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MSphere Dec 2022The viridans group streptococci (VGS) are a large consortium of commensal streptococci that colonize the human body. Many species within this group are opportunistic...
The viridans group streptococci (VGS) are a large consortium of commensal streptococci that colonize the human body. Many species within this group are opportunistic pathogens causing bacteremia and infective endocarditis (IE), yet little is known about why some strains cause invasive disease. Identification of virulence determinants is complicated by the difficulty of distinguishing between the closely related species of this group. Here, we analyzed genomic data from VGS that were isolated from blood cultures in patients with invasive infections and oral swabs of healthy volunteers and then determined the best-performing methods for species identification. Using whole-genome sequence data, we characterized the population structure of a diverse sample of Streptococcus oralis isolates and found evidence of frequent recombination. We used multiple genome-wide association study tools to identify candidate determinants of invasiveness. These tools gave consistent results, leading to the discovery of a single synonymous single nucleotide polymorphism (SNP) that was significantly associated with invasiveness. This SNP was within a previously undescribed gene that was conserved across the majority of VGS species. Using the growth in the presence of human serum and a simulated infective endocarditis vegetation model, we were unable to identify a phenotype for the enriched allele in laboratory assays, suggesting a phenotype may be specific to natural infection. These data highlighted the power of analyzing natural populations for gaining insight into pathogenicity, particularly for organisms with complex population structures like the VGS. The viridians group streptococci (VGS) are a large collection of closely related commensal streptococci, with many being opportunistic pathogens causing invasive diseases, such as bacteremia and infective endocarditis. Little is known about virulence determinants in these species, and there is a distinct lack of genomic information available for the VGS. In this study, we collected VGS isolates from invasive infections and healthy volunteers and performed whole-genome sequencing for a suite of downstream analyses. We focused on a diverse sample of Streptococcus oralis genomes and identified high rates of recombination in the population as well as a single genome variant highly enriched in invasive isolates. The variant lies within a previously uncharacterized gene, , which shared homology with the anaerobic ribonucleoside triphosphate reductase, , and was highly conserved among VGS. This work increased our knowledge of VGS genomics and indicated that differences in virulence potential among S. oralis isolates were, at least in part, genetically determined.
Topics: Humans; Streptococcus oralis; Genome-Wide Association Study; Streptococcus; Viridans Streptococci; Endocarditis; Genomics; Bacteremia; Virulence Factors
PubMed: 36321824
DOI: 10.1128/msphere.00509-22 -
Microbiology Spectrum Aug 2023Radiation caries is one of the most common complications of head and neck radiotherapy. A shift in the oral microbiota is the main factor of radiation caries. A new form...
Radiation caries is one of the most common complications of head and neck radiotherapy. A shift in the oral microbiota is the main factor of radiation caries. A new form of biosafe radiation, heavy ion radiation, is increasingly being applied in clinical treatment due to its superior depth-dose distribution and biological effects. However, how heavy ion radiation directly impacts the oral microbiota and the progress of radiation caries are unknown. Here, unstimulated saliva samples from both healthy and caries volunteers and caries-related bacteria were directly exposed to therapeutic doses of heavy ion radiation to determine the effects of radiation on oral microbiota composition and bacterial cariogenicity. Heavy ion radiation significantly decreased the richness and diversity of oral microbiota from both healthy and caries volunteers, and a higher percentage of Streptococcus was detected in radiation groups. In addition, heavy ion radiation significantly enhanced the cariogenicity of saliva-derived biofilms, including the ratios of the genus Streptococcus and biofilm formation. In the Streptococcus mutans-Streptococcus sanguinis dual-species biofilms, heavy ion radiation increased the ratio of S. mutans. Next, S. mutans was directly exposed to heavy ions, and the radiation significantly upregulated the and cariogenic virulence genes to enhance the biofilm formation and exopolysaccharides synthesis of S. mutans. Our study demonstrated, for the first time, that direct exposure to heavy ion radiation can disrupt the oral microbial diversity and balance of dual-species biofilms by increasing the virulence of S. mutans, increasing its cariogenicity, indicating a potential correlation between heavy ions and radiation caries. The oral microbiome is crucial to understanding the pathogenesis of radiation caries. Although heavy ion radiation has been used to treat head and neck cancers in some proton therapy centers, its correlation with dental caries, especially its direct effects on the oral microbiome and cariogenic pathogens, has not been reported previously. Here, we showed that the heavy ion radiation directly shifted the oral microbiota from a balanced state to a caries-associated state by increasing the cariogenic virulence of S. mutans. Our study highlighted the direct effect of heavy ion radiation on oral microbiota and the cariogenicity of oral microbes for the first time.
