Investigation of genomic and pathogenicity characteristics of Streptococcus suis ST1 human strains from Guangxi Zhuang Autonomous Region (GX) between 2005 and 2020 in China

Streptococcus suis is a significant and emerging zoonotic pathogen. ST1 and ST7 strains are the primary agents responsible for S. suis human infections in China, including the Guangxi Zhuang Autonomous Region (GX). To enhance our understanding of S. suis ST1 population characteristics, we conducted an investigation into the phylogenetic structure, genomic features, and virulence levels of 73 S. suis ST1 human strains from GX between 2005 and 2020. The ST1 GX strains were categorized into three lineages in phylogenetic analysis. Sub-lineage 3-1a exhibited a closer phylogenetic relationship with the ST7 epidemic strain SC84. The strains from lineage 3 predominantly harboured 89K-like pathogenicity islands (PAIs) which were categorized into four clades based on sequence alignment. The acquirement of 89K-like PAIs increased the antibiotic resistance and pathogenicity of corresponding transconjugants. We observed significant diversity in virulence levels among the 37 representative ST1 GX strains, that were classified as follows: epidemic (E)/highly virulent (HV) (32.4%, 12/37), virulent plus (V+) (29.7%, 11/37), virulent (V) (18.9%, 7/37), and lowly virulent (LV) (18.9%, 7/37) strains based on survival curves and mortality rates at different time points in C57BL/6 mice following infection. The E/HV strains were characterized by the overproduction of tumour necrosis factor (TNF)-α in serum and promptly established infection at the early phase of infection. Our research offers novel insights into the population structure, evolution, genomic features, and pathogenicity of ST1 strains. Our data also indicates the importance of establishing a scheme for characterizing and subtyping the virulence levels of S. suis strains.

Molecular profile and epidemiological traits of Streptococcus suis isolated from diseased pigs in western Canada reveal multiple-serotype infection: Implications for disease control

Objective

Streptococcus suis is a major agent of disease in modern swine operations, linked to increased mortality, treatment costs, and secondary infections. Although it is ubiquitous in swine, only a fraction of pigs develop clinical disease. The goals of this study were to profile isolates obtained from diseased pigs in western Canada and to investigate potential associations with disease severity.

Procedure

Isolates of S. suis (n = 128) from 75 diagnostic submission and 63 premises were paired with epidemiological surveys completed by submitting practitioners (n = 22). Whole-genome sequencing was used to type isolates.

Results

The most prevalent serotypes identified were 1/2 (7.8%, 10/128), 2 (9.3%, 12/128), 3 (9.3%, 12/128), and 7 (7.8%, 10/128); and sequence types 28 (17%, 23/128) and 839 (14%, 19/128). There was no association between serotype or sequence type and organ source or barn location. Approximately 74% (14/19) of the premises had diseased animals colonized by > 1 S. suis serotype, but only 1 pig was simultaneously infected with multiple serotypes and sequence types. Serotype distribution from diseased pigs in western Canada differed from that of those in other geographic regions.

Conclusion

Infection of diseased pigs by multiple serotypes should be considered when disease control strategies are implemented. No association between S. suis type and isolation organ was identified.

Acute multiple brain infarctions associated with Streptococcus suis infection: a case report

Streptococcus suis is one of the most common zoonotic pathogens, in humans and can cause meningitis, endocarditis, arthritis and sepsis. Human cases of Streptococcus suis infection have been reported worldwide, and most of those cases occurred in Asia. Hearing loss is the most common sequela of Streptococcus suis meningitis. Streptococcus suis infection complicated with acute cerebral infarction has rarely been reported. Therefore, to provide a reference for this disease, we reported a case of acute multiple brain infarctions associated with Streptococcus suis infection. In our report, a 69yearold male patient had Streptococcus suis meningitis and sepsis, which were associated with multiple acute cerebral infarctions in the pons and bilateral frontotemporal parietal occipital lobes. After treatment, the patient exhibited cognitive impairment, dyspraxia and irritability. There are limited case reports of cerebral infarction associated with Streptococcus suis infection, and further research is needed to determine the best treatment method.

[Streptococcus suis meningitis]

Streptococcus suis (S. suis) is a globally prevalent swine pathogen, capable of generating infections in humans who were in contact with the animal or its raw meat. Clinical manifestations range from asymptomatic cases to systemic involvement, with low mortality, but with the possibility of leaving definitive sequelae such as ataxia and hearing loss. There are few case reports, due to lack of knowledge of the disease and its atypical presentation. The objective of this article is to report the case of a man with an occupational history of contact with pigs, who was admitted for meningitis and in whom the isolation of S. suis was obtained in cerebrospinal fluid and paired blood cultures; He completed antibiotic treatment adjusted to bacterial sensitivity, and was left with mild hearing loss as a consequence.

Distribution and characterization of Streptococcus suis serotypes isolated from January 2015 to June 2020 from diseased pigs in Québec, Canada

Streptococcus suis is one of the most important swine bacterial pathogens causing economic losses. This report presents the serotype distribution of S. suis recovered from diseased pigs in Québec from January 2015 to June 2020. Serotypes 1/2 and 2 predominated, followed by serotypes 7, 3, 5, 4, 9, 1, and 14. Compared to previously reported data, very few changes could be observed concerning the serotype distribution, indicating a relative stability. Half of the untypable isolates did not belong to the species S. suis sensu stricto, as determined by recN polymerase chain reaction. Less than 10% of "real S. suis" isolates were untypable. The genetic diversity of S. suis serotypes 1, 2, and 14, as analyzed by multilocus sequence typing, was mainly represented by sequence type (ST)1, ST28, ST25, and ST94. All ST1 isolates (considered highly virulent) belonged to either serotype 1 or 14.

