Streptococcus suis infections in pigs in the Netherlands (Part I)

Summary

Data are presented on the incidence of various streptococcal infections in pigs in the Netherlands. 314 Strains isolated in the course of routine post‐mortem diagnosis were examined. The most frequently occurring streptococcus was S. subacidus (bio) type II which was isolated in 31.2% of the cases.

S. suis type 2 (Serogroup R) and S. equisimilis (Serogroup C) constituted 16.2% and 13.7% of the isolates respectively. Besides meningitis, endocarditis and polyserositis S. suis type 2 infections may frequently be associated with pneumonia (42%).

The biochemical profiles of the various S. suis and S. subacidus (bio) types are presented. The profile of both species is almost identical. It seems justified to use the name S. suis for strains with this characteristic profile and to abandon the name S. subacidus. Haemolysis does not appear to be a suitable characteristic to screen for S. subacidus/S.suis types. In comparing three serological methods for typing S. suis type 2, gel precipitation using Fuller's extract and slide agglutination give an almost 100% correlation. These two methods are recommended for serotyping.     

Streptococcus suis infections in pigs in the Netherlands (Part I)

Data are presented on the incidence of various streptococcal infections in pigs in the Netherlands. 314 Strains isolated in the course of routine post-mortem diagnosis were examined. The most frequently occurring streptococcus was S. subacidus (bio) type II which was isolated in 31.2% of the cases. S. suis type 2 (Serogroup R) and S. equisimilis (Serogroup C) constituted 16.2% and 13.7% of the isolates respectively. Besides meningitis, endocarditis and polyserositis S. suis type 2 infections may frequently be associated with pneumonia (42%). The biochemical profiles of the various S. suis and S. subacidus (bio) types are presented. The profile of both species is almost identical. It seems justified to use the name S. suis for strains with this characteristic profile and to abandon the name S. subacidus. Haemolysis does not appear to be a suitable characteristic to screen for S. subacidus/S. suis types. In comparing three serological methods for typing S. suis type 2, gel precipitation using Fuller's extract and slide agglutination give an almost 100% correlation. These two methods are recommended for serotyping.     

猪链球菌病研究进展

猪链球菌(Streptococcus suis)是一种重要的人兽共患病病原体,能够引起猪的疫病,人类感染该菌可导致脑膜炎、败血症,甚至死亡.该菌对养猪业造成严重经济影响,对公共卫生事业构成巨大威胁.由于猪链球菌血清型较多,抗原结构复杂,在临床上又可呈现不同的症状,如败血症、脑膜脑炎、心内膜炎、肺炎、化脓性淋巴结炎、关节炎等,还常常与其他疾病发生合并感染.近几年来,该病的发病率和死亡率有逐年上升趋势.链球菌的致病性已引起临床工作者和科研人员的广泛关注和重视,国内外许多学者对猪链球菌做了大量的研究工作,已发现的猪链球菌2型的致病因子包括荚膜多糖、溶菌酶释放蛋白、细胞外因子、蛋白质片段和IgG结合蛋白、溶血素等.     

Streptococcus suis type 2 infections in pigs in the Netherlands (Part two)

Since 1983 some pig breeding and fattening farms in the Netherlands have been faced with a considerable mortality in pigs due to Streptococcus suis type 2 infections. The most predominant clinical feature of S. suis type 2 infection is meningitis, although sudden deaths often occur. It was noted that some affected farms had imported breeding stock from the United Kingdom. Tonsils of slaughter pigs were collected from herds with and without a history of S. suis type 2 infections. Bacteriological examination was done by using an elective-selective medium. No significant difference was found in carrier rates of S. suis type 2 between clinically healthy and affected herds (38% vs. 45%). A cohort study was carried out by regular bacteriological examination of tonsil biopsies on a farm with a high incidence of streptococcal meningitis. Twenty-seven percent of the pigs were carriers of S. suis type 2 at nine weeks of age. Possible methods for disease control are discussed.     

