Viridans streptococci in infective endocarditis: species distribution and susceptibility to antibiotics

Horaud, T; Delbos, F

doi:10.1093/eurheartj/5.suppl_c.39

Cited by 36 publications

(23 citation statements)

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“…Streptococcus mutans is a primary pathogen of human dental caries in the oral cavity and occasionally causes infective endocarditis in patients with heart valve abnormalities (13,17). The cell wall-associated proteins in this microorganism play an important role in bacterial adherence for colonization in distinct host compartments.…”

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A 60-Kilodalton Immunodominant Glycoprotein Is Essential for Cell Wall Integrity and the Maintenance of Cell Shape in Streptococcus mutans

Chia

Chang

Shun³

et al. 2001

Infect Immun

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We have demonstrated previously by Western blotting that in naturally sensitized humans, the serum or salivary antibody response to Streptococcus mutans was directed predominantly to a protein antigen with a size of approximately 60-kDa. To identify this immunodominant antigen, specific serum antibodies were eluted from immunoblots and five positive clones with inserts ranging in length from 3 to 8 kb from identical chromosomal loci were obtained by screening a genomic expression library of Streptococcus mutans GS-5. Amino acid sequencing established the identity of this immunodominant antigen, a 60-kDa immunodominant glycoprotein (IDG-60), to be a cell wall-associated general stress protein GSP-781, which was originally predicted to have a molecular mass of approximately 45 kDa based on the derived nucleotide sequence. Discrepancy in the molecular mass was also observed in recombinant his-tagged IDG-60 (rIDG-60) expressed from Escherichia coli. Glycosylation, consisting of sialic acid, mannose galactose, and N-acetylgalactosamine, was detected by lectin binding to IDG-60 in cell wall extracts from S. mutans and rIDG-60 expressed in vivo or translated in vitro. Despite the presence of multiple Asn or Ser or Thr glycosylation sites, IDG-60 was resistant to the effect of N-glycosidase F and multiple O-glycosidase molecules but not to ␤-galactosidase. Insertional inactivation of the gene encoding IDG-60, sagA, resulted in a retarded growth rate, destabilization of the cell wall, and pleiomorphic cell shape with multifold ingrowth of cell wall. In addition, distinct from the parental GS-5 strain, the isogenic mutant GS-51 was unable to survive the challenge of low pH and high osmotic pressure or high temperature. Expression of the wild-type gene in trans within GS-51 from plasmid pDL277 complemented the growth defect and restored normal cell shape. These results suggested that IDG-60 is essential for maintaining the integrity of the cell wall and the uniformity of cell shape, both of which are indispensable for bacteria survival under stress conditions.

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confidence: 99%

A 60-Kilodalton Immunodominant Glycoprotein Is Essential for Cell Wall Integrity and the Maintenance of Cell Shape in Streptococcus mutans

Chia

Chang

Shun³

et al. 2001

Infect Immun

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“…Streptococcus gallolyticus and Streptococcus lutetiensis in the bovis group are reported to have a strong association with colon cancer (31)(32)(33). Streptococcus anginosus and Streptococcus intermedius in the anginosus group are associated with abscess formation (9,26), and Streptococcus mitis and other normal oral commensals have a strong association with infective endocarditis (6,10,22). The precise species-level identification of NHS from relevant clinical specimens is crucial to making the right diagnosis and understanding the pathogenesis of the infection.…”

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Identification of Clinically Relevant Nonhemolytic Streptococci on the Basis of Sequence Analysis of 16S-23S Intergenic Spacer Region and Partial gdh Gene