Genomic and pathogenic investigations of Streptococcus suis serotype 7 population derived from a human patient and pigs

Streptococcus suis is one of the important emerging zoonotic pathogens. Serotype 2 is most prevalent in patients worldwide. In the present study, we first isolated one S. suis serotype 7 strain GX69 from the blood culture of a patient with septicemia complicated with pneumonia in China. In order to deepen the understanding of S. suis serotype 7 population characteristics, we investigated the phylogenetic structure, genomic features, and virulence of S. suis serotype 7 population, including 35 strains and 79 genomes. Significant diversities were revealed in S. suis serotype 7 population, which were clustered into 22 sequence types (STs), five minimum core genome (MCG) groups, and six lineages. Lineages 1, 3a, and 6 were mainly constituted by genomes from Asia. Genomes of Lineages 2, 3b, and 5a were mainly from Northern America. Most of genomes from Europe (41/48) were clustered into Lineage 5b. In addition to strain GX69, 13 of 21 S. suis serotype 7 representative strains were classified as virulent strains using the C57BL/6 mouse model. Virulence-associated genes preferentially present in highly pathogenic S. suis serotype 2 strains were not suitable as virulence indicators for S. suis serotype 7 strains. Integrative mobilizable elements were widespread and may play a critical role in disseminating antibiotic resistance genes of S. suis serotype 7 strains. Our study confirmed S. suis serotype 7 is a non-negligible pathotype and deepened the understanding of the population structure of S. suis serotype 7, which provided valuable information for the improved surveillance of this serotype.

Mutation rate dynamics reflect ecological change in an emerging zoonotic pathogen

Mutation rates vary both within and between bacterial species, and understanding what drives this variation is essential for understanding the evolutionary dynamics of bacterial populations. In this study, we investigate two factors that are predicted to influence the mutation rate: ecology and genome size. We conducted mutation accumulation experiments on eight strains of the emerging zoonotic pathogen Streptococcus suis. Natural variation within this species allows us to compare tonsil carriage and invasive disease isolates, from both more and less pathogenic populations, with a wide range of genome sizes. We find that invasive disease isolates have repeatedly evolved mutation rates that are higher than those of closely related carriage isolates, regardless of variation in genome size. Independent of this variation in overall rate, we also observe a stronger bias towards G/C to A/T mutations in isolates from more pathogenic populations, whose genomes tend to be smaller and more AT-rich. Our results suggest that ecology is a stronger correlate of mutation rate than genome size over these timescales, and that transitions to invasive disease are consistently accompanied by rapid increases in mutation rate. These results shed light on the impact that ecology can have on the adaptive potential of bacterial pathogens.

In vivo oxygen measurement in cerebrospinal fluid of pigs to determine physiologic and pathophysiologic oxygen values during CNS infections

During infection and inflammation, a reduced oxygen level clearly affects cellular functions. Oxygen levels during CNS infections are unknown. Here we established and evaluated an in vivo measurement system to characterize the oxygen level in parallel with bacterial numbers (CFU/mL), the cell number and pH level inside the CSF of healthy compared to Streptococcus suis-infected pigs. The animals were anesthetized over a seven-hour period with isoflurane in air/oxygen at physiologic arterial partial pressure of oxygen. Oxygen levels in CSF of anesthetized pigs were compared to euthanized pigs. The detected partial pressure of oxygen in the CSF remained constant in a range of 47-63 mmHg, independent of the infection status (bacterial or cell number). In contrast, the pH value showed a slight drop during infection, which correlated with cell and bacterial number in CSF. We present physiologic oxygen and pH values in CSF during the onset of bacterial meningitis.

Synergistic Effect of a Pleuromutilin Derivative with Tetracycline against Streptococcus suis In Vitro and in the Neutropenic Thigh Infection Model

Tetracycline (TET) has been widely used in the treatment of Streptococcus suis (S. suis) infection. However, it was found that the efficacy of many antibiotics in S. suis decreased significantly, especially tetracycline. In this study, GML-12 (a novel pleuromutilin derivative) was used in combination with TET against 12 S. suis isolates. In the checkerboard assay, the TET/GML-12 combination exhibited synergistic and additive effects against S. suis isolates (n = 12). In vitro time-killing assays and in vivo therapeutic experiments were used to confirm the synergistic effect of the TET/GML-12 combination against S. suis strains screened based on an FICI ≤ 0.5. In time-killing assays, the TET/GML-12 combination showed a synergistic effect or an additive effect against three isolates with a bacterial reduction of over 2.4-log10 CFU/mL compared with the most active monotherapy. Additionally, the TET/GML-12 combination displayed potent antimicrobial activity against four isolates in a mouse thigh infection model. These results suggest that the TET/GML-12 combination may be a potential therapeutic strategy for S. suis infection.

Streptococcus suis in Swedish grower pigs: occurrence, serotypes, and antimicrobial susceptibility

BACKGROUND

Streptococcus suis is a major cause of meningitis, arthritis, and pneumonia in pigs worldwide, and an emerging pathogen in humans. In Sweden, S. suis has previously received little attention but has in recent years become increasingly recognized as affecting the pig production. The aim of the present study was to investigate the occurrence, serotypes and antimicrobial susceptibility of S. suis in Swedish grower pigs from herds with and without reported S. suis associated disease, as well as possible associations between S. suis associated disease and selected environmental and production factors. Swab samples were taken from the tonsils of clinically healthy 8-13-week-old grower pigs from ten case herds and ten control herds. Isolates were cultured, identified using MALDI-TOF MS, and serotyped using latex agglutination. The antimicrobial susceptibility of 188 isolates was tested using broth microdilution. Production data was gathered and environmental parameters were measured on the farms.

RESULTS

Streptococcus suis was isolated from 95% of the sampled pigs in both the case and the control herds. Serotypes 3, 4, 5, 7, 9, 10, 11, 15, 16, and 17-34 were detected, although a majority of the isolates (81.5%) were non-typeable. There was less diversity among the serotypes isolated from the case herds than among those from the control herds; four and nine different serotypes, respectively. Isolates resistant to penicillin (3.8%) were reported for the first time in Sweden. Tetracycline resistance was common (88.4%). No association was noted between the production and the environmental factors investigated, and the carriership of S. suis.

CONCLUSIONS

The carriership of S. suis was found to be higher in clinically healthy Swedish pigs than previously estimated, and for the first time, the presence of Swedish isolates resistant to penicillin was reported. Many of the most commonly disease-associated serotypes, e.g. serotypes 2, 9, 3, and 7, were detected in healthy grower pigs although further studies are needed to investigate the virulence of these isolates.

Streptococcus suis-Associated Meningitis, Bali, Indonesia, 2014-2017

Streptococcus suis is an emerging agent of zoonotic bacterial meningitis in Asia. We describe the epidemiology of S. suis cases and clinical signs and microbiological findings in persons with meningitis in Bali, Indonesia, using patient data and bacterial cultures of cerebrospinal fluid collected during 2014-2017. We conducted microbiological assays using the fully automatic VITEK 2 COMPACT system. We amplified and sequenced gene fragments of glutamate dehydrogenase and recombination/repair protein and conducted PCR serotyping to confirm some serotypes. Of 71 cases, 44 were confirmed as S. suis; 29 isolates were serotype 2. The average patient age was 48.1 years, and 89% of patients were male. Seventy-seven percent of patients with confirmed cases recovered without complications; 11% recovered with septic shock, 7% with deafness, and 2% with deafness and arthritis. The case-fatality rate was 11%. Awareness of S. suis infection risk must be increased in health promotion activities in Bali.

