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

Streptococcus suis meningitis in China: a case report

Introduction

Streptococcus suis is one of the porcine pathogens that have recently emerged as a pathogen capable of causing zoonoses in some humans. Patients infected with S. suis can present with sepsis, meningitis, or arthritis. Compared to common pathogens, such as Meningococcus, Streptococcus pneumoniae, and Haemophilus influenzae, S. suis infections in humans have been reported only rarely.

Methods

This case report described a 57-year-old man who presented with impaired consciousness and fever following several days of backache. He was a butcher who worked in an abattoir and had wounded his hands 2 weeks prior. The patient was dependent on alcohol for almost 40 years. S. suis was detected in the cerebrospinal fluid by metagenomic next-generation sequencing. Although he received adequate meropenem and low-dose steroid therapy, the patient suffered from bilateral sudden deafness after 5 days of the infection. The final diagnosis was S. suis meningitis and sepsis.

Results

The patient survived with hearing loss in both ears and dizziness at the 60-day follow-up.

Discussion

We reported a case of S. suis infection manifested as purulent meningitis and sepsis. Based on literature published worldwide, human S. suis meningitis shows an acute onset and rapid progression in the nervous system. Similar to bacterial meningitis, effective antibiotics, and low-dose steroids play important roles in the treatment of human S. suis meningitis.

Clinical presentation, management, and outcome of suspected central nervous system infections in Indonesia: a prospective cohort study

BACKGROUND

Little is known about the etiology, clinical presentation, management, and outcome of central nervous system (CNS) infections in Indonesia, a country with a high burden of infectious diseases and a rising prevalence of HIV.

METHODS

We included adult patients with suspected CNS infections at two referral hospitals in a prospective cohort between April 2019 and December 2021. Clinical, laboratory, and radiological assessments were standardized. We recorded initial and final diagnoses, treatments, and outcomes during 6 months of follow-up.

RESULTS

Of 1051 patients screened, 793 were diagnosed with a CNS infection. Patients (median age 33 years, 62% male, 38% HIV-infected) presented a median of 14 days (IQR 7-30) after symptom onset, often with altered consciousness (63%), motor deficits (73%), and seizures (21%). Among HIV-uninfected patients, CNS tuberculosis (TB) was most common (60%), while viral (8%) and bacterial (4%) disease were uncommon. Among HIV-infected patients, cerebral toxoplasmosis (41%) was most common, followed by CNS TB (19%), neurosyphilis (15%), and cryptococcal meningitis (10%). A microbiologically confirmed diagnosis was achieved in 25% of cases, and initial diagnoses were revised in 46% of cases. In-hospital mortality was 30%, and at six months, 45% of patients had died, and 12% suffered from severe disability. Six-month mortality was associated with older age, HIV, and severe clinical, radiological and CSF markers at presentation.

CONCLUSION

CNS infections in Indonesia are characterized by late presentation, severe disease, frequent HIV coinfection, low microbiological confirmation and high mortality. These findings highlight the need for earlier disease recognition, faster and more accurate diagnosis, and optimized treatment, coupled with wider efforts to improve the uptake of HIV services.

Molecular Epidemiology of Underreported Emerging Zoonotic Pathogen Streptococcus suis in Europe

Streptococcus suis, a zoonotic bacterial pathogen circulated through swine, can cause severe infections in humans. Because human S. suis infections are not notifiable in most countries, incidence is underestimated. We aimed to increase insight into the molecular epidemiology of human S. suis infections in Europe. To procure data, we surveyed 7 reference laboratories and performed a systematic review of the scientific literature. We identified 236 cases of human S. suis infection from those sources and an additional 87 by scanning gray literature. We performed whole-genome sequencing to type 46 zoonotic S. suis isolates and combined them with 28 publicly available genomes in a core-genome phylogeny. Clonal complex (CC) 1 isolates accounted for 87% of typed human infections; CC20, CC25, CC87, and CC94 also caused infections. Emergence of diverse zoonotic clades and notable severity of illness in humans support classifying S. suis infection as a notifiable condition.