Streptococcus suis type 2 infections in pigs in the Netherlands (part two)

Summary

Since 1983 some pig breeding and fattening farms in the Netherlands have been faced with a considerable mortality in pigs due to Streptococcus suis type 2 infections. The most predominant clinical feature of S. suis type 2 infection is meningitis, although sudden deaths often occur. It was noted that some affected farms had imported breeding stock from the United Kingdom.

Tonsils of slaughter pigs were collected from herds with and without a history of S. suis type 2 infections. Bacteriological examination was done by using an elective‐selective medium. No significant difference was found in carrier rates of S. suis type 2 between clinically healthy and affected herds (38% vs. 45%).

A cohort study was carried out by regular bacteriological examination of tonsil biopsies on a farm with a high incidence of streptococcal meningitis. Twenty‐seven percent of the pigs were carriers of S. suis type 2 at nine weeks of age. Possible methods for disease control are discussed.     

Experimental infections of mice and pigs with Streptococcus suis type 2.

Five inbred strains of mice were tested for their susceptibility to Streptococcus suis type 2 including the type strain, two isolates from meningitis in pigs and two isolates from tonsils of clinically healthy pigs. C57BL/6, ICR and ddY strain mice showed lower susceptibility to all strains of S. suis type 2 than BALB/c and SS strain mice. The type strain and the isolates from diseased pigs produced septicaemia and meningitis in BALB/c and SS mice inoculated with 10(8) colony forming unit of the bacteria and 60 to 100% of these infected mice died. On the other hand, mice inoculated with the isolates from healthy pigs showed mild clinical signs but none of them died. In BALB/c mice which died or developed nervous signs, the purulent meningo-encephalitis, myocarditis, ophthalmitis, labyrinthitis and otitis media were observed. S. suis type 2 antigen was demonstrated in these lesions by immunoperoxidase staining using rabbit S. suis type 2 antiserum. These results were similar to those in the experimentally infected pigs with these virulent and avirulent strains against mice. These results indicate that BALB/c and SS strains of mice are useful as an experimental model of S. suis type 2 infections in pigs, and that there are virulent and avirulent strains against mice and pigs among the strains of S. suis type 2.     

中药水提物对体外猪链球菌生物被膜作用的试验

猪链球菌耐药性与生物被膜的形成有关,本试验选取常用的20味清热解毒的中药,采用微量稀释法测定20味中药水提物的最小抑菌浓度(MIC)和最小杀菌浓度(MBC),采用卡尔加里生物被膜装置和平板稀释法测定20味中药在亚MIC(1/2 MIC)药物浓度下对生物被膜的干预作用,结果表明:丁香叶、金银花、黄芩、穿心莲、黄柏和鱼腥草等中药水提物干预生物被膜效果显著(P0.05)大黄、黄连水提物干预生物被膜效果极显著(P0.01),通过细菌计数发现,0~72h,1/2MIC中药提取物对猪链球菌数量影,响不显著(P0.05)。丁香叶、大黄和黄连水提物对生物被膜中的猪链球菌具有很好的杀灭作用(P0.05)。     

Identification and characterization of Streptococcus suis

A total of 188 Streptococcus suis strains isolated from pigs with various lesions, mainly bronchopneumonia, were identified using classical biochemical methods and using the API 20 STREP system. The serological classification was performed by precipitation reactions after Lancefield extraction, slide-coagglutinations and capsular reaction tests. Fifty-nine strains belonged to Types 1, 1/2 or 2, 78 strains to Types 3-8 and 51 strains were non-typable. The results of the different tests and the biochemical differences between the different serotypes are discussed.     