The bacteriocin from the prophylactic candidate Streptococcus suis 90-1330 is widely distributed across S. suis isolates and appears encoded in an integrative and conjugative element

The Gram-positive α-hemolytic Streptococcus suis is a major pathogen in the swine industry and an emerging zoonotic agent that can cause several systemic issues in both pigs and humans. A total of 35 S. suis serotypes (SS) have been identified and genotyped into > 700 sequence types (ST) by multilocus sequence typing (MLST). Eurasian ST1 isolates are the most virulent of all S. suis SS2 strains while North American ST25 and ST28 strains display moderate to low/no virulence phenotypes, respectively. Notably, S. suis 90–1330 is an avirulent Canadian SS2-ST28 isolate producing a lantibiotic bacteriocin with potential prophylactic applications. To investigate the suitability of this strain for such purposes, we sequenced its complete genome using the Illumina and PacBio platforms. The S. suis 90–1330 bacteriocin was found encoded in a locus cargoed in what appears to be an integrative and conjugative element (ICE). This bacteriocin locus was also found to be widely distributed across several streptococcal species and in a few Staphylococcus aureus strains. Because the locus also confers protection from the bacteriocin, the potential prophylactic benefits of using this strain may prove limited due to the spread of the resistance to its effects. Furthermore, the S. suis 90–1330 genome was found to code for genes involved in blood survival, suggesting that strain may not be a benign as previously thought.

Molecular typing of Streptococcus suis strains isolated from diseased and healthy pigs between 1996-2016

Streptococcus suis is an economically important pathogen of pigs as well as a zoonotic cause of human disease. Serotyping is used for further characterization of isolates; some serotypes seem to be more virulent and more widely spread than others. This study characterizes a collection of German field isolates of Streptococcus suis from pigs dating from 1996 to 2016 with respect to capsular genes (cps) specific for individual serotypes and pathotype by multiplex PCR and relates results to the clinical background of these isolates. The most prominent finding was the reduction in prevalence of serotype-2/serotype-1/2 among invasive isolates during this sampling period, which might be attributed to widely implemented autogenous vaccination programs in swine against serotype 2 in Germany. In diseased pigs (systemically ill; respiratory disease) isolates of serotype-1/serotype-14, serotype-2/serotype-1/2, serotype 3 to 5 and 7 to 9 were most frequent while in carrier isolates a greater variety of cps types was found. Serotype-1/serotype-14 seemed to be preferentially located in joints, serotype 4 and serotype 3 in the central nervous system, respectively. The virulence associated extracellular protein factor was almost exclusively associated with invasive serotype-1/serotype-14 and serotype-2/serotype-1/2 isolates. In contrast, lung isolates of serotype-2/serotype-1/2 mainly harbored the gene for muramidase-released protein. Serotype 4 and serotype 9 isolates from clinically diseased pigs most frequently carried the muramidase-released protein gene and the suilysin gene. When examined by transmission electron microscopy all but one of the isolates which were non-typable by molecular and serological methods showed various amounts of capsular material indicating potentially new serotypes among these isolates. Given the variety of cps types/serotypes detected in pigs, not only veterinarians but also medical doctors should consider other serotypes than just serotype 2 when investigating potential human cases of Streptococcus suis infection.

Mutant prevention and minimum inhibitory concentration drug values for enrofloxacin, ceftiofur, florfenicol, tilmicosin and tulathromycin tested against swine pathogens Actinobacillus pleuropneumoniae, Pasteurella multocida and Streptococcus suis

Actinobacillus pleuropneumoniae, Pasteurella multocida and Streptococcus suis are prevalent bacterial causes of swine infections. Morbidity, mortality and positively impacting the financial burden of infection occurs with appropriate antimicrobial therapy. Increasing antimicrobial resistance complicates drug therapy and resistance prevention is now a necessity to optimize therapy and prolong drug life. Mutant bacterial cells are said to arise spontaneously in bacterial densities of 107-109 or greater colony forming units/ml. Antibiotic drug concentration inhibiting growth of the least susceptible cell in these high density populations has been termed the mutant prevention concentration (MPC). In this study MPC and minimum inhibitory concentration (MIC) values of ceftiofur, enrofloxacin, florfenicol, tilmicosin and tulathromycin were determined against the swine pathogens A. pleuropneumoniae, P.multocida and S. suis. The following MIC90/MPC90 values (mg/L) for 67 A. pleuropneumoniae and 73 P. multocida strains respectively were as follows: A. pleuropneumoniae 0.031/0.5, ≤0.016/0.5, 0.5/2, 4/32, 2/32; P. multocida 0.004/0.25, 0.016/0.125, 0.5/0.5, 8/16, 0.5/1. For 33 S. suis strains, MIC90 values (mg/L) respectively were as follows: 1, 0.25, 4, ≥8 and ≥8. A total of 16 S. suis strains with MIC values of 0.063-0.5 mg/L to ceftiofur and 0.25-0.5 mg/L to enrofloxacin were tested by MPC; MPC values respectively were 0.5 and 1 mg/L respectively. MPC concentrations provide a dosing target which may serve to reduce amplification of bacterial subpopulations with reduced antimicrobial susceptibility. Drug potency based on MIC90 values was ceftiofur > enrofloxacin >florfenicol = tulathromycin > tilmicosin; based on MPC90 values was enrofloxacin > ceftiofur > tulathromycin > florfenicol ≥ tilmicosin.

Novel Streptococcus suis Sequence Type 834 among Humans, Madagascar

Two cases of meningitis caused by Streptococcus suis occurred in Madagascar, 1 in 2015 and 1 in 2016. We report the characterization of the novel sequence type, 834, which carried the mrp+/sly+/epf+ virulence marker and a mutation G→T at position 174, leading to a substitution mutS1 to mutS284.

