Membrane vesicles derived from Streptococcus suis serotype 2 induce cell pyroptosis in endothelial cells via the NLRP3/Caspase-1/GSDMD pathway

Streptococcus suis serotype 2(S.suis 2)is a zoonotic pathogen that clinically causes severe swine and human infections(such as meningitis,endocarditis,and septicemia).In order to cause widespread diseases in different organs,S.suis 2 must colonize the host,break the blood barrier,and cause exaggerated inflammation.In the last few years,most studies have focused on a single virulence factor and its influences on the host.Membrane vesicles(MVs)can be actively secreted into the extracellular environment contributing to bacteria-host interactions.Gram-negative bacteria-derived outer membrane vesicles(OMVs)were recently shown to activate host Caspase-11-mediated non-canonical inflammasome pathway via deliverance of OMV-bound lipopolysaccharide(LPS),causing host cell pyroptosis.However,little is known about the effect of the MVs from S.suis 2(Gram-positive bacteria without LPS)on cell pyroptosis.Thus,we investigated the molecular mechanism by which S.suis 2 MVs participate in endothelial cell pyroptosis.In this study,we used proteomics,electron scanning microscopy,fluorescence microscope,Western blotting,and bioassays,to investigate the MVs secreted by S.suis 2.First,we demonstrated that S.suis 2 secreted MVs with an average diameter of 72.04 nm,and 200 proteins in MVs were identified.Then,we showed that MVs were transported to cells via mainly dynamin-dependent endocytosis.The S.suis 2 MVs activated NLRP3/Caspase-1/GSDMD canonical inflammasome signaling pathway,resulting in cell pyroptosis,but it did not activate the Caspase-4/-5 pathway.More importantly,endothelial cells produce large amounts of reactive oxygen species(ROS)and lost their mitochondrial membrane potential under induction by S.suis 2 MVs.The results in this study suggest for the first time that MVs from S.suis 2 were internalized by endothelial cells via mainly dynamin-dependent endocytosis and might promote NLRP3/Caspase-1/GSDMD pathway by mitochondrial damage,which produced mtDNA and ROS under induction,leading to the pyroptosis of endothelial cells.

Epidemiological observations of invasive group B Streptococcus infections in six major hospitals in Peninsular Malaysia

Objective:To address the lack of research on invasive group B Streptococcus(GBS)infections in Malaysia and Southeast Asia through a comprehensive analysis of GBS isolates obtained from hospitals.Methods:Medical records from patients with GBS infection isolated from the sterile site,such as blood and cerebrospinal fluid from 14 July 2019 to 15 December 2020,were reviewed from six major hospitals in Peninsular Malaysia.Inclusion criteria were invasive GBS,sterile sites and non-repeated GBS isolated from the same patients in the same admission.Viable isolates were re-identified for GBS and serotyped.Results:A total of 118 patients were eligible,with a majority of non-pregnant adults(76.3%).Over half of the patients(62.7%)had underlying medical conditions,with diabetes as the most common disease,followed by respiratory disease,renal disease,cardiovascular disease and skin and soft tissue disease.The most common manifestations were sepsis,followed by soft tissue abscess,diabetic foot ulcer,wet gangrene and cellulitis.The overall mortality was 7.6%.The most common serotype was serotype桋.Conclusions:Invasive GBS infection among non-pregnant adults showed a rising trend,particularly among diabetic individuals.The study underscores the importance of reducing risk factors and highlights the necessity of developing GBS vaccination as a preventive strategy for both infants and adults.

Strain-specific effect of Streptococcus thermophilus consumption on host physiology