A Bacterial mRNA-Lysis-Mediated Cargo Release Vaccine System for Regulated Cytosolic Surveillance and Optimized Antigen Delivery

Engineered vector-based in vivo protein delivery platforms have made significant progress for both prophylactic and therapeutic applications. However, the lack of effective release strategies results in foreign cargo being trapped within the vector, restricting the provision of significant performance benefits and enhanced therapeutic results compared to traditional vaccines. Herein, the development of a Salmonella mRNA interferase regulation vector (SIRV) system is reported to overcome this challenge. The genetic circuits are engineered that (1) induce self-lysis to release foreign antigens into target cells and (2) activate the cytosolic surveillance cGAS-STING axis by releasing DNA into the cytoplasm. Delayed synthesis of the MazF interferase regulates differential mRNA cleavage, resulting in a 36-fold increase in the delivery of foreign antigens and modest activation of the inflammasome, which collectively contribute to the marked maturation of antigen-presenting cells (APCs). Bacteria delivering the protective antigen SaoA exhibits excellent immunogenicity and safety in mouse and pig models, significantly improving the survival rate of animals challenged with multiple serotypes of Streptococcus suis. Thus, the SIRV system enables the effective integration of various modular components and antigen cargos, allowing for the generation of an extensive range of intracellular protein delivery systems using multiple bacterial species in a highly efficient manner.

Meningitis and sepsis caused by Streptococcus suis in an elderly woman: A CARE-compliant case report

RATIONALE

Streptococcus suis (S suis)-associated infections are uncommon but life-threatening diseases. The clinical manifestations vary from general symptoms of bacterial infection to fatal meningitis. The clinical manifestation and routine diagnostic testing is not specific enough to obtain well-time diagnosis.

PATIENT CONCERNS AND DIAGNOSIS

We report a case of meningitis and sepsis caused by S suis infection. A 70-year-old woman presented to our emergency department with generalized pain. After hospital admission, her condition rapidly deteriorated to fever, intracranial hypertension, and disturbance of consciousness. Examination of the blood and cerebrospinal fluid with metagenomic next-generation sequencing and bacterial cultures revealed S suis infection.

INTERVENTIONS AND OUTCOMES

After anti-infection therapy with meropenem and vancomycin, the patient recovered and was discharged from the hospital with no residual effects.

LESSONS

Human infections with S suis are extremely rare. If clinicians encounter a patient with fever, disturbance of consciousness, and intracranial hypertension, especially those who have been exposed to raw pork, S suis infection should be considered. Metagenomic next-generation sequencing can be a useful adjunct for the rapid diagnosis of S suis infection and aid in the planning of clinical treatment. Meanwhile, public health awareness is necessary to limit the risk of S suis infection.

Co-Existence of Oxazolidinone Resistance Genes cfr(D) and optrA on Two Streptococcus parasuis Isolates from Swine

This study was performed to investigate the presence and characteristics of the oxazolidinone resistance genes optrA and cfr(D) in Streptococcus parasuis. In total, 36 Streptococcus isolates (30 Streptococcus suis isolates, 6 Streptococcus parasuis isolates) were collected from pig farms in China in 2020-2021, using PCR to determine the presence of optrA and cfr. Then, 2 of the 36 Streptococcus isolates were further processed as follows. Whole-genome sequencing and de novo assembly were employed to analyze the genetic environment of the optrA and cfr(D) genes. Conjugation and inverse PCR were employed to verify the transferability of optrA and cfr(D). The optrA and cfr(D) genes were identified in two S. parasuis strains named SS17 and SS20, respectively. The optrA of the two isolates was located on chromosomes invariably associated with the araC gene and Tn554, which carry the resistance genes erm(A) and ant(9). The two plasmids that carry cfr(D), pSS17 (7550 bp) and pSS20-1 (7550 bp) have 100% nucleotide sequence identity. The cfr(D) was flanked by GMP synthase and IS1202. The findings of this study extend the current knowledge of the genetic background of optrA and cfr(D) and indicate that Tn554 and IS1202 may play an important role in the transmission of optrA and cfr(D), respectively.

Establishment and Application of an Indirect ELISA for the Detection of Antibodies to Porcine Streptococcus suis Based on a Recombinant GMD Protein

