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Differences in the Population Structure of Invasive Streptococcus suis Strains Isolated from Pigs and from Humans in the Netherlands  [PDF]
Constance Schultsz, Ewout Jansen, Wendy Keijzers, Anja Rothkamp, Birgitta Duim, Jaap A. Wagenaar, Arie van der Ende
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033854
Abstract: Streptococcus suis serotype 2 is the main cause of zoonotic S. suis infection despite the fact that other serotypes are frequently isolated from diseased pigs. Studies comparing concurrent invasive human and pig isolates from a single geographical location are lacking. We compared the population structures of invasive S. suis strains isolated between 1986 and 2008 from human patients (N = 24) and from pigs with invasive disease (N = 124) in the Netherlands by serotyping and multi locus sequence typing (MLST). Fifty-six percent of pig isolates were of serotype 9 belonging to 15 clonal complexes (CCs) or singleton sequence types (ST). In contrast, all human isolates were of serotype 2 and belonged to two non-overlapping clonal complexes CC1 (58%) and CC20 (42%). The proportion of serotype 2 isolates among S. suis strains isolated from humans was significantly higher than among strains isolated from pigs (24/24 vs. 29/124; P<0.0001). This difference remained significant when only strains within CC1 and CC20 were considered (24/24 vs. 27/37,P = 0.004). The Simpson diversity index of the S. suis population isolated from humans (0.598) was smaller than of the population isolated from pigs (0.765, P = 0.05) indicating that the S. suis population isolated from infected pigs was more diverse than the S. suis population isolated from human patients. S. suis serotype 2 strains of CC20 were all negative in a PCR for detection of genes encoding extracellular protein factor (EF) variants. These data indicate that the polysaccharide capsule is an important correlate of human S. suis infection, irrespective of the ST and EF encoding gene type of S. suis strains.
Development of Multiplex PCR Assays for the Identification of the 33 Serotypes of Streptococcus suis  [PDF]
Zhijie Liu, Han Zheng, Marcelo Gottschalk, Xuemei Bai, Ruiting Lan, Shaobo Ji, Haican Liu, Jianguo Xu
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072070
Abstract: Streptococcus suis is an important zoonotic agent causing severe diseases in pigs and humans. To date, 33 serotypes of S. suis have been identified based on antigenic differences in the capsular polysaccharide. The capsular polysaccharide synthesis (cps) locus encodes proteins/enzymes that are responsible for capsular production and variation in the capsule structures are the basis of S. suis serotyping. Multiplex and/or simplex PCR assays have been developed for 15 serotypes based on serotype-specific genes in the cps gene cluster. In this study, we developed a set of multiplex PCR (mPCR) assays to identify the 33 currently known S. suis serotypes. To identify serotype-specific genes for mPCR, the entire genomes of reference strains for the 33 serotypes were sequenced using whole genome high-throughput sequencing, and the cps gene clusters from these strains were identified and compared. We developed a set of 4 mPCR assays based on the polysaccharide polymerase gene wzy, one of the serotype-specific genes. The assays can identify all serotypes except for two pairs of serotypes: 1 and 14, and 2 and 1/2, which have no serotype-specific genes between them. The first assay identifies 12 serotypes (serotypes 1 to 10, 1/2, and 14) that are the most frequently isolated from diseased pigs and patients; the second identifies 10 serotypes (serotypes 11 to 21 except 14); the third identifies the remaining 11 serotypes (serotypes 22 to 31, and 33); and the fourth identifies a new cps cluster of S. suis discovered in this study in 16 isolates that agglutinated with antisera for serotypes 29 and 21. The multiplex PCR assays developed in this study provide a rapid and specific method for molecular serotyping of S. suis.