Streptococcus thermophilus is one of the most prevalent species in stool samples of westernized populations due to continuous exposure to fermented dairy products.However,few studies have explored the effect on host physiology by multiple S.thermophilus strains and considered the inter-strain differences in regulating host.In the present study,we investigated how four S.thermophilus strains influenced the gut microbiota,mucin changes,and host metabolism after 28 days of intervention in conventional mice.The results indicated that the consumption of S.thermophilus affected the host with strain specificity.Among four S.thermophilus strains,DYNDL13-4 and DQHXNQ38M61,especially DQHXNQ38M61,had more effect on host physiology by modulating gut microbiota and host metabolism than LMD9 and 4M6.Ingestion of strains DYNDL13-4 and DQHXNQ38M61 resulted in more remarkable changes in amino acid metabolism and lipid metabolism than that of strains LMD9 and 4M6,which may be related to the elevation of intestinal Bifidobacterium by DYNDL13-4 and DQHXNQ38M61.The enriched Coriobacteriaceae UCG-002,Rikenellaceae RC9 gut group,and Lactobacillus only in the DQHXNQ38M61 group,had a close relationship with the prominent effect of DQHXNQ38M61 on regulating amino acid and lipid metabolism.In addition,DQHXNQ38M61 had a strong influence on degrading colonic mucin fucose by decreasedα-fucosidase activity in feces,and improving mucin sulfation by upregulated Gal3ST2 expression.Comparative genomic analysis revealed that the four S.thermophilus strains belonged to different branches in the phylogenetic tree,and DYNDL13-4 and DQHXNQ38M61 had more genes involved in carbohydrate metabolism,amino acid metabolism,membrane transport,and signal transduction,which may confer the capacity of nutrient utilization and gastrointestinal adaptation of the strains and be associated with their strong regulation in host.Our study provides valuable information for understanding the regulation of host metabolism after consuming different S.thermophilus strains and could facilitate potential personalized applications of S.thermophilus based on strain varieties.

Protective eff ect and mechanism of nanoantimicrobial peptide ND-C14 against Streptococcus pneumoniae infection

BACKGROUND:Streptococcus pneumoniae(S.pneumoniae)is a common pathogen that causes bacterial pneumonia.However,with increasing bacterial resistance,there is an urgent need to develop new drugs to treat S.pneumoniae infections.Nanodefensin with a 14-carbon saturated fatty acid(ND-C14)is a novel nanoantimicrobial peptide designed by modifying myristic acid at the C-terminus of humanα-defensin 5(HD5)via an amide bond.However,it is unclear whether ND-C14 is effective against lung infections caused by S.pneumoniae.METHODS:In vitro,three groups were established,including the control group,and the HD5 and ND-C14 treatment groups.A virtual colony-count assay was used to evaluate the antibacterial activity of HD5 and ND-C14 against S.pneumoniae.The morphological changes of S.pneumoniae treated with HD5 or ND-C14 were observed by scanning electron microscopy.In vivo,mice were divided into sham,vehicle,and ND-C14 treatment groups.Mice in the sham group were treated with 25μL of phosphate-buffered saline(PBS).Mice in the vehicle and ND-C14 treatment groups were treated with intratracheal instillation of 25μL of bacterial suspension with 2×108 CFU/mL(total bacterial count:5×10^(6) CFU),and then the mice were given 25μL PBS or intratracheally injected with 25μL of ND-C14(including 20μg or 50μg),respectively.Survival rates were evaluated in the vehicle and ND-C14 treatment groups.Bacterial burden in the blood and bronchoalveolar lavage fluid were counted.The lung histology of the mice was assessed.A propidium iodide uptake assay was used to clarify the destructive eff ect of ND-C14 against S.pneumoniae.RESULTS:Compared with HD5,ND-C14 had a better bactericidal eff ect against S.pneumoniae because of its stronger ability to destroy the membrane structure of S.pneumoniae in vitro.In vivo,ND-C14 significantly delayed the death time and improved the survival rate of mice infected with S.pneumoniae.ND-C14 reduced bacterial burden and lung tissue injury.Moreover,ND-C14 had a membrane permeation eff ect on S.pneumoniae,and its destructive ability increased with increasing ND-C14 concentration.CONCLUSION:The ND-C14 may improve bactericidal eff ects on S.pneumoniae both in vitro and in vivo.

Streptococcus anginosus in the development and treatment of precancerous lesions of gastric cancer