S. suis is an important zoonotic pathogen from sick and recessive carrier pigs that poses a serious threat to animal husbandry production and public health. It usually causes horizontal transmission among pigs. The morbidity and mortality of this disease are very high. Human infection is caused through direct or indirect contact with sick pigs. The two large-scale outbreaks in China were due to the outbreak of S. suis on pig farms, which spread to human infection; thus, detecting S. suis in pig herds is crucial. At present, the commercial S. suis ELISA type 2 kits on the market can only detect single serotypes, high probabilities of interaction reactions, and biosafety risks when using inactivated S. suis as an antigen. Phosphate-3-glyceraldehyde dehydrogenase (GAPDH), muramidase-released protein (MRP), and dihydrolipoamide dehydrogenase (DLDH) are important S. suis type 2, S. suis type 7, and S. suis type 9 protective antigens. This study purified the GMD protein (B-cell-dominant epitopes of GAPDH, MRP, and DLDH antigens) and used a diverse combination of dominant epitopes of the multiple different antigens as coated antigens, improving the sensitivity and safety of the indirect ELISA experiments. An indirect ELISA method (GMD-ELISA) was developed for detecting S. suis antibodies. The antigen-antibody response was optimized using checkerboard titration. The results of testing using ELISA for Salmonella enterica (S. enterica), Escherichia coli (E. coli), Staphylococcus aureus (SA), and Streptococcus pyogenes (S. pyogenes) were all negative, indicating that this method had strong specificity. The results were still positive when the dilution ratio of S. suis-positive serum reached 1:6, 400, thus indicating that the method had high sensitivity. The results of the reproducibility assay for indirect ELISA showed that the intra-assay coefficient of variation and the inter-assay coefficient of variation were less than 10%, indicating that the method had good repeatability. We investigated the seroprevalence of S. suis in 167 serum samples collected in East China, and 33.5% of the samples were positive for antibodies against S. suis, indicating that the prevalence of S. suis is high in pig farms in Eastern China. The novel GMD-ELISA is a convenient, sensitive, and specific diagnostic method that provides technical support for rapid diagnosis and epidemiological investigation.

ETIOLOGY AND CLINICAL FEATURES OF BACTERIAL MENINGITIS IN ADULTS AT NATIONAL HOSPITAL FOR TROPICAL DISEASES, PERIOD 2015 – 2018

To evaluate the etiology and clinical features of bacterial meningitis (BM) in adults during 2015-2018 in Vietnam, a retrospective study using 102 patients was performed at the National Hospital of Tropical Diseases. BM occurred throughout the year, peaking in July-September. A total of 80.4% BM patients were males over 40 years old. The proportion of patients with underlying diseases was 41.2% and those in contact with pigs or pork products was 30.4%. Common manifestations include stiff neck, Kernig's sign, headache, fever/hypothermia, and altered consciousness. The cerebrospinal fluid (CSF) had high protein concentration (median: 3.2 g/L, range: 1.3-6.2) and leukocytes (median: 1,312 cell/mm³, range: 234-2,943). Moreover, 29.4% meningitis cases were associated with septicemia. Streptococcus suis was the main cause (72.5%), followed by Pneumococcus (6.8%) and a few other bacteria. Factors associated with S. suis risk were male sex (OR: 8.29, 95% CI: 2.83-24.33), over 40 years old (OR: 3.55, 95% CI: 1.28-9.87), drinking habits (OR: 3.78, 95% CI: 1.03-13.72), headache (OR: 6.19, 95% CI: 2.17-17.65), fever/hypothermia (OR: 5.17, 95% CI: 1.97-13.56) and ≥2.0 ng/mL procalcitonin (OR: 2.72, 95% CI: 1.07-6.89). Education on S. suis and nosocomial infection prevention, as well as pneumococcal vaccination use, should be continued.

Inhibitory Effect of Monoterpenoid Glycosides Extracts from Peony Seed Meal on Streptococcus suis LuxS/AI-2 Quorum Sensing System and Biofilm

Streptococcus suis LuxS/AI-2 quorum sensing system regulates biofilm formation, resulting in increased pathogenicity and drug resistance, and diminished efficacy of antibiotic treatment. The remaining peony seed cake after oil extraction is rich in monoterpenoid glycosides, which can inhibit the formation of bacterial biofilm. In this study, we investigated the effect of seven major monocomponents (suffruticosol A, suffruticosol B, suffruticosol C, paeonifloin, albiflorin, trans-ε-viniferin, gnetin H) of peony seed meal on minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of S. suis. The results showed that the MICs of the seven single components were all greater than 200 μg/mL, with no significant bacteriostatic and bactericidal advantages. Crystal violet staining and scanning electron microscope observation showed that the seven single components had a certain inhibitory effect on the biofilm formation ability of S. suis at sub-MIC concentration. Among them, the ability of paeoniflorin to inhibit biofilm was significantly higher than that of the other six single components. AI-2 signaling molecules were detected by bioreporter strain Vibrio harvey BB170. The detection results of AI-2 signal molecules found that at 1/2 MIC concentration, paeoniflorin significantly inhibited the production of S. suis AI-2 signal, and the inhibitory effect was better than that of the other six single components. In addition, molecular docking analysis revealed that paeoniflorin had a significant binding activity with LuxS protein compared with the other six single components. The present study provides evidence that paeoniflorin plays a key role in the regulation of the inhibition of S. suis LuxS/AI-2 system and biofilm formation in peony seed meal.

