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1.
Three swine commercial farms with high mortality rates in nursery pigs due to Streptococcus suis serotype 2 were studied. Brain samples from diseased animals were collected for a period of 6 to 10 mo and used to isolate the strain that was responsible for the mortality (virulent strain) in each farm. Tonsil swabs from piglets at 5, 10 and 15 d were taken to assess both total colonization and colonization by the virulent strain. The effect of sow vaccination against S. suis on colonization was evaluated in 1 of the farms. All suspect tonsil isolates were identified biochemically and then tested against serotype 2. The genomic patterns of serotype 2 isolates were compared to that of the virulent strain using Rep-PCR. Results showed that total colonization by S. suis occurred very early in the pigs' life, with most animals being colonized by weaning age. Prevalence of colonization by serotype 2 strains was much lower than total colonization. After comparing serotype 2 isolates with the virulent strains, only 1 tonsillar isolate had the same genomic pattern as the virulent strain and it belonged to a 4-week-old weaned pig. The genomic pattern of the virulent strain was not found in any tonsillar isolate from 15-day-old or younger pigs. Although limited by sample size, sow vaccination against S. suis increased total colonization at the same time significantly decreasing colonization by serotype 2 strains. Even though most pigs are colonized early in age by S. suis, colonization by the virulent strain is of low prevalence and delayed in time. This could constitute a risk factor for developing the disease later in time, because animals would be colonized when maternal immunity is no longer present, allowing the organism to become systemic.  相似文献   

2.
2015年3月,江苏省泰兴市某猪场仔猪发生疑似副猪嗜血杆菌病。经过一系列综合诊断,初步诊断为副猪嗜血杆菌病。经药敏试验选择高敏药物进行治疗,最终控制和扑灭该病。主要介绍了该起病例的诊治经过,并与猪链球菌病的病理变化进行了鉴别,以期为兽医同仁提供参考。  相似文献   

3.
A standardized model of Streptococcus suis type 2 infection in specific-pathogen-free piglets, housed in high-security barns, was used to compare the virulence of 3 French field strains of S. suis serotype 2 isolated from tonsils of a healthy pig (strain 65) or from diseased pigs (meningitis, strain 166', or septicemia, strain 24). In one of the 2 trials, 7-week-old pigs, in 3 groups of 8, were inoculated intravenously with 2 x 10(8) colony-forming units of S. suis type 2. In each group, 1 uninfected animal was a sentinel. Eight animals were also used as negative control group. The experiment was repeated under similar conditions with strains 65 and 166'. Virulence differed markedly among these S. suis strains when clinical signs, zootechnical performances, lesions, and bacteriological data were analyzed. Strain 65 did not induce clinical signs in inoculated pigs. In contrast, pigs infected with the other 2 strains exhibited clinical signs and typical lesions of S. suis type 2 infections. Differences in virulence were also observed between the 2 virulent strains. Sentinel animals exhibited the same manifestations as those recorded in inoculated piglets. Results were similar in the second trial, indicating that under the present experimental conditions, results were reproducible. The standardized conditions described in this study could be a useful tool to further study about the S. suis infection.  相似文献   

4.
副猪嗜血杆菌人工感染猪的病理学观察   总被引：7，自引：0，他引：7  
用副猪嗜血杆菌分离株感染断奶仔猪,发病仔猪临床表现为体温中度升高、精神不振、被毛粗乱、站立不稳、厌食、呼吸困难。尸体剖检,可见胸腹腔纤维素渗出严重,有大量的渗出液、肺出血及脑充血等;病理组织学表现为,肺脏、心脏、脾脏等脏器含有大量的中性粒细胞的纤维蛋白性多发性浆膜炎、脑膜炎及支气管肺炎。结果表明,此分离株为一高致病潜力的菌株。  相似文献   

5.
为了解山东地区副猪嗜血杆菌病的流行情况和流行菌株的生物学特性及致病性,将2016-2018年山东省12个地区送检的103个发病猪的病料进行细菌分离,并对疑似菌株进行形态学观察、PCR鉴定及血清型鉴定,对两株流行菌株进行了培养特性观察、生化特性鉴定、药敏试验及致病性研究。最终分离获得29株副猪嗜血杆菌,分离率为28.16%,其中血清型4型和5型最为流行,其次是1型和12型。该病多发于春秋两季,31~50日龄的仔猪感染率最高。两株流行菌株LZ株和LC株均对青霉素类、头孢类等药物高度敏感,LZ株对庆大霉素、卡那霉素等中度敏感,对林可霉素、链霉素不敏感,LC株对庆大霉素、林可霉素等中度敏感,对卡那霉素、链霉素不敏感;生化特性试验结果显示,LC株和LZ株的硝酸盐还原试验、接触酶试验、葡萄糖发酵试验以及果糖发酵试验的结果均为阳性,吲哚试验、氧化酶试验、甘露醇发酵试验的结果均为阴性;动物致病性试验表明LZ株和LC株均具有较强的毒力,最小发病剂量分别为4.5×10^9 CFU和6.0×10^9 CFU。该研究为副猪嗜血杆菌病的防治提供了重要的参考依据。  相似文献   