Genomic epidemiological investigation of a Streptococcus suis outbreak in Guangxi, China, 2016

In June 2016, a Streptococcus suis outbreak occurred in Guangxi, China. We determined the genetic characteristics of six clinically isolated strains by serotyping, PCR, and whole-genome sequencing, performing genome epidemiology analysis on these and 961 public available S. suis genomes. We also classified the first sequence type ST665 human case. Sporadic and outbreak cases were distinguished by whole-genome sequencing and phylogenomics. This approach could help to prevent and control S. suis epidemics in Guangxi and the wider region.

An epidemiological study of Streptococcus suis serotypes of pigs in Ontario determined by a multiplex polymerase chain reaction

The purpose of the study was to identify the serotypes of Streptococcus suis from tonsil swabs in clinically ill and healthy pigs in Ontario using a multiplex polymerase chain reaction (PCR) method. Although 22 different serotypes were identified, most isolates were S. suis-like bacteria or untypable.

Human Case of Streptococcus suis Disease, Ontario, Canada

We report a case of Streptococcus suis human disease in Ontario, Canada, caused by a serotype 2 strain genotypically similar to those commonly isolated from pigs in North America. Initially, the isolate was misidentified as a viridans group Streptococcus. Human S. suis infections may be underdiagnosed in North America.

Factors contributing to mortality during a Streptoccocus suis outbreak in nursery pigs

The objective of this study was to investigate the association between sow- and litter-level factors with mortality in a swine nursery barn experiencing a severe Streptococcus suis disease outbreak. All-cause mortality data from a 300-sow farrow-to-finish herd was analyzed using a Cox's regression model. The data were recorded over 6 months and included 24 cohorts, 297 sows, 295 litters, and 2779 piglets with an average of 14.4% post-weaning mortality. If the sows had 2 litters within the study period and pigs from their first litter experienced mortality, then pigs from their subsequent litter had a decreased risk of mortality [hazard ratio (HR) = 0.34, P < 0.05]. Pigs were more likely to experience mortality if at least 1 additional littermate experienced mortality (HR = 9.22, P = 0.001). Under conditions of this study, the results suggest mechanisms related to sow immunity and within-litter spread that could have contributed to the risk of mortality during the S. suis outbreak.

Streptococcus suis: a re-emerging pathogen associated with occupational exposure to pigs or pork products. Part II - Pathogenesis

Streptococcus suis is a re-emerging zoonotic pathogen that may cause severe disease, mostly meningitis, in pigs and in humans having occupational contact with pigs and pork, such as farmers, slaughterhose workers and butchers. The first stage of the pathogenic process, similar in pigs and humans, is adherence to and colonisation of mucosal and/or epithelial surface(s) of the host. The second stage is invasion into deeper tissue and extracellular translocation of bacterium in the bloodstream, either free in circulation or attached to the surface of monocytes. If S. suis present in blood fails to cause fatal septicaemia, it is able to progress into the third stage comprising penetration into host's organs, mostly by crossing the blood-brain barrier and/or blood-cerebrospinal fluid barrier to gain access to the central nervous system (CNS) and cause meningitis. The fourth stage is inflammation that plays a key role in the pathogen esis of both systemic and CNS infections caused by S. suis. The pathogen may induce the overproduction of pro-inflammatory cytokines that cause septic shock and/or the recruitment and activation of different leukocyte populations, causing acute inflammation of the CNS. Streptococcus suis can also evoke - through activation of microglial cells, astrocytes and possibly other cell types - a fulminant inflammatory reaction of the brain which leads to intracranial complications, including brain oedema, increased intracranial pressure, cerebrovascular insults, and deafness, as a result of cochlear sepsis. In all stages of the pathogenic process, S. suis interacts with many types of immunocompetent host's cells, such as polymorphonuclear leukocytes, mononuclear macrophages, lymphocytes, dendritic cells and microglia, using a range of versatile virulence factors for evasion of the innate and adaptive immune defence of the host, and for overcoming environmental stress. It is estimated that S. suis produces more than 100 different virulence factors that could be classified into 4 groups: surface components or secreted elements, enzymes, transcription factors or regulatory systems and transporter factors or secretion systems. A major virulence factor is capsular polysaccharide (CPS) that protects bacteria from phagocytosis. However, it hampers adhesion to and invasion of host's cells, release of inflammatory cytokines and formation of the resistant biofilm which, in many cases, is vital for the persistence of bacteria. It has been demonstrated that the arising by mutation unencapsulated S. suis clones, which are more successful in penetration to and propagation within the host's cells, may coexist in the organism of a single host together with those that are encapsulated. Both 'complementary' clones assist each other in the successful colonization of host's tissues and persistence therein. S. suis has an open pan-genome characterized by a frequent gene transfer and a large diversity. Of the genetic determinants of S. suis pathogenicity, the most important are pathogenicity islands (PAI), in particular, a novel DNA segment of 89 kb length with evident pathogenic traits that has been designated as 89K PAI. It has been estimated that more than one-third of the S. suis virulence factors is associated with this PAI. It has been proved that the virulent S. suis strains possess smaller genomes, compared to avirulent ones, but more genes associated with virulence. Overall, the evolution of the species most probably aims towards increased pathogenicity, and hence the most significant task of the current research is an elaboration of a vaccine, efficient both for humans and pigs.

Streptococcus suis Serotype 2 Capsule In Vivo

Many Streptococcus suis isolates from porcine endocarditis in slaughterhouses have lost their capsule and are considered avirulent. However, we retrieved capsule- and virulence-recovered S. suis after in vivo passages of a nonencapsulated strain in mice, suggesting that nonencapsulated S. suis are still potentially hazardous for persons in the swine industry.

Identification of Streptococcus suis Meningitis through Population-Based Surveillance, Togo, 2010-2014

During 2010-2014, we enrolled 511 patients with suspected bacterial meningitis into surveillance in 2 districts of northern Togo. We identified 15 persons with Streptococcus suis infection; 10 had occupational contact with pigs, and 12 suffered neurologic sequelae. S. suis testing should be considered in rural areas of the African meningitis belt.