The value of next-generation sequencing for the diagnosis of Streptococcus suis meningitis

OBJECTIVE

The aim of this study was to investigate the value of next-generation sequencing for the diagnosis of Streptococcus suis meningitis.

METHODS

Patients with meningitis in the Department of Neurology of the Hainan General Hospital were recruited and divided into a next-generation sequencing group and a control group. In the next-generation sequencing group, we used the next-generation sequencing method to detect the specific pathogenic bacteria in the patients. In the control group, we used the cerebrospinal fluid bacterial culture method to detect the specific pathogenic bacteria in the patients.

RESULTS

A total of 28 participants were recruited for this study, with 14 participants in each group. The results showed similarities in both the average age and average course of the disease between the two groups (p>0.05). The white blood cell count, percentage of neutrophils, and level of C-reactive protein in the next-generation sequencing group were significantly higher than those in the control group (p<0.05). There were similarities in both the temperature and intracranial pressure between the two groups (p>0.05). In the next-generation sequencing group, all patients (100%) were detected as having had the S. suis meningitis infection by next-generation sequencing, while only 6 (43%) patients in the control group had been detected as having the S. suis meningitis infection by cerebrospinal fluid bacterial culture.

CONCLUSIONS

The positive detection rate of S. suis by the next-generation sequencing method was significantly higher compared with using a cerebrospinal fluid bacterial culture. Therefore, the next-generation sequencing method is valuable for the diagnosis of S. suis meningitis and is worthy of clinical application.

Streptococcus suis meningitis complicated with acute cerebral infarction: A case report

A case of suppurative meningitis complicated with acute cerebral infarction caused by Streptococcus suis was reported to provide reference for the diagnosis and treatment of Streptococcus suis infection. The diagnosis, treatment, follow-up and epidemiological materials in the case of suppurative meningitis complicated with acute cerebral infarction caused by Streptococcus suis in Heyuan People’s Hospital were reviewed, and the relevant literature was reviewed. The clinical manifestations of this case were headache and fever, which progressed rapidly. After effective anti-infection treatment, the patient improved and discharged from the hospital, but there was profound hearing impairment.

Bacteriophage-Mediated Risk Pathways Underlying the Emergence of Antimicrobial Resistance via Intrageneric and Intergeneric Recombination of Antibiotic Efflux Genes Across Natural populations of Human Pathogenic Bacteria

Antimicrobial resistance continues to be a significant and growing threat to global public health, being driven by the emerging drug-resistant and multidrug-resistant strains of human and animal bacterial pathogens. While bacteriophages are generally known to be one of the vehicles of antibiotic resistance genes (ARGs), it remains largely unclear how these organisms contribute to the dissemination of the genetic loci encoding for antibiotic efflux pumps, especially those that confer multidrug resistance, in bacteria. In this study, the in-silico recombination analyses provided strong statistical evidence for bacteriophage-mediated intra-species recombination of ARGs, encoding mainly for the antibiotic efflux proteins from the MF superfamily, as well as from the ABC and RND families, in Salmonella enterica, Staphylococcus aureus, Staphylococcus suis, Pseudomonas aeruginosa, and Burkholderia pseudomallei. Events of bacteriophage-driven intrageneric recombination of some of these genes could be also elucidated among Bacillus thuringiensis, Bacillus cereus and Bacillus tropicus natural populations. Moreover, we could also reveal the patterns of intergeneric recombination, involving the MF superfamily transporter-encoding genetic loci, induced by a Mycobacterium smegmatis phage, in natural populations of Streptomyces harbinensis and Streptomyces chartreusis. The SplitsTree- (fit: 100; bootstrap values: 92.7-100; Phi p ≤ 0.2414), RDP4- (p ≤ 0.0361), and GARD-generated data strongly supported the above genetic recombination inferences in these in-silico analyses. Thus, based on this pilot study, it can be suggested that the above mode of bacteriophage-mediated recombination plays at least some role in the emergence and transmission of multidrug resistance across a fairly broad spectrum of bacterial species and genera including human pathogens.