6.
The effect of vaccination with a killed whole-cell vaccine of extracellular factor-positive Streptococcus suis serotype 2 (S suis 2 EF(+)) combined with medication with amoxicillin on the presence of virulent S suis 2 EF(+) strains on the tonsils of sows and their offspring was evaluated. In two herds, 14 pregnant sows that carried these virulent strains, as detected by PCR in three consecutive tonsillar brush samples, were selected and randomly assigned to be treated or left untreated as controls. The treated sows were vaccinated at six and three weeks before the expected farrowing date and medicated from one week before expected farrowing until the end of the experiment. Two weeks before parturition, the sows were housed in individual isolation farrowing rooms, and the sow and its litter were sampled by using tonsil brushes and tonsil swabs, respectively. Approximately 27 days postpartum, the sows and their piglets were euthanased and their tonsils were collected and analysed by pcr. No S suis 2 EF(+) could be detected in the tonsils of the seven treated sows, but the tonsils of the seven untreated sows remained positive. Only one of the litters of the untreated sows became infected, five days after birth, and none of the litters of the treated sows became infected.  相似文献   

7.
Studies were conducted at swine facilities in Illinois and North Carolina to evaluate the effect of treatment with doramectin injectable solution on transmission prevention of Sarcoptes scabiei var. suis from sows to nursing piglets. Approximately 42 days prefarrowing, 58 mange-free sows were experimentally infested with 200 S. scabiei in each ear. Seven to fourteen days prior to farrowing, 22 sows were given doramectin injectable intramuscularly at a dose of 300 microg/kg of body weight. A total of 21 sows served as untreated controls. Skin scrapings for mite counts and lesion scoring were performed on sows before treatment on day 21, and on either day 35 or 42. Each sow was observed on days 0, 7, 14, 21, 28, and 35 or 42 for the incidence of scratching/rubbing. Skin scrapings, lesion scoring, and observation of scratching/rubbing were performed on the piglets after weaning and at the end of the nursery stage. Geometric mean mite counts of the untreated sows were 0.70 and 0.26 on days 21 and 35 or 42, respectively, and 0.00 for doramectin-treated sows over the same time periods (P<0.05). Lesions scores and the incidence of scratching/rubbing were both higher in the untreated sows as compared to the doramectin-treated sows during the same time periods (P<0.05). Geometric mean mite counts of piglets farrowed by untreated sows were 0.50 and 0.60 after weaning and at the end of the nursery stage, respectively, and 0.00 for piglets from doramectin-treated sows over the same time periods (P>0.05). Lesion scores and the incidence of scratching/rubbing were both higher in piglets from untreated sows as compared to those piglets from doramectin-treated sows (P<0.05). Treating S. scabiei-infested sows with doramectin injectable solution before farrowing eliminated mite infestation and prevented the transmission of S. scabiei to piglets.  相似文献   

8.
Virulence of Streptococccus suis capsular type 2 strain 89-1591 has been controversial in literature. A standardized experimental model with specific-pathogen free piglets was used for a new evaluation of this strain. Twenty-nine piglets were allotted in 4 separated groups. Group 1 consisted of negative control animals which received broth medium. Groups 2, 3, and 4 were intravenously challenged with 2 mL of S. suis, strains 1330, 89-1591, and 166', respectively. The strain 1330 is a recognized avirulent Canadian strain. The strain 166' is a reference French virulent isolate. Pigs inoculated with strain 1330 did not present clinical signs of a S. suis infection. Contamination in organs and bacterial blood circulation were rare and lesions were almost non-existent. Infection of pigs with S. suis strain 89-1591 (group 3) and 166' (group 4) caused severe clinical problems, animals infected with S. suis 166' were the most affected. Pigs presented with clinical signs such as high body temperature, lameness, nervous symptoms, and even mortality. Lesions associated with S. suis were numerous for both strains, but more evident in animals of group 4. It can be concluded that S. suis strain 89-1591 is virulent, although its virulence seems to be lower than that of the French strain. Results of an experimental infection with strain 89-1591 may depend on different factors such as the route of inoculation and the immunological status of the animals used. Using conventional animals, with an unknown status regarding previous S. suis infections, equivocal results may be obtained, and this may explain differences reported by some authors with the same strain.  相似文献   