The microbiota is strongly association with cancer.Studies have shown significant differences in the gastric microbiota between patients with gastric cancer(GC)patients and noncancer patients,suggesting that the microbiota may play a role in the development of GC.Although Helicobacter pylori(H.pylori)infection is widely recognized as a primary risk factor for GC,recent studies based on microbiota sequencing technology have revealed that non-H.pylori microbes also have a significant impact on GC.A recent study discovered that Streptococcus anginosus(S.anginosus)is more prevalent in the gastric mucosa of patients with GC than in that of those without GC.S.anginosus infection can spontaneously induce chronic gastritis,mural cell atrophy,mucoid chemotaxis,and heterotrophic hyperplasia,which promote the development of precancerous lesions of GC(PLGC).S.anginosus also disrupts the gastric barrier function,promotes the proliferation of GC cells,and inhibits apoptosis.However,S.anginosus is underrepresented in the literature.Recent reports suggest that it may cause precancerous lesions,indicating its emerging pathogenicity.Modern novel molecular diagnostic techniques,such as polymerase chain reaction,genetic testing,and Ultrasensitive Chromosomal Aneuploidy Detection,can be used to gastric precancerous lesions via microbial markers.Therefore,we present a concise summary of the relationship between S.anginosus and PLGC.Our aim was to further investigate new methods of preventing and treating PLGC by exploring the pathogenicity of S.anginosus on PLGC.

Infantile bacterial meningitis combined with sepsis caused by Streptococcus gallolyticus subspecies pasteurianus:A case report

BACKGROUND Streptococcus gallolyticus subspecies pasteurianus(SGSP)is a rare pathogen responsible for infant sepsis and meningitis and is potentially overlooked because it is not included in routine group B streptococcal screenings.Hence,we present a case of SGSP-induced infant meningitis and sepsis,accompanied by bronchopneumonia induced by multidrug-resistant Staphylococcus aureus(MRSA),providing insights into the identification,management,and prognosis of this bacterial infection.CASE SUMMARY A 45-day-old female infant presented with two episodes of high fever(maximum temperature:39.5°C)and two generalized grand mal seizure episodes that lasted over ten seconds and self-resolved without concomitant symptoms.Postadmission,the patient’s C-reactive protein level was 40.73 mg/L,white blood cell count was 13.42×10^(9)/L,neutrophil ratio was 78.4%,procalcitonin level was 7.89μg/L,cerebrospinal fluid(CSF)white cell count was 36×10^(6)/L,multinucleated cell ratio was 95.2%,and protein concentration was 0.41 g/L.Blood and CSF culture revealed that the pathogen was SGSP.The bacterium was sensitive to ampicillin,furazolidone,penicillin,lincomycin,moxifloxacin,rifampicin,vancomycin,and levofloxacin but resistant to clindamycin and tetracycline.Sputum culture revealed the presence of MRSA,which was sensitive to vancomycin.The patient was diagnosed with meningitis and sepsis caused by SGSP,accompanied by bronchopneumonia induced by MRSA.Ceftriaxone(100 mg/kg/d)combined with vancomycin(10 mg/kg/dose,q6h)was given as an anti-infective treatment postadmission.After 12 days of treatment,the infant was discharged from the hospital with normal CSF,blood culture,and routine blood test results,and no complications,such as subdural effusion,were observed on cranial computed tomography.No growth retardation or neurological sequelae occurred during follow-up.CONCLUSION SGPSP-induced infant bacterial meningitis and sepsis should be treated with prompt blood and CSF cultures,and a sensitive antibiotic therapy to ensure a favorable prognosis.

Brain abscess caused by Streptococcus anginosus group:Three case reports

BACKGROUND This case series investigated the clinical manifestations,diagnoses,and treatment of cerebral abscesses caused by Streptococcus anginosus.We retrospectively analyzed the clinical characteristics and outcomes of three cases of cerebral abscesses caused by Streptococcus anginosus and conducted a comprehensive review of relevant literature.CASE SUMMARY Case 1 presented with a history of left otitis media and exhibited high fever,confusion,and vomiting as primary symptoms.Postoperative pus culture indicated a brain abscess caused by Streptococcus constellatus infection.Case 2 experienced dizziness for two days as the primary symptom.Postoperative pus culture suggested an intermediate streptococcal brain abscess.Case 3:Enhanced head magnetic resonance imaging(MRI)and diffusion-weighted imaging revealed occupancy of the left temporal lobe,initially suspected to be a metastatic tumor.However,a postoperative pus culture confirmed the presence of a brain abscess caused by Streptococcus anginosus infection.The three cases presented in this case series were all patients with community-acquired brain abscesses resulting from angina caused by Streptococcus group infection.All three patients demonstrated sensitivity to penicillin,ceftriaxone,vancomycin,linezolid,chloramphenicol,and levofloxacin.Successful treatment was achieved through stereotaxic puncture,drainage,and ceftriaxone administration with a six-week course of antibiotics.CONCLUSION Preoperative enhanced head MRI plays a critical role in distinguishing brain tumors from abscesses.Selecting the correct early diagnostic methods for brain abscesses and providing timely intervention are very important.This case series was in accordance with the CARE guidelines.