Salmonella enterica serovar Choleraesuis vector delivering a dual-antigen expression cassette provides mouse cross-protection against Streptococcus suis serotypes 2, 7, 9, and 1/2

A universal vaccine protecting against multiple serotypes of Streptococcus suis is urgently needed to improve animal welfare and reduce the consumption of antibiotics. In this study, a dual antigen expression cassette consisting of SS2-SaoA and SS9-Eno was delivered by a recombinant Salmonella Choleraesuis vector to form the vaccine candidate rSC0016(pS-SE). SaoA and Eno were simultaneously synthesized in rSC0016(pS-SE) without affecting the colonization of the recombinant vector in the lymphatic system. In addition, the antiserum of mice immunized with rSC0016(pS-SE) produced a broader and potent opsonophagocytic response against multiple serotypes of S. suis. Finally, rSC0016(pS-SE) provided mice with a 100% protection against a lethal dose of parent S. suis serotype 2 and serotype 9, and provided 90% and 80% protection against heterologous S. suis serotype 7 or 1/2. These values were significantly higher than those obtained with rSC0016(pS-SaoA) or rSC0016(pS-Eno). Together, this study serves as a foundation for developing a universal vaccine against multiple serotypes of S. suis.

Sociocultural Factors Influencing Human Streptococcus suis Disease in Southeast Asia

The public health systems of Southeast Asian countries are financially challenged by a comparatively higher incidence of human S. suis infections than other geographical areas. Efforts to improve practices in production settings, including improved meat inspection regulations, prevention of the slaughtering of non-healthy pigs, and enhanced hygiene practices at processing facilities, along with improvements in the pork supply chain, all appear promising for reducing food cross-contamination with S. suis. However, opportunities for intervention at the societal level are also needed to effect changes, as population behaviors such as the consumption of raw pork, blood, and offal products are important contributors to the increased incidence of human S. suis disease in Southeast Asia. A plethora of factors are associated with the consumption of these high-risk dishes, including traditional culture and knowledge, shared beliefs, socio-economic level, and personal attitudes associated with gender and/or marital status. Education and intervention in behavioral attitudes that are sensible to cultural practices and traditions may provide additional means to reduce the burden of S. suis human disease in Southeast Asia.

Spinal canal infection caused by Streptococcus suis in human: a case report

Background

Streptococcus suis is an emerging zoonotic pathogen that mainly causes meningitis, sepsis, arthritis, endocarditis, and endophthalmitis in human. To the best of our knowledge, Spinal canal infection caused by Streptococcus suis has rarely been reported.

Case presentation

Here we report a case of spinal canal infection caused by Streptococcus suis in a 50-year-old male patient. The patient had a history of close contact with sick pigs days before disease onset. Initially he presented with headache and fever. After admission, the patient began to experience lower back pain, which led physicians to perform a lumber puncture. Meta-genomic next generation sequencing helped identify Streptococcus suis in the cerebrospinal fluid. MRI imaging indicated a spinal canal infection caused by Streptococcus suis.

Conclusions

Spinal canal infection is an uncommon disease of Streptococcus suis infection. This case report indicates that people presented with fever, headache and lower back pain should also be suspected as Streptococcus suis infection, especially for those who have had a history of sick pig contact.

Streptococcus suis spondylodiscitis: 2 new cases and a literature review

INTRODUCTION

Streptococcus suis (S. suis) infection is poorly described zoonosis in our country, which is related with exposure to pigs or their meat. The most common clinical presentation is meningitis, while spine's involvement is rare.

METHODS

We report 2 cases of S. suis infection and perform a systematic review of the articles published on S. suis spondylodiscitis between January 1994 and May 2020 with the aim of defining the clinical characteristics, predisposing factors and evolution.

RESULTS

17 cases are described, 76.5% males with a mean age of 57.6 years, generally without associated underlying disease. Enolism was a factor present in 17.6%. 70.6% had exposure to pigs or their meat and 20% hand injuries. The mean duration of symptoms was 10.2 days and the most affected segment was the lumbar level. 70.6% had meningitis. All were treated with beta-lactams with an average duration of 53.2 days. There was a recurrence and none died.

CONCLUSION

There are few cases of S. suis spondylodiscitis in the literature. When occurs, it is associated with another type of infection in most cases. They present a good response to medical treatment and a good prognosis.