9.
Haemophilus parasuis can cause pneumonia and systemic disease in swine but it is also a coloniser of the upper respiratory tract of healthy pigs. These differences in pathogenicity are probably the result of diverse mechanisms of virulence in different strains. Since serum-resistance is a feature frequently found in systemic pathogens, 31 H. parasuis strains of different clinical origin were tested and a variety of serum susceptibility levels detected. Nasal strains from healthy piglets were sensitive to the bactericidal effect of the serum, while systemic strains were mainly resistant. The pulmonary strains included both serum-sensitive and serum-resistant strains. Interestingly, the serum-resistant pulmonary strains were isolated from animals with systemic lesions. Heat-treatment of the sera abolished the bactericidal activity, indicating that complement is a key factor in this effect. Equivalent susceptibility was observed with rabbit and porcine sera, and the presence of H. parasuis specific antibodies did not increase the killing of the strains by serum. In an attempt to associate serum-resistance to a surface determinant of the bacteria, agglutination in acriflavine was tested but no direct link with serum susceptibility was found. The results indicate that serum-resistance is a virulence mechanism in H. parasuis.  相似文献   

10.
副猪嗜血杆菌的分离鉴定及16S rRNA序列分析   总被引：1，自引：1，他引：0  
从云南某规模化养猪场病猪肺脏分离到1株革兰氏阴性小杆菌,经细菌生化鉴定、PCR鉴定和16S rRNA序列比对鉴定为副猪嗜血杆菌。抗生素药物敏感试验结果表明,分离菌株对四环素、红霉素、氯霉素、头孢噻吩高敏;对庆大霉素、氧氟沙星、诺氟沙星中敏;对磺胺甲唑耐药。16S rRNA分析结果表明,该分离株与GenBank中的Hps参考株AB078973(基因登录号)同源性为100%,将分离菌株鉴定为副猪嗜血杆菌。16S rRNA遗传进化关系表明,分离株与副猪嗜血杆菌3株血清5型参考株AB078972、AB078973、AB078974的16S rRNA序列位于一个分支上,遗传进化关系最近,它们之间的核苷酸同源性在99.0%~99.4%之间,初步鉴定为血清5型副猪嗜血杆菌,致病性试验结果表明,分离菌株对小白鼠有强致病性,命名为YN-1株。  相似文献   

11.
副猪嗜血杆菌分离鉴定及药敏试验   总被引：1，自引：0，他引：1  
副猪嗜血杆菌能够引起猪的多发性浆膜炎、关节炎和脑膜炎等,是影响猪的最重要细菌之一,目前在所有的主要养猪国家均有存在。为了弄清河南省副猪嗜血杆菌病流行情况,2012年-2015年,从河南不同地区猪场送检的疑似病料,进行副猪嗜血杆菌分离和鉴定,共分离到5株细菌,通过细菌形态观察、培养特征鉴定、生化试验、PCR检测,鉴定为副猪嗜血杆菌,分别命名为A6-fei、C3-xin、C12-xin、D2-fei和E1-fei。采用纸片扩散法,对分离5株副猪嗜血杆菌进行药敏试验,其结果表明所分离的5株副猪嗜血杆菌的药物敏感性不尽相同,各分离菌株对头孢噻肟、氟苯尼考星最敏感,对复方新诺明敏感性最差,其中菌株C3-xin对复方新诺明、庆大霉素、卡那霉素、青霉素完全耐药。表明副猪嗜血杆菌病在河南省依然存在,并且不同地区菌株对常用药物的敏感性各不相同,应当引起养猪场重视。  相似文献   