Streptococcus suis: a re-emerging pathogen associated with occupational exposure to pigs or pork products. Part I - Epidemiology

Streptococcus suis (ex Elliot 1966, Kilpper-Bälz & Schleifer 1987) is a facultatively anaerobic Gram-positive ovoid or coccal bacterium surrounded by a polysaccharide capsule. Based on the antigenic diversity of the capsule, S. suis strains are classified serologically into 35 serotypes. Streptococcus suis is a commensal of pigs, commonly colonizing their tonsils and nasal cavities, mostly in weaning piglets between 4-10 weeks of age. This species occurs also in cattle and other mammals, in birds and in humans. Some strains, mostly those belonging to serotype 2, are also pathogenic for pigs, as well as for other animals and humans. Meningitis is the primary disease syndrome caused by S. suis, both in pigs and in humans. It is estimated that meningitis accounted for 68.0% of all cases of human disease reported until the end of 2012, followed by septicaemia (including life-threatening condition described as 'streptococcal toxic shock-like syndrome' - STSLS), arthritis, endocarditis, and endophthalmitis. Hearing loss and/or ves tibular dysfunction are the most common sequelae after recovery from meningitis caused by S. suis, occurring in more than 50% of patients. In the last two decades, the number of reported human cases due to S. suis has dramatically increased, mostly due to epidemics recorded in China in 1998 and 2005, and the fulminant increase in morbidity in the countries of south-eastern Asia, mostly Vietnam and Thailand. Out of 1,642 cases of S. suis infections identified between 2002-2013 worldwide in humans, 90.2% occurred in Asia, 8.5% in Europe and 1.3% in other parts of the globe. The human disease has mostly a zoonotic and occupational origin and occurs in pig breeders, abattoir workers, butchers and workers of meat processing facilities, veterinarians and meat inspectors. Bacteria are transmitted to workers by close contact with pigs or pig products, usually through contamination of minor cuts or abrasions on skin of hands and/or arms, or by pig bite. A different epidemiologic situation occurs in the Southeast Asian countries where most people become infected by habitual consumption of raw or undercooked pork, blood and offal products in the form of traditional dishes. Prevention of S. suis infections in pigs includes vaccination, improvement in pig-raising conditions, disinfection and/or fumigation of animal houses, and isolation of sick animals at the outbreak of disease. Prevention of human infections comprises: protection of skin from pig bite or injury with sharp tools by people occupationally exposed to pigs and pig products, prompt disinfection and dressing of wounds and abrasions at work, protection of the respiratory tract by wearing appropriate masks or repirators, consulting a doctor in the case of febrile illness after exposure to pigs or pork meat, avoidance of occupations associated with exposure to pigs and pork by immunocompomised people, avoidance of consumption of raw pork or pig blood, adequate cooking of pork, and health education.

Case report: two human Streptococcus suis infections in Borneo, Sabah, Malaysia

BACKGROUND

Streptococcus Suis (S.suis) is increasingly being recognised as a potentially preventable emerging zoonotic infection in humans with a global distribution. It is a major cause of meningitis especially among those in contact with pigs and has also been associated with a toxic shock syndrome.

CASE PRESENTATIONS

We report the first two human cases from Sabah, Borneo, Malaysia which expands the global reach of this important pathogen. Here, we illustrate their epidemiological risk factors, clinical presentation and resulting sequelae of both patients.

CONCLUSION

The continued public health threat of zoonotic infections such as S.suis, highlights the need for accurate epidemiological surveillance, regulation of pig farming, slaughtering and continued advocacy of best practices for pork preparation and consumption.

Detection of Multiple Parallel Transmission Outbreak of Streptococcus suis Human Infection by Use of Genome Epidemiology, China, 2005

Streptococcussuis sequence type 7 emerged and caused 2 of the largest human infection outbreaks in China in 1998 and 2005. To determine the major risk factors and source of the infections, we analyzed whole genomes of 95 outbreak-associated isolates, identified 160 single nucleotide polymorphisms, and classified them into 6 clades. Molecular clock analysis revealed that clade 1 (responsible for the 1998 outbreak) emerged in October 1997. Clades 2–6 (responsible for the 2005 outbreak) emerged separately during February 2002–August 2004. A total of 41 lineages of S.suis emerged by the end of 2004 and rapidly expanded to 68 genome types through single base mutations when the outbreak occurred in June 2005. We identified 32 identical isolates and classified them into 8 groups, which were distributed in a large geographic area with no transmission link. These findings suggest that persons were infected in parallel in respective geographic sites.

Isolation and partial characterization of Streptococcus suis from clinical cases in cattle

Sixteen isolates of gram-positive, coccoid bacteria were obtained from clinical cases of diverse conditions in cattle and identified as Streptococcus suis using 16S ribosomal DNA gene sequencing and other bacterial identification methods. None of the isolates could be assigned to any of the known S. suis capsular types. Virulence-associated gene profiling that targeted muramidase-released protein, extracellular protein factor, suilysin, 89-kb pathogenicity island, and arginine deiminase ( arcA) genes were negative except for 1 isolate that was arcA positive. The arcA-positive isolate caused severe widespread lesions, including multiorgan suppurative and hemorrhagic inflammation in the meninges, lung, liver, spleen, lymph nodes, and serosae of heart and intestines. The other isolates were primarily associated with meningitis, bronchopneumonia, and multifocal acute necrotizing hepatitis. The isolates differed from each other by 4-6 fragments when examined by pulsed-field gel electrophoresis, indicating they are possibly related. The isolates were susceptible to ampicillin, penicillin, and tiamulin. Resistance was noted to sulfadimethoxine (93%), oxytetracycline (86%), chlortetracycline (86%), neomycin (67%), tilmicosin (47%), clindamycin (47%), enrofloxacin (33%), gentamicin (13%), florfenicol (7%), trimethoprim-sulfamethoxazole (7%), and spectinomycin (53%). Multi-drug resistance (defined as resistance to at least 1 agent in 3 or more antimicrobial classes) was detected in 67% of the isolates. The pathology observations provide evidence that S. suis may be an important pathogen of bovine calves. S. suis is an agent that clinical bacteriology laboratories should consider when dealing with cases involving cattle.

Comparative Genome Analyses of Streptococcus suis Isolates from Endocarditis Demonstrate Persistence of Dual Phenotypic Clones

Many bacterial species coexist in the same niche as heterogeneous clones with different phenotypes; however, understanding of infectious diseases by polyphenotypic bacteria is still limited. In the present study, encapsulation in isolates of the porcine pathogen Streptococcus suis from persistent endocarditis lesions was examined. Coexistence of both encapsulated and unencapsulated S. suis isolates was found in 26 out of 59 endocarditis samples. The isolates were serotype 2, and belonged to two different sequence types (STs), ST1 and ST28. The genomes of each of the 26 pairs of encapsulated and unencapsulated isolates from the 26 samples were sequenced. The data showed that each pair of isolates had one or more unique nonsynonymous mutations in the cps gene, and the encapsulated and unencapsulated isolates from the same samples were closest to each other. Pairwise comparisons of the sequences of cps genes in 7 pairs of encapsulated and unencapsulated isolates identified insertion/deletions (indels) ranging from one to 104 bp in different cps genes of unencapsulated isolates. Capsule expression was restored in a subset of unencapsulated isolates by complementation in trans with cps expression vectors. Examination of gene content common to isolates indicated that mutation frequency was higher in ST28 pairs than in ST1 pairs. Genes within mobile genetic elements were mutation hot spots among ST28 isolates. Taken all together, our results demonstrate the coexistence of dual phenotype (encapsulated and unencapsulated) bacterial clones and suggest that the dual phenotypes arose independently in each farm by means of spontaneous mutations in cps genes.