Association of Common Zoonotic Pathogens With Concentrated Animal Feeding Operations

Animal farming has intensified significantly in recent decades, with the emergence of concentrated animal feeding operations (CAFOs) in industrialized nations. The congregation of susceptible animals in CAFOs can lead to heavy environmental contamination with pathogens, promoting the emergence of hyper-transmissible, and virulent pathogens. As a result, CAFOs have been associated with emergence of highly pathogenic avian influenza viruses, hepatitis E virus, Escherichia coli O157:H7, Streptococcus suis, livestock-associated methicillin-resistant Staphylococcus aureus, and Cryptosporidium parvum in farm animals. This has led to increased transmission of zoonotic pathogens in humans and changes in disease patterns in general communities. They are exemplified by the common occurrence of outbreaks of illnesses through direct and indirect contact with farm animals, and wide occurrence of similar serotypes or subtypes in both humans and farm animals in industrialized nations. Therefore, control measures should be developed to slow down the dispersal of zoonotic pathogens associated with CAFOs and prevent the emergence of new pathogens of epidemic and pandemic potential.

A rare case of meningitis and septicemia caused by Streptococcus suis in a woman without a history of live pig contact or eating raw pork

Streptococcus suis (S. suis) is a zoonotic pathogen that primarily inhabits the upper respiratory tract of pigs. Therefore, pigs that carry these pathogens are the major source of infection. Most patients are infected through contact with live pigs or unprocessed pork products and eating uncooked pork. S. Suis mainly causes sepsis and meningitis. The disease has an insidious onset and rapid progress. The patient becomes critically ill and the mortality is high. In this case report, we described a rare case of S. suis isolated from a middle-aged woman in Jinhua City, Zhejiang Province, China, who did not have any contact with live pigs and had not eaten uncooked pork. S. Suis was isolated from both the patient’s blood and cerebrospinal fluid samples.

Clinical study on the diagnosis of porcine streptococcal meningitis with negative blood and cerebrospinal fluid culture by next-generation sequencing

Background

Streptococcus suis (Ss) is a Gram-positive and anaerobic zoonotic pathogen that is susceptible to all populations and can cause meningitis, septicemia, endocarditis and arthritis in humans.

Methods

In this study, patients with meningitis who were admitted to our hospital with negative blood and cerebrospinal fluid culture were divided into a next-generation sequencing group and a control group. In the next-generation sequencing group, we used the next-generation sequencing method to detect pathogenic bacteria in the patients’ cerebrospinal fluid. In the control group, we used blood and cerebrospinal fluid bacterial culture method to detect pathogenic bacteria in the patients' cerebrospinal fluid. The detection rates of pathogenic bacteria in the cerebrospinal fluid of the two groups were compared and analyzed.

Results

A total of 18 patients were included in this study, including 8 patients in the next-generation sequencing group and 10 patients in the control group. The mean age (P = 0.613) and mean disease duration (P = 0.294) were similar in both groups. Patients in the next-generation sequencing group had a leukocyte count of 13.13 ± 4.79 × 10⁹, a neutrophil percentage of 83.39 ± 10.36%, and a C-reactive protein level of 134.95 ± 107.69 mg/L. Patients in the control group had a temperature of 38.32 ± 1.07, a leukocyte count of 8.00 ± 2.99 × 10⁹, and a neutrophil percentage of 74.61 ± 8.89%, and C-reactive protein level was 4.75 ± 6.8 mg/L. The statistical results showed that the leukocytes (P = 0.013) and C-reactive protein levels (P = 0.001) were significantly higher in the patients of the next-generation sequencing group than in the control group. No statistically significant differences were seen in body temperature and neutrophil percentage between the two groups (P > 0.05). The incidence of intracranial pressure and meningeal irritation signs were similar in the two groups (P > 0.05). The detection rate of Streptococcus suis in the cerebrospinal fluid of patients in the next-generation sequencing group was 100%, and the detection rate of Streptococcus suis in the cerebrospinal fluid of the control group was 0%.

Conclusion

The detection rate of Streptococcus suis infection in cerebrospinal fluid by next-generation sequencing was significantly higher than that by blood and cerebrospinal fluid bacterial culture. Therefore, the diagnosis of porcine streptococcal meningitis by next-generation sequencing method is worthy of clinical promotion and application.