Secondary infection with Streptococcus suis serotype 7 increases the virulence of highly pathogenic porcine reproductive and respiratory syndrome virus in pigs
Min Xu, Shujie Wang, Linxi Li, Liancheng Lei, Yonggang Liu, Wenda Shi, Jiabin Wu, Liqin Li, Fulong Rong, Mingming Xu, Guangli Sun, Hua Xiang, Xuehui Cai
Virology Journal , 2010, DOI: 10.1186/1743-422x-7-184
Abstract: Respiratory disease, diarrhea, and anorexia were observed in all infected pigs. Signs of central nervous system (CNS) disease were observed in the highly pathogenic PRRSV (HP-PRRSV)-infected pigs (4/12) and the coinfected pigs (8/10); however, the symptoms of the coinfected pigs were clearly more severe than those of the HP-PRRSV-infected pigs. The mortality rate was significantly higher in the coinfected pigs (8/10) than in the HP-PRRSV- (2/12) and SS7-infected pigs (0/10). The deceased pigs of the coinfected group had symptoms typical of PHFS, such as high fever, anorexia, and red coloration of the ears and the body. The isolation rates of HP-PRRSV and SS7 were higher and the lesion severity was greater in the coinfected pigs than in monoinfected pigs.HP-PRRSV infection increased susceptibility to SS7 infection, and coinfection of HP-PRRSV with SS7 significantly increased the pathogenicity of SS7 to pigs.Porcine reproductive and respiratory syndrome (PRRS) is a threat to the swine industry, and has spread globally to almost every country involved in pig farming, with a few exceptions like Sweden, Switzerland, New Zealand, and Australia [1-4]. PRRS mainly affects pigs and sows; it mainly causes premature delivery, miscarriage, stillbirth, and mummies in sows, and severe pneumonia, edema, and conjunctivitis in pigs. Previous studies have shown that coinfection of PRRSV and bacteria, such as Streptococcus suis, aggravates PRRS [5]. It has been confirmed that PRRSV-infected pigs are more susceptible to S. suis serotype 2 (SS2) infection, and the mortality rate of coinfected pigs is significantly higher than that of PRRSV infected pigs. While the clinical symptoms of both PRRSV infected and coinfected pigs were similar, the incidence of fever in coinfected pigs was higher than that in monoinfected pigs [6].Since 2006, an unprecedented epidemic of porcine high fever syndrome (PHFS) has spread through the Chinese swine industry, resulting in the culling of an estimated 2
Understanding Streptococcus suis serotype 2 infection in pigs through a transcriptional approach
Manli Liu, Liurong Fang, Chen Tan, Tiansi Long, Huanchun Chen, Shaobo Xiao
BMC Genomics , 2011, DOI: 10.1186/1471-2164-12-253
Abstract: A total of 3,002 differentially expressed transcripts were identified in the three tissues, including 417 unique genes in brain, 210 in lung and 213 in PBMC. These genes showed differential expression (DE) patterns on analysis by visualization and integrated discovery (DAVID). The DE genes involved in the immune response included genes related to the inflammatory response (CD163), the innate immune response (TLR2, TLR4, MYD88, TIRAP), cell adhesion (CD34, SELE, SELL, SELP, ICAM-1, ICAM-2, VCAM-1), antigen processing and presentation (MHC protein complex) and angiogenesis (VEGF), together with genes encoding cytokines (interleukins). Five selected genes were validated by qRT-PCR analysis.We studied the response to infection with S. suis 2 strain SC19 by microarray analysis. Our findings confirmed some genes identified in previous studies and discovered numerous additional genes that potentially function in S. suis 2 infections in vivo. This new information will form the foundation of future investigations into the pathogenesis of S. suis.Streptococcus suis (S. suis 2) is an important pathogen of pigs that causes high mortality and is responsible for considerable economic loss to the porcine industry [1]. Serotype 2 is considered the most virulent form of the bacteria and is the serotype most frequently isolated from diseased animals [2]. S. suis 2 is also an emerging zoonotic agent and has been isolated from a wide range of mammalian species, including humans, who are often infected via skin wounds during contact with pigs and their products [3]. S. suis 2 is frequently isolated from asymptomatic pigs, especially adult pigs (young pigs are susceptible to the disease), which indicates that pigs can be carriers of S. suis 2. Two outbreaks in humans have been documented in China, in 1999 and 2005; hundreds of people were infected and 52 died. Human illness following S. suis infection has also been reported in Thailand [4], the United Kingdom [5], the Netherlands [6], Au
Characterization of porcine dendritic cell response to Streptococcus suis
Marie-Pier Lecours, Mariela Segura, Claude Lachance, Tufaria Mussa, Charles Surprenant, Maria Montoya, Marcelo Gottschalk