12.
Streptococcus (S.) suis is an invasive porcine pathogen causing meningitis, septicemia, arthritis and other diseases. Studies on pathogenesis as well as vaccine trials have focused on serotype 2 strains, which are worldwide the most prevalent among invasive isolates. However, in Europe serotype 9 strains also contribute substantially to S. suis-associated invasive diseases of piglets. The objective of this study was to determine the virulence of an MRP* SLY+ serotype 9 S. suis strain in comparison to an MRP+ EF+ SLY+ serotype 2 strain. Experimental intranasal and intravenous infections of 7-8 weeks old SPF piglets were investigated with regard to clinic and pathology. In contrast to the virulent serotype 2 strain, the serotype 9 strain did not cause disease with clinical manifestations after intranasal administration. However, histological screenings of these animals revealed pathological lesions, such as mild focal suppurative meningitis. Clinical manifestations related to meningitis, arthritis and serositis could be induced by intravenous application of this serotype 9 strain. Bacteriological culture and immunohistochemistry of the brain confirmed association with the S. suis challenge strains in all cases with clinical manifestations. Interestingly, expression of MRP within meningitis lesions was demonstrated for both pathotypes via immunohistochemistry. In conclusion, this study demonstrates that MRP* SLY+ serotype 9 strains are less virulent for growers than MRP+ EF+ SLY+ serotype 2 strains. Thus, intravenous application of this serotype 9 strain is required to evaluate heterologous protection in the course of vaccine development based on serotype 2 strains in the future.  相似文献   

13.
A total of 28 Haemophilus parasuisc （H.parasuis） isolates were isolated from 48 farms in Longyan. Strains were confirmed by biochemical tests and PCR. Serovar 5 was the most prevalent, followed by serovar 4. 14 days old piglets were immunized with inactivated bacterin using seorvar 4 isolate LY04 and seorvar 5 isolate LY052, respectively, which were representative strains, and the results of efficacy test showed that the protection rates were both 66.7%.  相似文献   

14.
OBJECTIVE: To characterize the genetic diversity of Haemophilus parasuis field isolates with regard to serovar, herd of origin, and site of isolation. SAMPLE POPULATION: Isolates of H parasuis obtained from pigs in 15 North American herds and multi-farm systems. PROCEDURE: 98 H parasuis isolates were genotyped with the enterobacterial repetitive intergeneic consensus based-polymerase chain reaction (ERIC-PCR) technique and serotyped via agar gel precipitation test. Genomic fingerprints were analyzed and dendrograms were constructed to identify strains from the same serovar group, herd of origin, or isolation site and to evaluate the genetic variability within these categories. RESULTS: Serovar 4 (39%) and nontypeable (NT) isolates (27%) were most prevalent. Thirty-four distinct strains were identified among the 98 isolates, using a 90% similarity cutoff. Strains from serovar 4 and NT isolates had high genetic diversity (12 and 18 strains, respectively). One to 3 major clusters of prevalent strains could be identified in most of the evaluated herds. Haemophilus parasuis strains isolated from the upper respiratory tract were either serovar 3 or NT isolates. Potentially virulent strains (isolated from systemic sites) were either serovars 1, 2, 4, 5, 12, 13, or 14, or NT isolates. CONCLUSIONS AND CLINICAL RELEVANCE: Although H parasuis had high genetic diversity overall, only a few strains caused disease in these herds. The ERIC-PCR technique was more discriminative than serotyping, and a broad genetic variety was observed within particular serovar groups.  相似文献   

15.
Using an indirect fluorescent antibody test, 54 per cent of 734 palatine tonsils of conventional pigs slaughtered in Australia and New Zealand were found to be infected with Streptococcus suis type 1 and 73 per cent of 959 were infected with S suis type 2. Variations in the prevalence of infection in pigs from different herds were thought to be due to differences in the sample sizes rather than to real differences in the prevalence between herds. The prevalence of infection with S suis was similar in pigs of either sex and in different age groups. Streptococcus suis type 2 was detected in the blood of 3 per cent of apparently normal pigs slaughtered at a meat processing plant. The presence of this organism in edible tissue may pose a health risk to consumers and meat-workers. Both S suis types 1 and 2 were detected in the vaginas and uteri of slaughtered pigs and the female reproductive tract could be another site for the carriage of infection. Piglets from sows with vaginas infected with S suis type 2 became infected earlier than piglets from sows with uninfected vaginas. No infected male reproductive tracts were detected and venereal transmission of S suis therefore appears unlikely. Three specific pathogen free herds were found to be free from infection with both S suis types 1 and 2. It is concluded that hysterectomy derived piglets are delivered free from infection, whereas some piglets born to sows with uterine and vaginal infections are either born infected or become infected at, or soon after, birth.  相似文献   