Streptococcus suis Encodes Multiple Allelic Variants of a Phase-Variable Type III DNA Methyltransferase, ModS, That Control Distinct Phasevarions

Streptococcus suis is a causative agent of meningitis, polyarthritis, and polyserositis in swine, and it is a major cause of zoonotic meningitis in humans. Here, we investigate epigenetic gene regulation in S. suis by multiple phasevarions controlled by the phase-variable type III DNA methyltransferase ModS.

Streptococcus suis is a significant cause of bacterial meningitis in humans, particularly in Southeast Asia, and is a leading cause of respiratory and invasive disease in pigs. Phase-variable DNA methyltransferases, associated with restriction-modification (R-M) systems, are a source of epigenetic gene regulation, controlling the expression of multiple genes. These systems are known as phasevarions (phase-variable regulons) and have been characterized in many host-adapted bacterial pathogens. We recently described the presence of a Type III DNA methyltransferase in S. suis, ModS, which contains a simple sequence repeat (SSR) tract within the open reading frame of the modS gene and which differed in length between individual strains. We also observed that multiple allelic variants of the modS gene were present in a population of S. suis isolates. Here, we demonstrate that a biphasic ON-OFF switching of expression occurs in the two most common ModS alleles, ModS1 and ModS2, and that switching is dependent on SSR tract length. Furthermore, we show using single-molecule real-time (SMRT) sequencing that ModS1 and ModS2 are active methyltransferases in S. suis. ON-OFF switching of each ModS allele results in the regulation of distinct phasevarions, with the ModS2 phasevarion impacting growth patterns and antibiotic resistance. This is the first demonstration of a phase-variable Type III DNA methyltransferase in a Gram-positive organism that controls a phasevarion. Characterizing the phenotypic effects of phasevarions in S. suis is key to understanding pathogenesis and the development of future vaccines.

IMPORTANCEStreptococcus suis is a causative agent of meningitis, polyarthritis, and polyserositis in swine, and it is a major cause of zoonotic meningitis in humans. Here, we investigate epigenetic gene regulation in S. suis by multiple phasevarions controlled by the phase-variable Type III DNA methyltransferase ModS. This is the first characterized example of a Type III R-M system regulating a phasevarion in a Gram-positive organism. We demonstrate that biphasic ON-OFF switching of ModS expression results in differences in bacterial growth and antibiotic resistance. Understanding the effects of ModS phase variation is required to determine the stably expressed antigenic repertoire of S. suis, which will direct and inform the development of antimicrobial treatments and vaccines against this important pathogen.

Mode of action and structural modelling of the interaction of formononetin with suilysin

AIMS

Suilysin is a critical pore-forming virulence factor of Streptococcus suis that has been demonstrated to substantially contribute to its pathogenicity. We have demonstrated that formononetin alleviates S. suis infection both in vivo and in vitro by targeting suilysin. However, the molecular mechanism of the effect is unclear. Our aim was to determine the molecular mechanism of the effect of formononetin on suilysin.

METHODS AND RESULTS

The mechanism of interaction between formononetin and suilysin was investigated by molecular modelling. The results indicated that formononetin was bound at the junction of domain two and domain four of suilysin. The binding free energy values indicated that the A415, Y412, E414, N413, T61, T62 and G416 residues are critical for this binding, this observation was confirmed by the changes in the flexibility of these residues and the distances between these residues and formononetin. The inhibitory effect of formononetin on the pore-forming activity of suilysin, binding constant and binding free energy were significantly decreased by site-specific mutagenesis of Y412 and N413. Finally, we analysed the spatial configuration of suilysin before and after formononetin binding, the results indicated that the binding changed the conformation of suilysin, especially the angle between domain two and domain four, resulting in the disruption of cholesterol binding to suilysin and in the loss of pore-forming activity.

CONCLUSIONS

Formononetin is located at the junction of domain two and domain four of suilysin, and Y412 and N413 play critical roles in the binding. Formononetin binding changes the angle between domain two and domain four of suilysin, resulting in the loss of the pore-inducing activity of suilysin.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work will promote the application of formononetin to combat S. suis infections and may contribute to the development of new inhibitors or modification of existing inhibitors.

Streptococcus suis spondylodiscitis: 2 new cases and a literature review

INTRODUCTION

Streptococcus suis (S. suis) infection is poorly described zoonosis in our country, which is related with exposure to pigs or their meat. The most common clinical presentation is meningitis, while spinés involvement is rare.