Veterinary Research , 2011, DOI: 10.1186/1297-9716-42-72
Abstract: Streptococcus suis is a major swine pathogen associated mainly with meningitis, although other pathologies have also been described such as septicemia with sudden death, endocarditis, arthritis, and pneumonia [1]. Among 35 serotypes described, serotype 2 is considered the most virulent and the most frequently isolated from both diseased pigs and humans. Consequently, most studies on virulence factors and the pathogenesis of infection have been carried out with this serotype [2]. Until recently, S. suis disease in humans has been considered as rare and only affecting people working with pigs or pork by-products. However, with a rising incidence in humans over the last years, S. suis is now considered as an important emerging zoonotic agent, especially in Asian countries, where S. suis has recently been identified as the leading cause of adult meningitis in Vietnam, the second in Thailand, and the third in Hong Kong. In 2005, an important outbreak occurred in China and resulted in 200 human cases with a fatality rate near 20% [1]. In humans, S. suis is mainly responsible for meningitis, septicemia and streptococcal toxic shock-like syndrome [1,3,4].Despite the increasing number of studies, the pathogenesis of the S. suis infection is still not completely understood and, to date, attempts to control the infection are hampered by the lack of an effective vaccine. The mechanisms involved in the host innate and adaptive immune responses toward S. suis as well as those used by S. suis to subvert these responses are unknown. Several virulence factors have been proposed to be involved in the pathogenesis of S. suis infection [5]. Among them, the capsular polysaccharide, which confers to the bacteria antiphagocytic properties, has been demonstrated as a critical virulence factor [2,6,7] and its structure was recently described [8]. In fact, non-encapsulated mutants were shown to be avirulent in mice and pig models of infection [2]. Among several proteins and enzymes, a hemoly
Streptococcus suis infection: Clinical manifestations
Dragojlovi? Julijana,Milo?evi? Branko,?a?i? Neda,Pelemi? Miomir
Medicinski Pregled , 2005, DOI: 10.2298/mpns0506236d
Abstract: Introduction Streptococcus suis is a bacterium causing a disease in pigs and rarely in humans. This zoonosis is mostly found as a sporadic disease in individuals that were in contact with the affected or infected pigs: farmers, veterinarians and workers engaged in fresh pork processing. It is assumed that the bacterium enters the body through a cut abrasion in the skin. Initially, the condition resembles a flu, followed by signs of bacteriemia and sepsis. The most frequent clinical manifestation of Streptococcus suis infection is meningitis, leading to hearing loss in over 75% of patients, and subsequent arthritis, endophtalmitis, endocarditis and pneumonia. Toxic shock syndrome with hemorhagic manifestations rarely develops. Material and methods This study included five male patients aged 22 to 63 years treated in the Intensive Care Unit of the Institute of Infectious and Tropical Diseases in Belgrade, due to Streptococcus suis infection. The aim of this study was to point to the existence of this bacteria in our environment, to describe clinical manifestations of the disease and to point out the importance of its prevention. Results All patients had epidemiological evidence of being in contact with pork meat. There were no data about diseased pigs. The estimated incubation period was 4 to 8 days. All patients had meningeal signs. Clinical symptoms included shivering, fever, vomiting, headache, malaise, vertigo and tinitus. Three patients presented with alerterd level of awareness. Four patients developed very severe bilateral hearing impairemnt, whereas one endophtalmtis and one developed endocarditis. The cerebrospinal fluid (CSF) was opalescent in four patients, and only one patient presented with clear CSF. CSF examination showed typical changes characeteristic for bacterial meningitis. Streptoccocus suis was isolated in CSF in all patients, and in one patient the bacteria was isolated in blood as well. All patients underwent treatment with II and III generation cephalosporins and one with one aminoglycosides. All patients were cured, but 4 of them developed sequelae like permanent sensorineural deafness and mild ataxia. Conclusions Streptococcus suis infection is present as a zoonosis in pigs, while humans are contracted occasionally, most frequently related to occupational risk. In cases with bacterial meningitis with sepsis and hearing loss, Streptococcus suis infections must be suspected. Effective prevention requires collaboration between epidemiologists, veterinarians and human medicine physicians. .