Acute coalescent mastoiditis in a 16-month-old child due to Streptococcus pneumoniae infection

Rationale:Acute otitis media is a common disease in early childhood,and is usually caused by Streptococcus pneumoniae(S.pneumoniae).Acute mastoiditis is a complication of acute otitis media and can involve not only the mucoperiosteum of the middle ear but can also spread to the periosteum by destroying the mastoid bone(acute coalescent mastoiditis).In addition,the infection can extend through the surrounding bones or the emissary veins beyond the mastoid’s air cells,leading to subperiosteal abscesses.Patient’s Concern:A 16-month-old female patient was hospitalized due to the purulent discharge of the left ear and the symptoms of right mastoiditis(swelling and redness of the skin).Diagnosis:Bilateral acute coalescent mastoiditis caused by S.pneumoniae infection.The computer tomography revealed bilateral bone destruction of the mastoid and abscesses found behind the auricle on both sides.Interventions:The patient underwent intravenous antibiotic therapy and surgical treatment.Outcomes:The patient was discharged 14 days after hospitalization with an improved condition.Lessons:Improperly treated acute coalescent mastoiditis can lead to extracranial and intracranial complications,sometimes serious and even life-threatening.Complications are prevalent in children under 2 years,in whom the disease progresses more rapidly and severely.The vaccination with a 13-valent vaccine may not result in sufficient immunity against S.pneumoniae,a predominant pathogen in children affected by acute coalescent mastoiditis.

Pulmonary abscess caused by Streptococcus pseudopneumoniae in a child:A case report and review of literature

BACKGROUND Lung abscess found on chest X-ray and computed tomography examinations is rare in infants and young children.Several pathogens can cause lung abscesses,with the most common pathogens being anaerobes,Streptococci and Staphylococcus aureus.Streptococcus pseudopneumoniae(S.pseudopneumoniae)is a member of the Streptococcaceae family,and is mainly isolated from respiratory tract specimens.There are currently no cases of lung abscess caused by S.pseudopneumoniae in the literature.CASE SUMMARY A 2-year-old boy was admitted to hospital due to persistent cough and fever.Lung computed tomography examination suggested the formation of a lung abscess.His diagnosis was not confirmed by testing for serum respiratory pathogens(6 items),respiratory pathogen nucleic acid(27 items),and laboratory culture.Finally,metagenomic next-generation sequencing of bronchoalveolar lavage fluid revealed the presence of S.pseudopneumoniae,confirming its role in causing the lung abscess.After receiving antibiotic treatment,reexamination with lung computed tomography showed that the abscess was resorbed and the patient’s outcome was good.CONCLUSION This is the first report of a lung abscess in a child caused by S.pseudopneumoniae infection.Metagenomic next-generation sequencing of bronchoalveolar lavage fluid is helpful in achieving rapid and accurate pathogen identification.

Antimicrobial and synergistic effects of lemongrass and geranium essential oils against Streptococcus mutans,Staphylococcus aureus,and Candida spp.

BACKGROUND The oral cavity harbors more than 700 species of bacteria,which play crucial roles in the development of various oral diseases including caries,endodontic infection,periodontal infection,and diverse oral diseases.AIM To investigate the antimicrobial action of Cymbopogon Schoenanthus and Pelargonium graveolens essential oils against Streptococcus mutans,Staphylococcus aureus,Candida albicans,Ca.dubliniensis,and Ca.krusei.METHODS Minimum microbicidal concentration was determined following Clinical and Laboratory Standards Institute documents.The synergistic antimicrobial activity was evaluated using the Broth microdilution checkerboard method,and the antibiofilm activity was evaluated with the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay.Data were analyzed by one-way analysis of variance followed by the Tukey post-hoc test(P≤0.05).RESULTS C.schoenanthus and P.graveolens essential oils were as effective as 0.12%chlorhexidine against S.mutans and St.aureus monotypic biofilms after 24 h.After 24 h P.graveolens essential oil at 0.25%was more effective than the nystatin group,and C.schoenanthus essential oil at 0.25%was as effective as the nystatin group.CONCLUSION C.schoenanthus and P.graveolens essential oils are effective against S.mutans,St.aureus,Ca.albicans,Ca.dubliniensis,and Ca.krusei at different concentrations after 5 min and 24 h.