Topics: Humans; Streptococcus mutans; Heavy Ions; Dental Caries; Streptococcus; Streptococcus sanguis; Microbiota; Biofilms
PubMed: 37310225
DOI: 10.1128/spectrum.01322-23 -
The ISME Journal May 2020The oral microbiome engages in a diverse array of highly sophisticated ecological interactions that are crucial for maintaining symbiosis with the host. Streptococci and...
The oral microbiome engages in a diverse array of highly sophisticated ecological interactions that are crucial for maintaining symbiosis with the host. Streptococci and corynebacteria are among the most abundant oral commensals and their interactions are critical for normal biofilm development. In this study, we discovered that Streptococcus sanguinis specifically responds to the presence of Corynebacterium durum by dramatically altering its chain morphology and improving its overall fitness. By employing gas chromatography-mass spectrometry (GC-MS) analysis, specific fatty acids were identified in C. durum supernatants that are responsible for the observed effect. Membrane vesicles (MVs) containing these fatty acids were isolated from C. durum supernatants and were able to replicate the chain morphology phenotype in S. sanguinis, suggesting MV as a mediator of interspecies interactions. Furthermore, S. sanguinis responds to C. durum lipids by decreasing the expression of key FASII genes involved in fatty acid synthesis. Several of these genes are also essential for the chain elongation phenotype, which implicates a regulatory connection between lipid metabolism and chain elongation. In addition, C. durum was found to affect the growth, cell aggregation, and phagocytosis of S. sanguinis, revealing a complex association of these species that likely supports oral commensal colonization and survival.
Topics: Biofilms; Corynebacterium; Microbiota; Streptococcus; Streptococcus sanguis; Symbiosis
PubMed: 32020052
DOI: 10.1038/s41396-020-0598-2 -
Antimicrobial Agents and Chemotherapy Nov 2003The activity of garenoxacin, a new quinolone, was determined in comparison with other quinolones against different strains of S. pneumoniae, viridans group streptococci... (Comparative Study)
Comparative Study
In vitro activities of garenoxacin (BMS-284756) against Streptococcus pneumoniae, viridans group streptococci, and Enterococcus faecalis compared to those of six other quinolones.
The activity of garenoxacin, a new quinolone, was determined in comparison with other quinolones against different strains of S. pneumoniae, viridans group streptococci (VGS), and Enterococcus faecalis. Strains were quinolone-susceptible clinical isolates and quinolone-resistant strains with defined mechanisms of resistance obtained from either clinical isolates or derivatives of S. pneumoniae R6. Clinical quinolone-susceptible strains of S. pneumoniae, VGS and E. faecalis showed garenoxacin MICs within a range of 0.03 microg/ml to 0.25 micro g/ml. Garenoxacin MICs increased two- to eightfold when one mutation was present in the ParC quinolone resistance-determining region (QRDR), fourfold when one mutation was present in the GyrA QRDR (S. pneumoniae), 8- to 64-fold when two or three mutations were associated in ParC and GyrA QRDR, and 2,048-fold when two mutations were present in both the GyrA and ParC QRDRs (Streptococcus pneumoniae). Increased active efflux had a moderate effect on garenoxacin MICs for S. pneumoniae and VGS. Against S. pneumoniae, garenoxacin behaved like moxifloxacin and sparfloxacin, being more affected by a single gyrA mutation than by a single parC mutation. Although garenoxacin was generally two- to fourfold more active than moxifloxacin against the different wild-type or mutant strains of S. pneumoniae, VGS, and E. faecalis, it was two- to fourfold less active than gemifloxacin. At four times the respective MIC for each strain, the bactericidal effect of garenoxacin, observed at 6 h for S. pneumoniae and at 24 h for S. oralis and E. faecalis, was not influenced by the presence of mutation either in the ParC or in both the ParC and GyrA QRDRs.