Streptococcus suis: an important zoonotic pathogen for human – prevention aspects
VG Papatsiros,D Vourvidis,AA Tzitzis,PS Meichanetsidis
Veterinary World , 2011,
Abstract: Streptococcus suis is a major porcine pathogen, causing economical health worldwide problems in the global swine industry. It is also emerging as a zoonotic agent capable of causing severe invasive disease in humans exposed to pigs or pork products. The most important clinical sign in swine and human is meningitis, but other pathological conditions have also been described. Serotype 2 is the most commonly associated with diseases in pigs and humans, and also the most frequently reported serotype isolated from diseased animals worldwide. The majority of human infection occurs in pork handlers, particularly in slaughterhouse workers and by minor wounds or skin abrasions contaminated by raw pork or viscera of pigs. Veterinarians should also be aware that a low but real risk may be present when manipulating S. suis-diseased animals that are probably shedding high numbers of this pathogen. Up today, in Greece there is no published epidemiological data for S. suis serotypes in swine herds and the zoonotic risk of S. suis infection in human with daily contact with pigs and pork meat. However, in our experience clinical forms of S. suis infection are common in most greek swine farms. The aim of this review study is to perform recent information about S. suis infection in swine and human, focus on zoonotic risk of this emerging pathogen and prevention strategies. [Vet. World 2011; 4(5.000): 216-221]
Sorotipagem de amostras de Streptococcus suis isoladas de suínos em granjas dos Estados de S?o Paulo, Minas Gerais e Paraná
Pagnani, Keila J.R.;Castro, Antonio F. Pestana;Gottschalk, Marcelo;Silveira, Wanderley D.;Nakazato, Gerson;
Pesquisa Veterinária Brasileira , 2002, DOI: 10.1590/S0100-736X2002000100002
Abstract: streptococcus suis infection in swine is common in all countries where hog production is well developed. this infection has been associated with bronchopneumonia, meningitis, arthritis, pericarditis, myocarditis, endocarditis, fibrinous polyserositis, septicaemia, rhinitis, and abortion. streptococcus suis has also been described as a pathogen for ruminants and humans. in brazil there are several clinical evidences about the existence of s. suis disease in pigs affecting more than 50% of farms in states of s?o paulo, minas gerais and paraná. in the present research 51 strains of s. suis isolated from piggeries of the states of s?o paulo, minas gerais and paraná were collected from different pathologies such as septicaemia, meningitis, arthritis and pneumonia and been recovered either in pure culture or as the predominant organism from porcine tissues. culture of specimens was carried out on 5% bovine blood agar plates incubated at 37°c for 24 hr. for the biochemical identification the a-hemolytic colonies of all capsulated isolates were submitted to various conventional tests, such as hydrolysis of arginine, voges-proskauer test, and production of acid from various carbohydrates (inulin, salicin, trehalose, lactose, sucrose, sorbitol, mannitol and glycerol). the strains were also tested for their ability to grow in the presence of 6,5% nacl and for the amylase production. in addition strains were tested by api strep 20 to confirm the identification of s.suis. for capsular typing only capsulated strains were typed by co-agglutination test, using antisera raised in rabbits against all reference strains from serotypes 1 to 8. strains belonging to other serotypes were also typed. the co-agglutination was used for serotyping and the capsular reaction test was carried out for measuring the potency of the prepared antisera. from the total of 51 examined strains the following results were obtained, with regard to serotyping: 30 (58,8%) were serotype 2, 11 (21,6%) were serot
Occurrence of antimicrobial resistance among bacterial pathogens and indicator bacteria in pigs in different European countries from year 2002 – 2004: the ARBAO-II study
Rene S Hendriksen, Dik J Mevius, Andreas Schroeter, Christopher Teale, Eric Jouy, Patrick Butaye, Alessia Franco, Andra Utinane, Alice Amado, Miguel Moreno, Christina Greko, Katharina DC St?rk, Christian Berghold, Anna-Liisa Myllyniemi, Andrzej Hoszowski, Marianne Sunde, Frank M Aarestrup