猪链球菌对红霉素耐药性的研究

从发病猪体内分离、鉴定猪链球菌，采用肉汤稀释法和纸片琼脂扩散法筛选对红霉素耐药的猪链球菌，用双纸片法确定耐药株的耐药表型，通过聚合酶链反应检测对红霉素耐药的基因ermb/mefA。猪链球菌对红霉素的耐药表型为cMLS表型，即同时对克林霉素耐药。在3株红霉素耐药株中扩增到ermb基因，其余未能检测到ermb或mefA基因。     

猪链球菌检测及猪链球菌病防治的研究进展

猪链球菌（Streptococcus suis）能引起猪的脑膜炎、心内膜炎、关节炎、肺炎和败血症，并能感染人，是一种重要的人畜共患病病原。国内外许多学者致力于该菌的致病性、快速准确诊断技术以及综合防治研究。本文对猪链球菌的毒力因子、检测方法和疾病防治等方面的研究进展进行了综述。     

猪致病性链球菌的分离鉴定

采集33例临床症状疑似猪链球菌感染猪的全血及内脏器官进行涂(触)片染色镜检,取有球菌感染的样品16份进行血琼脂平板分离纯化试验;根据血琼脂平板上菌落形态、溶血情况及对单个菌落涂片染色镜检结果,共筛选出12份可疑样品,进一步采用液体培养基对12份样品进行增菌及纯化培养;选取纯化培养菌进行链球菌生化试验,结果共鉴定出11株纯化的猪链球菌;11株猪链球菌均对小鼠表现出高致病力.     

Streptococcus suis isolated from pigs in Finland

A total of 58 Streptococcus suis strains were isolated from deceased pigs submitted to the National Veterinary Institute, Regional Laboratory in Kuopio, Finland, over a 3 1/2 year period, most frequently from cases of pneumonia. The bacteria were isolated from cases of meningitis, sepsis, rhinitis, endocarditis and abortion. S. suis was also isolated from nasal cavity, lung and brain of some sick piglets without signs of inflammation. Further S. suis was detected in 12 out of 107 tonsils of healthy fatteners tested. S. suis strains were identified by biochemical methods followed by typing. The most common capsular types were 7, 3 and 2, respectively. Only one type 1 strain and no types 6 and 9 strains were found. All S. suis strains tested were sensitive to penicillin and ampicillin.S. suis is not uncommon in Finnish pig herds. S. suis may be regarded as a potentially pathogenic organism which under certain predisposing conditions may cause serious disease.     

Presence of the Streptococcus suis suilysin gene and expression of MRP and EF correlates with high virulence in Streptococcus suis type 2 isolates

Nineteen Streptococcus suis type 2 isolates that had been analyzed previously for hemolysin production, ribotype, and virulence in pigs were examined for presence of the gene coding for suilysin by PCR amplification, and southern blot and hybridization techniques. Based on southern blot and hybridization analysis, all isolates tested contained at least a portion of the suilysin gene. PCR amplification of the entire gene resulted in gene fragments from five of the seven highly virulent isolates and none of the moderately virulent or avirulent isolates. Additional PCR analysis showed that mutation or deletions at the 5′ end of the suilysin gene in the less virulent isolates prevented amplification of the sly gene fragment from those isolates. The MRP+ (muramidase-released protein) EF+ (extracellular protein) phenotype was also expressed by the same five highly virulent/sly+ isolates.     

Mutagenesis of Streptococcus equi and Streptococcus suis by transposon Tn917

Genetic tools for studying streptococci are much less sophisticated than those that are available for many other bacterial genera. In this paper, we describe the development of a transposon mutagenesis system that we have used to mutate two important veterinary streptococci, Streptococcus equi and Streptococcus suis. The system uses a temperature-sensitive suicide vector to deliver Tn917 via electroporation, transposing Tn917 into the chromosomal DNA of the two streptococci. The transposon insertions can be rescued from the streptococcal chromosomes by plasmid rescue and selection in E. coli, with subsequent insertion site analysis by DNA sequencing. Transposition appeared to have occurred in an essentially random fashion when chromosomal DNA of S. suis and S. equi mutants was analysed by Southern blotting. However, when analysis of 60 S. equi mutants was carried out using the S. equi genome sequence database, 60% of transposon insertions had occurred within a 15 kb region of the genome whereas the other insertions appeared to have occurred essentially randomly. This finding suggests that Southern blot analysis for assessing the randomness of transposon libraries may need to be interpreted with caution. However, this observation notwithstanding, the Tn917 based system described in this paper will facilitate the study of S. suis and S. equi.     