Effects of cello-oligosaccharide on intestinal microbiota and epithelial barrier function of weanling pigs

A total of 144 piglets (Duroc × Landrace × Yorkshire; average initial weight of 6.13 kg weaned at 21 ± 1 d age) were allotted to 4 treatments for 2 wk, each of which had 6 pens with 6 pigs per pen. After the feeding experiment, 6 pigs per treatment were slaughtered to investigate the effects of cello-oligosaccharide (COS) on intestinal microbiota and epithelial barrier function. The COS was added to the basal diet at 0, 1.5, 3.0, and 4.5 g/kg diet at the expense of corn, respectively. Plasma -lactate, diamine oxidase (DAO), and the Ussing chamber technique were used to determine the intestinal barrier function. 16S rRNA-based methods were used for intestinal microbiota analysis. The results showed that incremental levels of COS had no effect ( > 0.05) on growth performance. Incremental levels of COS increased lactobacilli in jejunal and colonic contents ( < 0.05); decreased in jejunal contents ( < 0.05) and and in colonic contents ( < 0.05); reduced plasma DAO (linear, = 0.013, and quadratic, = 0.037); increased jejunal mucosa DAO (linear, = 0.003, and quadratic, = 0.008); decreased fluorescein isothiocyanate dextran 4 kDa flux of jejunum and colon ( < 0.05); and increased transepithelial electrical resistance (TER) in colon ( < 0.05), claudin-1 protein expression in jejunal mucosa (linear, = 0.001, and quadratic, = 0.003), and protein expressions of claudin-1 and zonula occludens-1 (ZO-1) in colonic mucosa linearly ( = 0.001 and = 0.001, respectively) and quadratically ( = 0.001 and = 0.002, respectively). The results indicated that the improved microbial ecosystem in the presence of COS might contribute to improvement in intestinal barrier function and tight junction proteins. Results also showed that the appropriate dietary COS supplementation level was 3.0 g/kg in weaned pig diets under our trial conditions.

[Isolation and characterization of a Streptococcus suis serotype 9 from a wild cat]

OBJECTIVE

Streptococcus suis (S. suis) is an emerging zoonotic pathogenic bacterium capable of infecting piglets and human and with sporadic infections in a variety of mammalian species. The aim of this study is to investigate the prevalence of S. suis in wild cats.

METHODS

We isolated an S. suis strain from a wild cat. We tested the serotype of the isolated strain by anti-serum agglutination and PCR. We determined the sequence type (ST) of the isolated strain by multilocus sequence typing tests (MLST). We constructed the 16S rRNA phylogenetic tree of the isolation and S. suis strains in NCBI database to demonstrated genetic relationship of different strains. We measured the antibiotic resistance of the isolated strain by triple disk diffusion method. We detected the virulence of the isolated strain by mice infection experiments.

RESULTS

We isolated an S. suis strain m70 from a wild cat, which belongs to serotype 9. MLST showed that m70 fell into a new ST. The 16S rRNA phylogenetic tree of m70 and S. suis strains in NCBI database demonstrated that m70 was in a separate cluster. m70 was resistant to tetracycline, intermediate to erythromycin, and sensitive to ampicillin, corresponding to clinical S. suis isolates in China. The mortality of mice infected with 10(8) CFU of m70 was achieved 60%-80% (3/5-4/5). The mean LD50 of mice infected with m70 was 5.1 x 10(7) CFU, while the mean LD50 of virulent S. suis strain HA9801 was 3.9 x 10(7) CFU. There is no significant difference between the LD50 of the two strains (P < 0.05).

CONCLUSION

We isolated an S. suis strain from a wild cat, which belongs to the prevalent serotype and was a virulent strain, indicating the potential of transmission of S. suis from wild cats to humans, especially some prevalent serotype strains.

Streptococcus suis Meningitis: A Systematic Review and Meta-analysis

Background

Streptococcus suis is the most common cause of meningitis in pork consuming and pig rearing countries in South-East Asia. We performed a systematic review of studies on S. suis meningitis to define the clinical characteristics, predisposing factors and outcome.

Methodology

Studies published between January 1, 1980 and August 1, 2015 were identified from main literature databases and reference lists. Studies were included if they were written in West-European languages and described at least 5 adult patients with S. suis meningitis in whom at least one clinical characteristic was described.

Findings

We identified 913 patients with S. suis meningitis included in 24 studies between 1980 and 2015. The mean age was 49 years and 581 of 711 patients were male (82%). Exposure to pigs or pork was present in 395 of 648 patients (61%) while other predisposing factors were less common. 514 of 528 patients presented with fever (97%), 429 of 451 with headache (95%), 462 of 496 with neck stiffness (93%) and 78 of 384 patients (20%) had a skin injury in the presence of pig/pork contact. The case fatality rate was 2.9% and hearing loss was a common sequel occurring in 259 of 489 patients (53%). Treatment included dexamethasone in 157 of 300 (52%) of patients and was associated with reduced hearing loss in S. suis meningitis patients included in a randomized controlled trial.

Conclusion

S. suis meningitis has a clear association with pig and pork contact. Mortality is low, but hearing loss occurs frequently. Dexamethasone was shown to reduce hearing loss.

Meningitis is a common manifestation of Streptococcus suis infection. S. suis is endemic in pork consuming and pig rearing countries. We systematically reviewed the clinical characteristics, predisposing factors and outcome of S. suis meningitis. We identified 913 patients included in 24 studies, with a mean age of 49 years and a majority of male patients (82%). Exposure to pigs or pork was present in 61%, with a skin injury being present in 20%. Fever was present in 97% of patients, headache in 95%, neck stiffness in 93%. The mortality was 2.9% and hearing loss was common occurring in 53% of patients. Dexamethasone was associated with reduced hearing loss.