Topics: Anti-Bacterial Agents; Colony Count, Microbial; Drug Resistance, Bacterial; Enterococcus faecalis; Fluoroquinolones; Genes, Bacterial; Microbial Sensitivity Tests; Quinolones; Streptococcus oralis; Streptococcus pneumoniae; Viridans Streptococci
PubMed: 14576115
DOI: 10.1128/AAC.47.11.3542-3547.2003 -
Circulation Jul 2012The American Heart Association published updated guidelines for infective endocarditis (IE) prevention in 2007 that markedly restricted the use of antibiotic prophylaxis...
Incidence of infective endocarditis caused by viridans group streptococci before and after publication of the 2007 American Heart Association's endocarditis prevention guidelines.
BACKGROUND
The American Heart Association published updated guidelines for infective endocarditis (IE) prevention in 2007 that markedly restricted the use of antibiotic prophylaxis in certain at-risk patients undergoing dental and other invasive procedures. The incidence of IE caused by viridans group streptococci (VGS) in the United States after publication of the 2007 American Heart Association guidelines has not been reported.
METHODS AND RESULTS
We performed a population-based review of all definite or possible cases of VGS-IE using the Rochester Epidemiology Project of Olmsted County, Minnesota. Patient demographics and microbiological data were collected for all VGS-IE cases diagnosed from January 1, 1999, through December 31, 2010. We also examined the Nationwide Inpatient Sample hospital discharge database to determine the number of VGS-IE cases included between 1999 and 2009. We identified 22 cases with VGS-IE in Olmsted County over the 12-year study period. Rates of incidence (per 100 000 person-years) during time intervals of 1999-2002, 2003-2006, and 2007-2010 were 3.19 (95% confidence interval, 1.20-5.17), 2.48 (95% confidence interval, 0.85-4.10), and 0.77 (95% confidence interval, 0.00-1.64), respectively (P=0.061 from Poisson regression). The number of hospital discharges with a VGS-IE diagnosis in the Nationwide Inpatient Sample database during 1999-2002, 2003-2006, and 2007-2009 ranged between 15 318 to 15 938, 16 214 to 17 433, and 14 728 to 15 479, respectively.
CONCLUSIONS
On the basis of data complete through 2010, there has been no perceivable increase in the incidence of VGS-IE in Olmsted County, Minnesota, since the publication of the 2007 American Heart Association endocarditis prevention guidelines.
Topics: American Heart Association; Endocarditis; Endocarditis, Bacterial; Female; Humans; Incidence; Male; Population Surveillance; Practice Guidelines as Topic; Streptococcal Infections; United States; Viridans Streptococci
PubMed: 22689929
DOI: 10.1161/CIRCULATIONAHA.112.095281 -
BMC Nephrology Oct 2018The clinical course of Viridans streptococci (VS) peritonitis in patients undergoing peritoneal dialysis (PD) is rarely reported. This study examined the association of... (Comparative Study)
Comparative Study
BACKGROUND
The clinical course of Viridans streptococci (VS) peritonitis in patients undergoing peritoneal dialysis (PD) is rarely reported. This study examined the association of clinical factors with VS peritonitis.
METHODS
We retrospectively reviewed clinical data from patients with VS peritonitis from March 1990 to February 2016 in a PD center in Taiwan and evaluated clinical profiles and treatment outcomes.
RESULTS
A total of 109 episodes of VS peritonitis in 71 patients identified. Among these patients, 57 had mono-VS peritonitis and 14 had concurrent polymicrobial infections. The median time interval from PD initiation to the first VS peritonitis episode was 18 months (range, 0.6-144 months). Among clinical outcomes, most VS peritonitis episodes were completely cured regardless of a history of peritonitis. All episodes with catheter removal occurred in those without a history of recent antibiotic use.