Antibiotic Resistance Profile of Serotypes of Streptococcus pneumoniae Strains in Bangui, from 2017 to 2022: Case of Serotype 1

Goals: The aim of this study was to determine the antibiotic resistance profile of serotypes of Streptococcus pneumoniae strains circulating in Bangui. Methodology: A prospective and analytical analysis was carried out at the National Laboratory of Clinical Biology and Public Health from 2017 to 2022. The strains came from our study on the contribution to the study of antibiotic sensitivity of Streptococcus pneumoniae strains. The multiplex PCR test was used for its cost-effectiveness in terms of amplifiers which can be purified in order to be sequenced. It also makes it possible to detect several germs as well as their serotypes. For a PCR reaction, several elements are involved in the reaction medium or Master Mix. These are the desoxyribonucleotides (dNTPs), the magnesium ions (MgCl2) and the primers. A set of 14 primers divided into 3 classes were used. Class 1 primers served as an internal control by targeting the cpsA gene. It is a highly conserved gene found in capsular loci characterized to date. The primers of the second class were used to target specific serotypes by specific reactions (out of six possibilities). The group reaction was carried out using the primers of the third class in order to carry out an initial screening of the samples and to classify the pneumococcal isolates. Related serotypes were grouped based on the amplification of common genes. Using the technique of electrophoresis on agarose gel and an ultraviolet radiation device, the migration bands are then visualized and analyzed. The data collected had been entered into Excel 2010 and analyzed with Epi info 7. The exact Fischer chi2 test at the 5% threshold, the relative risk and its 95% confidence interval were used to compare the proportions and determine the associations. Results: 187 antibiotic-resistant strains of Streptococcus pneumoniae were collected. The average frequency of serotypes 1, 9A, 4 and untypeable identified were 43.59%, 18.18%, 18.27% and 39.57% respectively. The frequency of serotype 1 was predominant for the age group over five years old with 56.88%. The male sex was predominant with 55.08% for serotype 1. Resistance to penicillin and gentamicin for serotype 1 during this study, for the age group under 5 years old, was 77%. For serotypes 19A and 4, tetracycline resistance was predominant with 20% for the age group under 5 years. The resistance to penicillin and gentamicin of non-typeable serotypes was 33% for the age group under 5 years old. For the age group over 5 years old, resistance to erythromycin predominated at 37%. The distribution of serotypes by sex depending on antibiotic resistance was variable. There was a statistically significant association between identified serotypes and antibiotic resistance (p Conclusion: The study determined serotypes 1, serotypes 19A, serotypes 4 and non-typeable serotypes. These results would be due to the quality of vaccination or poor protection of vaccines.

Methylome and transcriptome data integration reveals potential roles of DNA methylation and candidate biomarkers of cow Streptococcus uberis subclinical mastitis

Background:Mastitis caused by different pathogens including Streptococcus uberis(S.uberis)is responsible for huge economic losses to the dairy industry.In order to investigate the potential genetic and epigenetic regulatory mecha‑nisms of subclinical mastitis due to S.uberis,the DNA methylome(whole genome DNA methylation sequencing)and transcriptome(RNA sequencing)of milk somatic cells from cows with naturally occurring S.uberis subclinical mastitis and healthy control cows(n=3/group)were studied.Results:Globally,the DNA methylation levels of CpG sites were low in the promoters and first exons but high in inner exons and introns.The DNA methylation levels at the promoter,first exon and first intron regions were nega‑tively correlated with the expression level of genes at a whole‑genome‑wide scale.In general,DNA methylation level was lower in S.uberis‑positive group(SUG)than in the control group(CTG).A total of 174,342 differentially methylated cytosines(DMCs)(FDR<0.05)were identified between SUG and CTG,including 132,237,7412 and 34,693 DMCs in the context of CpG,CHG and CHH(H=A or T or C),respectively.Besides,101,612 methylation haplotype blocks(MHBs)were identified,including 451 MHBs that were significantly different(dMHB)between the two groups.A total of 2130 differentially expressed(DE)genes(1378 with up‑regulated and 752 with down‑regulated expression)were found in SUG.Integration of methylome and transcriptome data with MethGET program revealed 1623 genes with signifi‑cant changes in their methylation levels and/or gene expression changes(MetGDE genes,MethGET P‑value<0.001).Functional enrichment of genes harboring≥15 DMCs,DE genes and MetGDE genes suggest significant involvement of DNA methylation changes in the regulation of the host immune response to S.uberis infection,especially cytokine activities.Furthermore,discriminant correlation analysis with DIABLO method identified 26 candidate biomarkers,including 6 DE genes,15 CpG‑DMCs and 5 dMHBs that discriminated between SUG and CTG.Conclusion:The integration of methylome and transcriptome of milk somatic cells suggests the possible involve‑ment of DNA methylation changes in the regulation of the host immune response to subclinical mastitis due to S.uberis.The presented genetic and epigenetic biomarkers could contribute to the design of management strategies of subclinical mastitis and breeding for mastitis resistance.