Acta Veterinaria Scandinavica , 2008, DOI: 10.1186/1751-0147-50-19
Abstract: Susceptibility data from 17,642 isolates of pathogens and indicator bacteria including Actinobacillus pleuropneumoniae, Streptococcus suis and Escherichia coli isolated from pigs were collected from fifteen European countries in 2002–2004.Data for A. pleuropneumoniae from infected pigs were submitted from five countries. Most of the isolates from Denmark were susceptible to all drugs tested with the exceptions of a low frequency of resistance to tetracycline and trimethoprim – sulphonamide.Data for S. suis were obtained from six countries. In general, a high level of resistance to tetracycline (48.0 – 92.0%) and erythromycin (29.1 – 75.0%) was observed in all countries whereas the level of resistance to ciprofloxacin and penicillin differed between the reporting countries. Isolates from England (and Wales), France and The Netherlands were all susceptible to penicillin. In contrast the proportion of strains resistant to ciprofloxacin ranged from 12.6 to 79.0% (2004) and to penicillin from 8.1 – 13.0% (2004) in Poland and Portugal.Data for E. coli from infected and healthy pigs were obtained from eleven countries. The data reveal a high level of resistance to tetracyclines, streptomycin and ampicillin among infected pigs whereas in healthy pigs the frequency of resistance was lower.Bacterial resistance to some antimicrobials was frequent with different levels of resistance being observed to several antimicrobial agents in different countries. The occurrence of resistance varied distinctly between isolates from healthy and diseased pigs, with the isolates from healthy pigs generally showing a lower level of resistance than those from diseased pigs.The study suggests that the choice of antimicrobials used for the treatment of diseased animals should preferably be based on knowledge of the local pattern of resistance.Antimicrobial agents are important drugs for the treatment of bacterial infections in pigs. Because of intensive pig rearing in Europe, large numbers of pig
Effect of Spatial Separation of Pigs on Spread of Streptococcus suis Serotype 9  [PDF]
Niels Dekker, Annemarie Bouma, Ineke Daemen, Don Klinkenberg, Leo van Leengoed, Jaap A. Wagenaar, Arjan Stegeman
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0061339
Abstract: The spread of an infectious agent in a population can be reduced by interfering in the infectiousness or susceptibility of individuals, and/or in their contact structure. The aim of this study was to quantify the effect of prevention of direct contact between infectious and susceptible pigs on the transmission of Streptococcus suis (S. suis). In three replicate experiments, S. suis-free pigs were housed in boxes either in pairs (25 pairs) or alone (15 pigs). The distance between the boxes was ±1 m. At 7 weeks of age, one pig of each pair was inoculated intranasally with S. suis serotype 9; the other pigs were exposed to S. suis by either direct (pairs) or indirect contact (individually housed pigs). Tonsillar brush and saliva swab samples from all pigs were collected regularly for 4 weeks post inoculation to monitor colonization with S. suis. All inoculated pigs became infected, and their pen mates became colonized within 2 days. Thirteen indirectly exposed pigs became positive within 7–25 days after exposure. The rate of direct transmission βdir was estimated to be 3.58 per pig per day (95% CI: 2.29–5.60). The rate of indirect transmission increased in time, depending on the cumulative number of days pigs tested positive for the presence of S. suis. The estimate β’ind was 0.001 (95% CI: 0.0006–0.0017) new infections per pig per day for each day that an infected pig was tested positive for S. suis. We conclude that prevention of direct contact reduces the rate at which susceptible pigs become colonized. Simulation studies using these parameters showed, however, that such intervention measure would not limit S. suis serotype 9 spread in a commercial pig farm to a relevant extent, implying that spatial separation of groups op pigs within a compartment would not be effective on a farm.
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