et al. 2009

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Nonhemolytic streptococci (NHS) cause serious infections, such as endocarditis and septicemia. Many conventional phenotypic methods are insufficient for the identification of bacteria in this group to the species level. Genetic analysis has revealed that single-gene analysis is insufficient for the identification of all species in this group of bacteria. The aim of the present study was to establish a method based on sequence analysis of the 16S-23S intergenic spacer (ITS) region and the partial gdh gene to identify clinical relevant NHS to the species level. Sequence analysis of the ITS region was performed with 57 NHS reference or clinical strains. Satisfactory identification to the species level was achieved for 14/19 NHS species included in this study on the basis of sequence analysis of the ITS region. Streptococcus salivarius and Streptococcus vestibularis obtained the expected taxon as the best taxon match, but there was a short maximum score distance to the next best match (distance, <10). Streptococcus mitis, Streptococcus oralis, and Streptococcus pneumoniae could not be unambiguously discriminated by sequence analysis of the ITS region, as was also proven by phylogenetic analysis. These five species could be identified to the group level only by ITS sequence analysis. Partial gdh sequence analysis was applied to the 11 S. oralis strains, the 11 S. mitis strains, and the 17 S. pneumoniae strains. All except one strain achieved a satisfactory identification to the species level. A phylogenetic algorithm based on the analysis of partial gdh gene sequences revealed three distinct clusters. We suggest that sequence analysis of the combination of the ITS region and the partial gdh gene can be used in the reference laboratory for the species-level identification of NHS.Streptococci are a heterogeneous group of bacteria consisting of more than 50 species. In addition to the traditional pathogenic pneumococci and hemolytic streptococci (HS), many species of non-HS (NHS), which are part of the commensal microbiota in the human body, are known to be opportunistic pathogens that cause serious systemic and local infections. These infections include subacute infective endocarditis (24), bacteremia in immunocompromised patients (19, 44), brain abscesses (34), meningitis (35), and pneumonia (5).There are reports describing associations between some specific species and clinical manifestations. Streptococcus gallolyticus and Streptococcus lutetiensis in the bovis group are reported to have a strong association with colon cancer (31-33). Streptococcus anginosus and Streptococcus intermedius in the anginosus group are associated with abscess formation (9, 26), and Streptococcus mitis and other normal oral commensals have a strong association with infective endocarditis (6, 10, 22). The precise species-level identification of NHS from relevant clinical specimens is crucial to making the right diagnosis and understanding the pathogenesis of the infection.The conventional phenotypic tests do not always allow accurate ident...

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“…The ability to form biofilms is one of the important virulence properties of S. mutans. This bacterium is also a causative agent of infective endocarditis (8). It is primarily associated with subacute (chronic) infective endocarditis, which involves the colonization of heart tissue having preexisting endothelial damage (22).…”

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Identification and Characterization of an Autolysin-Encoding Gene of Streptococcus mutans

et al. 2005

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We identified a gene (atlA) encoding autolytic activity from Streptococcus mutans Xc. The AtlA protein predicted to be encoded by atlA is composed of 979 amino acids with a molecular weight of 107,279 and has a conserved ␤-1,4-N-acetylmuramidase (lysozyme) domain in the C-terminal portion. Sodium dodecyl sulfate extracts of strain Xc showed two major bacteriolytic bands with molecular masses of 107 and 79 kDa, both of which were absent from a mutant with inactivated atlA. Western blot analysis revealed that the 79-kDa band was derived from the 107-kDa peptide by cleavage of its N-terminal portion. The inactivation of atlA resulted in a marked decrease in autolysis and the formation of very long chains of cells compared to the case for the parent strain. Although both the parent and mutant strains formed biofilms in the presence of sucrose, the biofilms formed by the mutant had a sponge-like architecture with large gaps and contained 30% less biomass than those formed by the parent strain. Furthermore, strain Xc formed glucose-dependent, loose biofilms in the absence of sucrose, but the mutant lost this ability. These results suggest that AtlA may play an important role in biofilm formation by S. mutans. The antibody produced against the C-terminal peptide containing the ␤-1,4-N-acetylmuramidase domain drastically inhibited the autolytic activity of strain Xc. This inhibition was specific among the oral streptococci to S. mutans. These results indicate that the catalytic domain of AtlA is located at the C terminus, suggesting that further characterization of this domain may provide a means to control cariogenic dental plaque formation.

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Viridans streptococci in infective endocarditis: species distribution and susceptibility to antibiotics

Cited by 36 publications

References 0 publications

A 60-Kilodalton Immunodominant Glycoprotein Is Essential for Cell Wall Integrity and the Maintenance of Cell Shape in Streptococcus mutans

A 60-Kilodalton Immunodominant Glycoprotein Is Essential for Cell Wall Integrity and the Maintenance of Cell Shape in Streptococcus mutans

Identification of Clinically Relevant Nonhemolytic Streptococci on the Basis of Sequence Analysis of 16S-23S Intergenic Spacer Region and Partial gdh Gene

Identification and Characterization of an Autolysin-Encoding Gene of Streptococcus mutans

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