CONCLUSION
VS peritonitis in patients undergoing PD typically has favorable treatment outcomes. Antibiotic therapy should be started promptly.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Anti-Bacterial Agents; Cohort Studies; Coinfection; Female; Gram-Negative Bacterial Infections; Gram-Positive Bacterial Infections; Humans; Male; Middle Aged; Peritoneal Dialysis; Peritonitis; Retrospective Studies; Streptococcal Infections; Taiwan; Viridans Streptococci; Young Adult
PubMed: 30340562
DOI: 10.1186/s12882-018-1078-z -
The Journal of Clinical Pediatric... Sep 2020The aim of this study was to evaluate synergy and inhibitory effects of xylitol and erythritol on Streptococcus mutans and Streptococcus sobrinus growth and biomass...
The aim of this study was to evaluate synergy and inhibitory effects of xylitol and erythritol on Streptococcus mutans and Streptococcus sobrinus growth and biomass production on a polystyrene plastic surface. Study design; S. mutans and sobrinus strains (American Type Culture Collection reference strains 31341, 35668, 25175, sobrinus 33478) were cultivated in media (Todd Hewitt Broth with 1% sucrose or heart-brain infusion broth with 1% sucrose) at differing concentrations of xylitol or erythritol in microtiter assay plates incubated for 48 hours. Bacterial growth was quantified and measured by optical density using a microplate reader. Experiments assessing synergy and biofilm growth were carried out also using microdilution assays. All four strains were inhibited by 30% (w/v) xylitol, and 15% erythritol at 150mg/ml erythritol, 2/4 strains had reduced growth; at 270mg/ml, 4/4 strains were inhibited. Bactericidal effects were not observed at any polyol concentration. Combinations of both polyols in a checker board array were used to determine if there were any benefits of polyol combinations. Results The combination studies yielded mixed outcomes with indifference in growth for strains 68 and 78, potential additive effect for strain 75 and possible antagonism for strain 41. Assessment of biomass formation and polyol interference were also performed post MIC assessment. Strains 41, 68 and 75 produced significant biomass in the absence of either polyol. Both polyols inhibited biomass formation in a dose-dependent fashion. Strain 75 is a poor biomass producer and could not be assessed for polyol effects in our assay. Conclusion: Our results demonstrate significant polyol influence on the oral Streptococcal strains tested in our laboratory.
Topics: Biofilms; Erythritol; Humans; Streptococcus mutans; Streptococcus sobrinus; Xylitol
PubMed: 33181842
DOI: 10.17796/1053-4625-44.5.4 -
Microbiological Research Jan 2011Due to the major role of Streptococcus mutans and Streptococcus sobrinus in the etiology of dental caries, it is important to use culture media that allow for...
Due to the major role of Streptococcus mutans and Streptococcus sobrinus in the etiology of dental caries, it is important to use culture media that allow for differentiating these bacterial species. The aim of this study was to evaluate the suitability of a modified SB-20 culture medium (SB-20M) for the isolation and morphological differentiation of S. mutans and S. sobrinus, compared to biochemical identification (biotyping). Saliva samples were collected using the spatula method from 145 children, seeded on plates containing the SB-20M, in which sucrose was replaced by coarse granular cane sugar, and incubated in microaerophilia at 37°C during 72 h. Identification of the microorganisms was performed under stereomicroscopy based on colony morphology of 4904 colonies. The morphological identification was examined by biochemical tests of 94 randomly selected colonies with the macroscopic characteristic of S. mutans and S. sobrinus using sugar fermentation, resistance to bacitracin and production of hydrogen peroxide. There was no statistically significant difference (p>0.05) between morphological identification in the SB-20M medium and biochemical identification (biotyping). Biotyping confirmed that S. mutans and S. sobrinus colonies were correctly characterized in the SB-20M in 95.8% and 95.5% of the cases, respectively. Of the mutans streptococci detected in the children 98% were S. mutans and 2% S. sobrinus. The SB-20M medium is reliable for detection and direct morphological identification of S. mutans and S. sobrinus.