Streptococcus suis in employees and the environment of swine slaughterhouses in São Paulo, Brazil: Occurrence, risk factors, serotype distribution, and antimicrobial susceptibility

Streptococcus suis is an important pathogen in the swine industry. This article is the first to report the occurrence, risk factors, serotype distribution, and antimicrobial susceptibility of S. suis recovered from employees and environmental samples of swine slaughterhouses in Brazil. Tonsillar swabs from all 139 pig-slaughtering employees and 261 environmental swabs were collected for detection of S. suis and serotyping by monoplex and multiplex polymerase chain reaction, respectively. Antimicrobial susceptibility was determined by the disk-diffusion method. Although S. suis was not detected in any of the tested employees, it was isolated from 25% of the environmental samples. Significant differences (P < 0.05) in the occurrence of S. suis were observed between slaughterhouses and between areas of low, medium, and high risk. The most frequent serotypes were 4 and 29, each accounting for 12% of the isolates, followed by 5, 12, 21, and 31, each accounting for 6%. High rates of susceptibility to the antimicrobials doxycycline (100%), ceftiofur (94%), ampicillin (81%), and cephalexin (75%) were observed. However, multidrug resistance was observed in all the isolates. Because S. suis is present in the environment of swine slaughterhouses, on carcasses and knives, as well as on the hands of employees in all areas, all employees are at risk of infection.

Multi-Etiological Nature of Tuberculosis-Like Lesions in Condemned Pigs at the Slaughterhouse

Tuberculosis-like lesions (TBL) in pigs have been associated with microorganisms other than mycobacteria. In this work a histopathological and microbiological evaluation of TBL in pigs is shown. A total of 352 samples belonging to 171 pigs totally condemned at slaughterhouse due to generalized TBL were sampled and selected for analysis. Pyogranulomatous (56.2%) and granulomatous lesions (20.2%) were observed in all analysed organs. Most of the granulomas observed in both lymph nodes and lungs belonged to more advanced stages of development (stages III and IV) whereas in the liver and the spleen most of lesions belonged to intermediate stages (stages II and III). Different microorganisms were simultaneously detected from TBL in the 42.7% of the animals. Mycobacterium tuberculosis complex (MTC) (38%), coryneform bacteria (40.3%) and streptococci (28.1%) were the main groups of microorganisms detected after bacteriological analysis, with Trueperella pyogenes and Streptococcus suis as the most frequently isolated species. Mycobacteria belonging to MTC were the most frequently detected pathogens in granulomatous and pyogranulomatous lesions in submandibular lymph nodes (32.7%) and coryneform bacteria were the microorganisms more frequently isolated from lungs (25.9%) and spleen samples (37.2%). These results may provide new insights into the pathogenesis and diagnosis of this pathology. The importance of coryneform bacteria and streptococci in such processes must be evaluated in future studies.

Genetic diversity of Streptococcus suis isolated from three pig farms of China obtained by acquiring antibiotic resistance genes

BACKGROUND

Acquiring antibiotic resistance genes may change an organism's genetic characteristics and the effect of antibiotics, resulting in a rapid transmission of microbial pathogens. The objectives of this experiment were to identify the features of Streptococcus suis (S. suis) isolated from three pig farms in China which are geographically isolated.

RESULTS

Among the isolates, 56.52% were sequence type 7 (ST7), followed by ST1 (26.09%), indicating that ST7 prevails in China, as revealed by multi-locus sequence typing (MLST). Statistical analysis indicated an association between geography, sequence types and antibiotic resistance genotypes. 66.67% of the isolates in Sichuan province presented a (ermB(-) + mefA(-) + tetO(-) + tetM(-)) + ST7 type. The tetM(+) +ST7 type was the most prevalent in Jiangsu province, whereas the strains from Hebei province had a phenotype ermB(+) +tetO(+) +ST1 (63.64%). Pulsed-field gel electrophoresis (PGFE) pattern A2 with 100% similarity reflected the clonal dissemination between Sichuan and Jiangsu provinces. Strains carrying or not carrying antibiotic resistance genes presented different PFGE patterns in Hebei province.

CONCLUSION

ST7 is widespread in many regions of China and a clonal dissemination occurred between Sichuan and Jiangsu provinces in diseased pigs. However, ST1 strains with macrolide and tetracycline resistance (ermB(+) +tetO(+) +ST1) isolated from a farm in Hebei province demonstrated that the genetic diversity was contributed by horizontal acquiring of ermB and tetO carrying elements.

Investigation of Pathogenesis of H1N1 Influenza Virus and Swine Streptococcus suis Serotype 2 Co-Infection in Pigs by Microarray Analysis

Swine influenza virus and Streptococcus suis are two important contributors to the porcine respiratory disease complex, and both have significant economic impacts. Clinically, influenza virus and Streptococcus suis co-infections in pigs are very common, which often contribute to severe pneumonia and can increase the mortality. However, the co-infection pathogenesis in pigs is unclear. In the present study, co-infection experiments were performed using swine H1N1 influenza virus and Streptococcus suis serotype 2 (SS2). The H1N1-SS2 co-infected pigs exhibited more severe clinical symptoms, serious pathological changes, and robust apoptosis of lungs at 6 days post-infection compared with separate H1N1 and SS2 infections. A comprehensive gene expression profiling using a microarray approach was performed to investigate the global host responses of swine lungs against the swine H1N1 infection, SS2 infection, co-infection, and phosphate-buffered saline control. Results showed 457, 411, and 844 differentially expressed genes in the H1N1, SS2, and H1N1-SS2 groups, respectively, compared with the control. Noticeably, genes associated with the immune, inflammatory, and apoptosis responses were highly overexpressed in the co-infected group. Pathway analysis indicated that the cytokine–cytokine receptor interactions, MAPK, toll-like receptor, complement and coagulation cascades, antigen processing and presentation, and apoptosis pathway were significantly regulated in the co-infected group. However, the genes related to these were less regulated in the separate H1N1 and SS2 infection groups. This observation suggested that a certain level of synergy was induced by H1N1 and SS2 co-infection with significantly stronger inflammatory and apoptosis responses, which may lead to more serious respiratory disease syndrome and pulmonary pathological lesion.

