丹毒丝菌对鸭群的感染情况,本研究采用生长凝集试验对来源于3个不同鸭场的种鸭群进行血清学调查,结果,抗丹毒丝菌抗体阳性率(抗体效价≥16)分别为82%、35%和20%,表明鸭群中广泛存在猪丹毒丝菌感染。     

Computerized comparison of the protein compositions of Erysipelothrix rhusiopathiae and Erysipelothrix tonsillarum strains

Protein profiles of six Erysipelothrix rhusiopathiae strains, five Erysipelothrix tonsillarum strains and three Erysipelothrix strains of uncertain taxonomic position were studied by sodium dodecyl sulphate-polyactylamide gel electrophoresis (SDS-PAGE). In a computerized comparison of the protein patterns of the strains, the level of similarity between the strains was determined. The SDS-PAGE protein bands were divided into 14 groups based on molecular weight. The relative distribution of proteins within these groups was used to characterize the strains. These distribution patterns were analysed by computing Pearson's correlation coefficient between strains, and by cluster analysis based on Euclidean distances and the unweighted pair-group method of arithmetic averages (UPGMA). The geometric mean of the similarities calculated by Pearson's correlation coefficient was 0.980 +/- 0.018 between the E. rhusiopathiae strains and 0.979 +/- 0.013 for E. tonsillarum strains. The value was 0.932 +/- 0.036 between the strains belonging to different species. However, a threshold value applicable for identification of a given strain to a species could not be established. Of the three strains of uncertain taxonomic position, the strains designated Rotzunge and Iszap 4 had a protein composition more similar to that of E. tonsillarum than to that of the E. rhusiopathiae type strain. The strain designated Pécs 56, which may be a member of a new species according to literature data, gave inconsistent results by the two methods used. The computerized evaluation method developed here is suitable for the comparison of the protein composition of the strains and for the construction of the protein similarity tree by cluster analysis.