Molecular epidemiology, characterization of virulence factors and antibiotic resistance profile of Streptococcus agalactiae isolated from dairy farms in China and Pakistan

Streptococcus agalactiae is one of the most common pathogens that cause bovine mastitis worldwide. Identifying pathogen prevalence and virulence factors is critical for developing prevention and control approaches. Herein, 1 161 milk samples from various dairy farms in China(n=558) and Pakistan(n=603) were collected between 2019–2021 and were subjected to S. agalactiae isolation. Prevalence, serotyping, virulence genes, and antibiotic-resistant genes of S. agalactiae were evaluated by PCR assay. All isolates were characterized for haemolysis, biofilm production, cytotoxicity, adhesion, and invasion on bovine mammary epithelial cells. The prevalence of S. agalactiae-induced mastitis in cattle was found to be considerably higher in Pakistan than in China. Jiangsu and Sindh provinces had the highest area-wise prevalence in China and Pakistan, respectively. Serotypes Ia and II were prevalent in both countries, whereas serotype III was found only in Pakistan. Moreover, all isolates tested positive for PI-2b gene but negative for PI-1 and PI-2a genes. All isolates harboured cfb, cylE, hylB, and fbsB virulent genes, whereas many of them lacked bibA, rib and bca. However, the absence of bac and scp genes in Chinese isolates and cspA in Pakistani isolates was noted, while spb1 and lmb were not detected in isolates of both countries. Pakistani isolates, particularly serotype Iapositive, had a considerably higher ability to produce biofilm, haemolysis, cytotoxicity, adhesion, and invasion than Chinese isolates. Most of the isolates were phenotypically resistant to tetracycline, erythromycin, and clindamycin and genotypic resistance was confirmed by the presence of ermA, ermB, tetM and tetO genes. Our study highlights the antimicrobial resistance profile and virulence-related factors contributing to the epidemiological spread of mastitis-causing S. agalactiae in China and Pakistan. The findings may facilitate future studies designed to develop improved treatment and control strategies against this pathogen.

The vital role of CovS in the establishment of Streptococcus equi subsp.zooepidemicus virulence

Streptococcus equi subsp.zooepidemicus(SEZ)is an important zoonotic agent.Here,a virulence-attenuated strain M35246 derived from natural variation of wild-type SEZ ATCC35246 was found.M35246 showed a deletion of 25contiguous genes as well as a loss-of-function mutation in covS.Subsequently,a 25-gene-deleted strain(ΔPI),a covS-mutant strain(Mcov S),and relevant complementary strains were constructed and investigated.M35246 and Mcov S were significantly less encapsulated and exhibited poorer anti-phagocytic capacity compared to wild-type SEZ.McovS was significantly more sensitive toβ-lactams,aminoglycosides,macrolides,and lincosamides than wild-type SEZ.M35246,McovS,andΔPI exhibited an increase in median lethal dose(LD_(50))in mice by 10~5,10~5,and 5 times when compared to wild-type SEZ,respectively.Neither M35246 nor McovS were isolated from mice 48 h after being challenged with approximately 2000 times the LD_(50)of wild-type SEZ.Transcriptome analysis showed that 668 significantly differentially expressed genes existed between McovS and wild-type SEZ.Numerous virulence factor-encoding genes and anabolicrelated genes in McovS that were involved in anti-phagocytosis,capsule formation,pathogenicity,and antibiotic resistance were downregulated significantly relative to the wild-type strain.This study revealed that the CovS plays a vital role in the establishment of SEZ virulence.