Immunization of mice against Streptococcus suis serotype 2 infections using a live avirulent strain.

In this study, the IgG response of mice injected with two virulent strains and one avirulent Streptococcus suis capsular type 2 strain was compared by Western blotting. The serum from mice immunized against the avirulent strain could recognize most proteins of the various strains tested and similar results were obtained with serum from mice injected with virulent strains. The live avirulent strain was injected twice (days 0 and 10) to groups of five mice, and four virulent strains from different geographical origins were used to challenge the animals. All mice, except one in one group, survived the challenge. These results suggest that a live avirulent strain could be used for immunization of swine, the natural host.     

抗生素与中草药联用对猪链球菌体外抑菌活性分析

为观察中草药与抗菌药物联用对猪链球菌的体外抑菌效果,用试管二倍稀释法,分别测定4种中草药水提取物、4种抗菌药物及中草药和抗菌药物的多个配伍对猪链球菌的最小抑菌浓度（MIC）。结果显示,所选中草药抗菌药物及其联合用药对猪链球菌均有较好的抑制作用,且联合用药的抗菌作用表现为部分增强,其中对猪链球菌作用最明显的配伍是黄柏＋氨苄西林、石榴皮＋氨苄西林,野菊花＋氨苄西林、中药复方＋氨苄西林、石榴皮＋青霉素G和黄柏＋壮观霉素,其最小抑菌浓度为0.977 mg/mL。     

猪链球菌病的流行病学

猪链球菌（Streptococcus suis）可感染人和动物,引起脑膜炎、败血症、关节炎等,甚至死亡。随着分子生物学、微生物学和流行病学的发展,对猪链球菌（病）的流行病学有了一些新的认识。本文围绕猪链球菌的特性、流行特点以及我国和其他国家的猪链球菌病流行情况等4方面,系统介绍了该病当前的流行范围、程度、趋势和规律等,为本病的防控提供可参考的流行病学依据。     

湖南省猪链球菌的分离与鉴定

从病猪脏器病料中通过细菌培养、生化试验分离鉴定出了121株猪链球菌.经PCR技术鉴定马链球菌兽疫亚种28株,占23.1%,猪链球菌24株,占19.8% ,其中猪链球菌2型4株,占3.3%,猪链球菌9型2株,占1.7%,猪链球菌1型和7型都没检测到,证实省内除了猪链球菌2型外,也存在其他血清型的猪链球菌.     

猪链球菌病的诊断和防治

1　临床症状及剖检变化某猪场存栏猪 5 0 0 0余头 ,于 1 999年 1 0月发生该病 ,从保育猪舍开始 ,2～ 3天发病蔓延到整个猪场 ,先后发病 82 0头 ,经紧急治疗仍死亡 3 2 5头 ,病死率为 3 9.6 %。表现突然发病不食 ,体温 41～43℃ ,结膜潮红、流泪。有浆液性鼻液 ,呼吸困难 ,腹下、四肢、耳尖等处皮肤呈出血性紫斑 ,少部分育成病猪表现明显的神经症状 ,共济失调 ,倒地四肢做游泳状 ,磨牙或口吐白沫 ,大多于 1～ 3天内死亡 ,症状较轻及治愈者 ,偶留有跛行或生长不良。剖检变化差异较大 ,主要为全身淋巴结充血肿胀 ,脾脏肿大 1～ 3倍 ,边缘发生出…