Topics: Bacterial Typing Techniques; Child; Culture Media; Dental Caries; Humans; Saliva; Streptococcus mutans; Streptococcus sobrinus
PubMed: 20092983
DOI: 10.1016/j.micres.2010.01.001 -
PloS One 2015Viridans Group Streptococci (VGS) species-level identification is fundamental for patients management. Matrix-assisted laser desorption ionization-time of flight mass... (Comparative Study)
Comparative Study
Viridans Group Streptococci (VGS) species-level identification is fundamental for patients management. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been used for VGS identification but discrimination within the Mitis group resulted difficult. In this study, VGS identifications with two MALDI-TOF instruments, the Biotyper (Bruker) and the VITEK MS (bioMérieux) have been compared to those derived from tuf, soda and rpoB genes sequencing. VGS isolates were clustered and a dendrogram constructed using the Biotyper 3.0 software (Bruker). RpoB gene sequencing resulted the most sensitive and specific molecular method for S. pneumonia identification and was used as reference method. The sensitivity and the specificity of the VITEK MS in S. pneumonia identification were 100%, while the Biotyper resulted less specific (92.4%). In non pneumococcal VGS strains, the group-level correlation between rpoB and the Biotyper was 100%, while the species-level correlation was 61% after database upgrading (than 37% before upgrading). The group-level correlation between rpoB and the VITEK MS was 100%, while the species-level correlation was 36% and increases at 69% if isolates identified as S. mitis/S. oralis are included. The less accurate performance of the VITEK MS in VGS identification within the Mitis group was due to the inability to discriminate between S. mitis and S. oralis. Conversely, the Biotyper, after the release of the upgraded database, was able to discriminate between the two species. In the dendrogram, VGS strains from the same group were grouped into the same cluster and had a good correspondence with the gene-based clustering reported by other authors, thus confirming the validity of the upgraded version of the database. Data from this study demonstrated that MALDI-TOF technique can represent a rapid and cost saving method for VGS identification even within the Mitis group but improvements of spectra database are still recommended.
Topics: Bacterial Typing Techniques; Genotyping Techniques; Sensitivity and Specificity; Software; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Viridans Streptococci
PubMed: 25781023
DOI: 10.1371/journal.pone.0120502 -
Medicine Jul 2020In the course of endocarditis, the development of antineutrophil cytoplasmic antibody (ANCA)-mediated disease introduces the dilemma of determining the best treatment... (Review)
Review
RATIONALE
In the course of endocarditis, the development of antineutrophil cytoplasmic antibody (ANCA)-mediated disease introduces the dilemma of determining the best treatment approach for immune conditions, whether immunosuppressant therapy should be added to antibiotic treatment has remained controversial.
PATIENT CONCERNS
A 33-year-old man presented with progressive fever lasting for 7 months, and swelling, pain, and purpura in the arms and legs. The patient showed multiple autoantibodies including cytoplasmic ANCA, antiproteinase 3, rheumatoid factor, and anti-beta 2 glycoprotein I. Blood culture was positive for viridans streptococcus, and renal biopsy revealed glomerulonephritis and interstitial nephritis.
DIAGNOSIS
Endocarditis caused by viridans streptococci, ANCA-associated vasculitis, and congenital ventricular septal defect.
INTERVENTIONS
In addition to effective antibiotics, he also received twice intravenous corticosteroids and intravenous immunoglobulin therapy, and a low dose of cyclophosphamide. At last, the patient received congenital ventricular septal defect repair and debridement.
OUTCOMES
The abnormal clinical manifestations, including renal failure and loss of strength, recovered rapidly with corticosteroid therapy in addition to antibiotic treatment. After 6 months without any medications, he remained asymptomatic and was able to live normally.
LESSONS
In this case with endocarditis and ANCA-associated vasculitis, we highlighted the importance of biopsy and immunosuppressive therapy. Histopathologic examination is required for diagnosis and treatment in such case. Identifying patients who have endocarditis and ANCA positivity with vasculitis pathologic features will require corticosteroid/immunosuppressives in addition to the antibiotics therapy.
Topics: Adrenal Cortex Hormones; Adult; Anti-Bacterial Agents; Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis; Diagnosis, Differential; Endocarditis, Bacterial; Humans; Immunoglobulins, Intravenous; Immunotherapy; Male; Streptococcal Infections; Viridans Streptococci
PubMed: 32702934
DOI: 10.1097/MD.0000000000021358