Dihydroartemisinin ameliorates innate inflammatory response induced by Streptococcus suis-derived muramidase-released protein via inactivation of TLR4-dependent NF-kB signaling

Muramidase-released protein(MRP)is now being recognized as a critical indicator of the virulence and pathogenicity of Streptococcus suis(S.suis).However,the identification of viable therapeutics for S.suis infection was hindered by the absence of an explicit mechanism for MRP-actuated inflammation.Dihydroartemisinin(DhA)is an artemisinin derivative with potential anti-inflammatory activity.The modulatory effect of DhA on the inflammatory response mediated by the virulence factor MRP remains obscure.This research aimed to identify the signaling mechanism by which MRP triggers the innate immune response in mouse spleen and cultured macrophages.With the candidate mechanism in mind,we investigated DhA for its ability to dampen the pro-inflammatory response induced by MRP.The innate immune response in mice was drastically triggered by MRP,manifesting as splenic and systemic inflammation with splenomegaly,immune cell infiltration,and an elevation in pro-inflammatory cytokines.A crucial role for Toll-like receptor 4(TLR4)in coordinating the MRP-mediated inflammatory response via nuclear factor-kappa B(NF-kB)activation was revealed by TLR4 blockade.In addition,NFkB-dependent transducer and activator of transcription 3(STAT3)and mitogen-activated protein kinases(MAPKs)activation was required for the inflammatory signal transduction engendered by MRP.Intriguingly,we observed an alleviation effect of DhA on the MRP-induced immune response,which referred to the suppression of TLR4-mediated actuation of NF-kB-STAT3/MAPK cascades.The inflammatory response elicited by MRP is relevant to TLR4-dependent NF-kB activation,followed by an increase in the activity of STAT3 or MAPKs.DhA mitigates the inflammation process induced by MRP via blocking the TLR4 cascade,highlighting the therapeutic potential of DhA in targeting S.suis infection diseases.

Disease burden,antimicrobial resistance and molecular characterization of invasive group B Streptococcus among non-pregnant adults in Malaysia:A protocol study

and pili genes are also investigated.Methods:This multicentre,prospective,observational study is conducted in seven major tertiary hospitals in Malaysia among non-pregnant adults.Simultaneously,a retrospective study is conducted in the selected hospitals with similar approaches.GBS isolates are subjected to phenotyping,serotyping by multiplex PCR,antimicrobial susceptibility testing and PCR-detection of GBS virulence and pilus genes.Seven housekeeping genes are amplified and sequenced for multi-locus sequence typing.Discussion:Findings from the study may contribute to the management of clinical practice to diagnose and prevent GBS related diseases in a timely manner.Prudent use of antibiotics is encouraged by monitoring antimicrobial resistance.

Valve repair after infective endocarditis secondary to perforation caused by Streptococcus gordonii:A case report

BACKGROUND We report a case of infective endocarditis(IE)in a patient with congenital heart valve lesions accompanied by IE,which was diagnosed based on blood culture analysis that revealed the presence of a gram-negative bacterium,Streptococcus gordonii.CASE SUMMARY The patient had a history of precordial valve disease diagnosed by cardiac ultrasound,as well as a 4-mo history of fever.He was subjected to comprehensive anti-infection and anti-heart failure treatment in the internal medicine department.Further examination revealed sudden dislodgement from and perforation through the aortic valve by the superfluous organisms,as well as occurrence of bacterial emboli dislodgement,which caused bacteremia and infectious shock.He recovered and was discharged from the hospital after surgical and postoperative anti-infection treatments.CONCLUSION We review the treatment process and highlight inspirations and reflections from this case;suggest possible future changes in treatment modalities.