16.
Haemophilus parasuis: new trends on diagnosis, epidemiology and control   总被引：35，自引：0，他引：35  
Haemophilus parasuis is a commensal organism of the upper respiratory tract of conventional pigs, but under appropriate conditions can invade and cause severe systemic disease, characterized by fibrinous polyserositis, arthritis and meningitis. Factors involved in systemic invasion by H. parasuis remain largely unknown. However, major advances in our knowledge of H. parasuis include (1) development of a species-specific PCR test to detect H. parasuis in clinical samples, (2) study of molecular epidemiology within and between herds, by use of a repetitive element-based PCR, (3) the proposal of an alternative serotyping technique, (4) development and testing of a new in vivo model for pathogenesis and virulence studies, and (5) use of controlled exposure of young pigs to low doses of live, virulent H. parasuis strains to reduce nursery mortality in affected swine herds.  相似文献   

17.
Experimental airborne transmission of Streptococcus suis type 2 was studied in specific pathogen free piglets. Forty piglets were allotted to five groups of eight 7-week-old animals and housed in three separated units. Negative control pigs (group 1) were housed in unit A and infected batches were housed in units B (group 2) and C (groups 4). In units B and C, non-inoculated groups (groups 3 and 5, respectively), 40 cm distant from the respective inoculated group and without any physical contact between them, also took place. Six animals of groups 2 and 4 were inoculated intravenously with 2 x 10(8) colony forming units (cfu) of a mild and a high virulent S. suis strains, respectively. The remaining animals in these groups and pigs from groups 1, 3, 5 received broth medium in the same way. Differences among virulence of S. suis capsular type 2 were observed in inoculated pigs of groups 2 and 4. Pigs from group 2 became carriers, showing only mild symptoms. By contrast, animals from group 4 presented an acute form of the disease. All the indirect contact pigs in groups 3 and 5 had S. suis in palatine tonsils from day 6 after the infection and they presented clinical manifestations similar to those observed in experimentally infected pigs. Two direct contact animals were also contaminated in the upper respiratory tract but surprisingly they did not show any symptoms. Airborne transmission of S. suis in experimentally pigs was demonstrated in the present study. Indirect infections, as described in this study, are a more realistic way to infect pigs than other experimental procedures and may be used to further study the pathogenesis of the infection caused by this important pathogen.  相似文献   

18.
To study the occurrence and distribution of various strains of Haemophilus parasuis in southern Ontario swine, organisms isolated from healthy swine, from specific pathogen-free and conventional herds, and from disease cases were examined using restriction endonuclease fingerprinting analysis. In most herds, several strains of H. parasuis could be detected although one or two strains usually predominated. Individual animals were colonized by a single or limited number of strains. In several cases, the same strains were isolated from more than one specific pathogen-free herd. Conventional herds carried a more heterogeneous population of H. parasuis. Only one strain was isolated which was common to more than one conventional herd. No strains were isolated which were common to both specific pathogen-free and conventional herds. None of the strains isolated from disease cases were found in healthy conventional or specific pathogen-free swine examined in this study.  相似文献   

19.
Haemophilus parasuis causes Gl?sser's disease as well as a number of other diseases in pigs. The diagnosis of H. parasuis-associated disease is usually established by clinical signs, pathological findings and bacterial isolation but diagnosis is complicated by the existence of non-virulent strains and the early colonisation of the upper respiratory tract of healthy piglets. Moreover, several strains can be found on a farm and even within a single animal so it is important to determine the specific strain that is causing the clinical outbreak. Recently, genotyping methods have been developed with the goal of correlating genotype with the degree of virulence of H. parasuis strains. The association between genotype and virulence in H. parasuis is challenging due to the lack of knowledge of the complete genomic sequence and virulence factors of this bacterium.  相似文献   

20.
The objective of this study was to determine whether Bordetella bronchiseptica would predispose to colonization or disease with Haemophilus parasuis. Three experiments were completed. In the first experiment, three groups of pigs (10 pigs/group) were inoculated intranasally with either B. bronchiseptica, H. parasuis, or with B. bronchiseptica followed by H. parasuis 1 week later. A fourth group of 10 pigs served as a non-infected control group. The second experiment was like the first, except that there were only five pigs per experimental group. The third experiment consisted of only two groups (10 pigs/group), one of which was inoculated intranasally with H. parasuis, whereas the other was inoculated with B. bronchiseptica followed by H. parasuis 1 week later. Pigs were necropsied 1-2 weeks after inoculation with H. parasuis. Mean nasal colonization by H. parasuis was significantly higher in the coinfected groups compared to the groups infected with H. parasuis alone. Pneumonia was present in 9/25 pigs coinfected with B. bronchiseptica and H. parasuis, 5/25 pigs infected with H. parasuis alone, 1/15 pigs infected with B. bronchiseptica alone, and in none of the pigs in the non-inoculated groups. Thus, B. bronchiseptica increased colonization of the upper respiratory tract with H. parasuis.  相似文献   

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