Isolation of Streptococcus suis from 2 lambs with a history of lameness

Streptococcus suis was isolated postmortem from 2 lambs with a history of lameness. Identity of S. suis was confirmed by species-specific polymerase chain reaction (PCR) and by 16S rRNA gene sequencing. One isolate was untypable by serotyping and non-encapsulated, while the other isolate was serotype 33. The lambs had come from the same farm, and there was no evidence of contact between the lambs and pigs. Although the natural niche for S. suis is considered to be the pig, a wide range of host species may be affected by this pathogen.

Surveillance of antimicrobial resistance in clinical isolates of Pasteurella multocida and Streptococcus suis from Ontario swine

Susceptibility results for Pasteurella multocida and Streptococcus suis isolated from swine clinical samples were obtained from January 1998 to October 2010 from the Animal Health Laboratory at the University of Guelph, Guelph, Ontario, and used to describe variation in antimicrobial resistance (AMR) to 4 drugs of importance in the Ontario swine industry: ampicillin, tetracycline, tiamulin, and trimethoprim-sulfamethoxazole. Four temporal data-analysis options were used: visualization of trends in 12-month rolling averages, logistic-regression modeling, temporal-scan statistics, and a scan with the "What's strange about recent events?" (WSARE) algorithm. The AMR trends varied among the antimicrobial drugs for a single pathogen and between pathogens for a single antimicrobial, suggesting that pathogen-specific AMR surveillance may be preferable to indicator data. The 4 methods provided complementary and, at times, redundant results. The most appropriate combination of analysis methods for surveillance using these data included temporal-scan statistics with a visualization method (rolling-average or predicted-probability plots following logistic-regression models). The WSARE algorithm provided interesting results for quality control and has the potential to detect new resistance patterns; however, missing data created problems for displaying the results in a way that would be meaningful to all surveillance stakeholders.

Synthesis of multi-fullerenes encapsulated palladium nanocage, and its application in electrochemiluminescence immunosensors for the detection of Streptococcus suis Serotype 2

A novel functionalized material is synthesized using surface-decorated fullerene (C60) to encapsulate hollow and porous palladium nanocages (PdNCs), and is applied to fabricate an electrochemiluminescence (ECL) immunosensor for the detection of Streptococcus suis Serotype 2 (SS2). PdNCs with hollow interiors and porous walls are prepared using a galvanic replacement reaction between silver nanocubes and metal precursor salts. Then, C60 reacts with L-cysteine (L-Cys) to form L-Cys functionalized C60 (C60-L-Cys), which has a better biocompatibility, conductivity, and hydrophilicity compared to C60 and possesses abundant -SH groups on the surface. Because of the special interaction between -SH and PdNCs, the obtained C60-L-Cys is adsorbed around the PdNCs to form an interesting structure with multiple spheres encapsulating the cage. The resultant functionalized material (C60 -L-Cys-PdNCs) has a high specific surface area, good electrocatalytic ability, and efficient photocatalytic activity, and is used to construct an ECL immunosensor for the detection of SS2. The ECL signal amplified strategy is performed by using the novel coreactant (C60-L-Cys) and in situ generation of O2 thus creating the S2O8(2-)-O2 ECL system. As a result, a wide linear detection range of 0.1 pg mL(-1) to 100 ng mL(-1) is acquired with a relatively low detection limit of 33.3 fg mL(-1).

Characterisation of Streptococcus suis isolates from wild boars (Sus scrofa)

Wild boar are widely distributed throughout the Iberian Peninsula and can carry potentially virulent strains of Streptococcus suis. The objective of this study was to determine the prevalence of S. suis in wild boars from two large geographical regions of Spain. Serotypes 1, 2, 7 and 9 identified were further genetically characterised by virulence-associated genotyping, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) to determine the population structure of S. suis carried by these animals. Streptococcus suis was isolated from 39.1% of the wild boars examined: serotype 9 was the most frequently isolated (12.5%), followed by serotype 1 (2.5%). Serotype 2 was rarely isolated (0.3%). Eighteen additional serotypes were identified indicating wide diversity of this pathogen within the wild boar population. This heterogeneity was confirmed by PFGE and MLST analyses and the majority of isolates exhibited the virulence-associated genotype mrp-/epf-/sly-. The results of this study highlight that the carriage of S. suis by wild boars is commonplace. However, MLST data indicate that these isolates are not related to prevalent clonal complexes ST1, ST16, ST61 and ST87 typically associated with infection of pigs or humans in Europe.

Antimicrobial activity of nisin against the swine pathogen Streptococcus suis and its synergistic interaction with antibiotics

Streptococcus suis serotype 2 is known to cause severe infections in pigs, including meningitis, endocarditis and pneumonia. Furthermore, this bacterium is considered an emerging zoonotic agent. Recently, increased antibiotic resistance in S. suis has been reported worldwide. The objective of this study was to evaluate the potential of nisin, a bacteriocin of the lantibiotic class, as an antibacterial agent against the pathogen S. suis serotype 2. In addition, the synergistic activity of nisin in combination with conventional antibiotics was assessed. Using a plate assay, the nisin-producing strain Lactococcus lactis ATCC 11454 proved to be capable of inhibiting the growth of S. suis (n=18) belonging to either sequence type (ST)1, ST25, or ST28. In a microdilution broth assay, the minimum inhibitory concentration (MIC) of purified nisin ranged between 1.25 and 5 μg/mL while the minimum bactericidal concentration (MBC) was between 5 and 10 μg/mL toward S. suis. The use of a capsule-deficient mutant of S. suis indicated that the presence of this polysaccharidic structure has no marked impact on susceptibility to nisin. Following treatment of S. suis with nisin, transmission electron microscopy observations revealed lysis of bacteria resulting from breakdown of the cell membrane. A time-killing curve showed a rapid bactericidal activity of nisin. Lastly, synergistic effects of nisin were observed in combination with several antibiotics, including penicillin, amoxicillin, tetracycline, streptomycin and ceftiofur. This study brought clear evidence supporting the potential of nisin for the prevention and treatment of S. suis infections in pigs.

[Septic arthritis caused by Streptococcus suis]

Streptococcus suis is a global endemic swine pathogen. S. suis can cause meningitis, endocarditis and severe sepsis in humans, who are exposed to swine. Human infection with S. suis was first reported in 1968, since then, human infections have been sporadic although an outbreak in China counted 215 cases. In a rare case of disseminated arthritis we found that correct clinical diagnosis was difficult due to unspecific symptomatology and slow growing bacterial culture. However, conducting thorough examinations is crucial, and if treated correctly the outcome is favourable.