The Antibacterial Activities of Copper Oxide Nanoparticles Synthesized Using Laser Ablation in Different Surfactants against Streptococcus mutans

Copper oxide nanoparticles(CuO NPs)were synthesised with laser ablation of a copper sheet immersed in deionized water(DW),cetrimonium bromide(CTAB),and sodium dodecyl sulphate(SDS),respectively.The target was irradiated with a pulsed Nd:YAG laser at 1064 nm,600 mJ,a pulse duration of 10 ns,and a repetition rate of 5 Hz.The CuO NPs colloidal were analyzed using UV–Vis spectroscopy,the Fourier transform infrared(FTIR)spectrometer,zeta potential(ZP),X-ray diffraction(XRD),transmission electron microscope(TEM)and field emission scanning electron microscopy(FESEM).The absorption spectra of CuO NPs colloidal showed peaks at 214,215 and 220 nm and low-intensity peaks at 645,650 and 680 nm for SDS,CTAB and DW,respectively.CuO NPs’colloidal results are(−21.6,1.2,and 80 mV)for negatively,neutrally,and positively charged SDS,DW,and CTAB,respectively.The XRD pattern of the NPs revealed the presence of CuO phase planes(110)(111),(20-2)and(11-1).The TEM images revealed nearly spherical NPs,with sizes ranging from 10–90,10–50,and 10–210 nm for CuO NPs mixed with DW,SDS and CTAB,respectively.FESEM images of all the synthesized samples illustrate the formation of spherical nanostructure and large particles are observable.The CuO NPs were tested for antibacterial activity against Streptococcus mutans by using the well diffusion method.In this method,CuO NPs prepared in DW at a concentration of 200μg/mL showed a greater inhibition zone against Streptococcus mutans.

ST of Streptococcus pneumonia Circulating in Burkina Faso before the Introduction of PCV-13, 2013

Introduction: Burkina Faso experiences regular cases of Streptococcus pneumoniae meningitis. As part of the strategy to reduce cases of meningitis, the 13-valent pneumococcal conjugate vaccine (PCV-13) has been introduced in the Expanded Programme on Immunisation (EPI). Despite these efforts, there are some cases of pneumococcal meningitis including both vaccine and non-vaccine serotypes. The objective of this study was to describe the pneumococcal sequence types (ST) circulating in Burkina Faso before the introduction of the 13-valent pneumococcal conjugate vaccine (PCV-13). Methods: It was a descriptive cross-sectional study that took place from 27th October 2013 to 7th January 2014. S. pneumoniae strains were collected in Burkina Faso and Multi Locus Sequence Typing (MLST) was performed at the Pneumococcal Laboratory at the Centers for Disease Control and Prevention (CDC) in the USA (United States of America). MLST consists of 4 steps: amplification, purification, sequencing and interpretative reading of the results. The amplification used 7 primers consisting of sequences of aroe, gdh, gki, recP, spi, xpt, ddl genes. Results: Of 37 strains tested, 10 serotypes were identified. Serotype 1 was prevalent in 48.7% (18/37) followed by serotype 25F in 10.8% (4/37). Serotypes 5 and 12F/12A/12B/44/46 were 8.1% (3/37) each. Serotype 1 contained 5 STs including ST303 24.3% (9/37), ST217 8.1% (3/37) and ST618 8.1% (3/37);followed by serotype 25F with ST105 10.8% (4/37), serotype 5 with ST289 8.1% (3/37) and serogroup 12F/12A/12B/44/46 with ST 989 8.1% (3/37). Conclusion: Pneumococci are characterised by their great variability both in number of serotypes and in ST within the same serotype. Thus, 10 serotypes have been identified. Also, within serotype 1, 5 different STs have been described. These data indicate the complexity of the pneumococcus which is strongly involved in purulent bacterial meningitis at national level. This requires continuous surveillance of pneumococcal meningitis through laboratory capacity building.

Streptococcus pneumoniae and Herpes Simplex Virus-1 Central Nervous System Co-Infection

Co-infections of the central nervous system (CNS) caused by bacterial and viral pathogens are considered to be rare. Herpes simplex virus type-1 (HSV-1) reactivation following Streptococcus pneumoniae infection is well described but most cases are related to oral or cutaneous lesions or in respiratory samples. HSV-1 CNS reactivation after Streptococcus pneumoniae meningitis is a very rare event and may have significant morbidity and mortality. In this case report, we describe a 71-year-old female patient that presented with a history of abdominal pain and confusion/disorientation that had tonic-clonic seizures while in the Emergency Department. The diagnostic work-up confirmed CNS co-infection caused by Streptococcus pneumoniae and HSV-1. Of note, beyond age, the patient had no known risk factors for both entities and recovered fully after antibiotic and antiviral therapy. This case underlines that clinicians must be aware of CNS co-infection despite being a rare diagnosis. This should be suspected particularly in patients who present an unusual clinical course of CNS infection.