METHODS

We report 2 cases of S. suis infection and perform a systematic review of the articles published on S. suis spondylodiscitis between January 1994 and May 2020 with the aim of defining the clinical characteristics, predisposing factors and evolution.

RESULTS

17 cases are described, 76.5% males with a mean age of 57.6 years, generally without associated underlying disease. Enolism was a factor present in 17.6%. 70.6% had exposure to pigs or their meat and 20% hand injuries. The mean duration of symptoms was 10.2 days and the most affected segment was the lumbar level. 70.6% had meningitis. All were treated with beta-lactams with an average duration of 53.2 days. There was a recurrence and none died.

CONCLUSION

There are few cases of S. suis spondylodiscitis in the literature. When occurs, it is associated with another type of infection in most cases. They present a good response to medical treatment and a good prognosis.

Pathogenic characteristics of sputum and bronchoalveolar lavage fluid samples from patients with lower respiratory tract infection in a large teaching hospital in China: a retrospective study

BACKGROUND

Lower respiratory tract infection (LRIs) is very common both in terms of community-acquired infection and hospital-acquired infection. Sputum and bronchoalveolar lavage fluid (BALF) are the most important specimens obtained from patients with LRI. The choice of antibiotic with which to treat LRI usually depends on the antimicrobial sensitivity of bacteria isolated from sputum and BALF. However, differences in the antimicrobial sensitivity of pathogens isolated from sputum and BALF have not been evaluated.

METHODS

A retrospective study was conducted to analyze the differences between sputum and BALF samples in terms of pathogen isolation and antimicrobial sensitivity in hospitalized patients with LRI.

RESULTS

Between 2013 and 2015, quality evaluation of sputum samples was not conducted before performing sputum culture; however, between 2016 and 2018, quality evaluation of sputum samples was conducted first, and only quality-assured samples were cultured. The numbers of sputum and BALF in 2013-2015 were 15,549 and 1671, while those in 2016-2018 were 12,055 and 3735, respectively. The results of pathogen culture showed that Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Staphylococcus aureus, Hemophilus influenzae, Escherichia coli, Stenotrophomonas maltophilia, and Streptococcus pneumoniae were in the top ten pathogens isolated from sputum and BALF. An antimicrobial susceptibility test showed that the susceptibility of BALF isolates to most antibiotics was higher compared with the susceptibility of sputum isolates, especially after quality control of sputum samples (2016-2018).

CONCLUSIONS

Our findings suggest that caution is needed in making therapeutic choices for patients with LRI when using antimicrobial sensitivity results from sputum isolates as opposed to BALF isolates.

<em>Streptococcus suis</em> meningitis related to processing and consuming raw pork during Balinese tradition, <em>Mebat</em>

Streptococcus suis is a zoonotic pathogen that can infect humans, especially meningitis. S. suis meningitis has been commonly diagnosed in Bali, which is associated with the consumption of raw pork. We reported case of S. suis meningitis that could have occurred due to the ingestion of undercooked pork during a traditional ceremony, which also involved two more patients with similar symptoms. A 62-year-old male was brought to the emergency unit because of decreased consciousness (Glasgow coma scale 14/15) in the last 8 hours before admission. He also had a headache, high fever, and stiff neck. Examination of cerebrospinal fluid revealed the presence of S. suis infection and was confirmed by polymerase chain reaction. The patient was administered ceftriaxone and showed a clinical improvement on the third day without any hearing problem.

Isolation and identification of Streptococcus suis from sick pigs in Bali, Indonesia

Objective

Streptococcus suis (S. suis) is a causative agent for various syndromes in pigs. It can be transmitted to humans with typical symptoms of meningitis and death. Although human infections have been confirmed at Bali Referral Hospital, Indonesia, since 2014, the bacteria have not been isolated from pigs. Here, we provide confirmation of the presence of the bacteria in sick pigs in the province.

Results

Streptococcus suis was confirmed in 8 of 30 cases. The final confirmation was made using PCR and sequencing of the glutamate dehydrogenase (GDH) and recombination/repair protein (recN) gene fragments. Upon PCR serotyping, two were confirmed to be serotype 2 or 1/2. Prominent histopathological lesions of confirmed cases were meningitis, endocarditis, pericarditis, bronchopneumonia, enteritis and glomerulonephritis. The dominant inflammatory cells were neutrophils and macrophages. Further research is needed to understand the risk factors for human infection. Community awareness on the risk of contracting S. suis and vaccine development are needed to prevent human infections.