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PubMed1983

[In vitro activity of josamycin in a comparison of Staphylococcus aureus, Streptococcus pyogenes and Streptococcus pneumoniae].

The antibacterial effect of josamycin has been tested in vitro on strains of S. Aureus, Str. Pyogenes and Str. Pneumoniae isolated during 1981 from human liquor, blood and purulent secretions. It is confirmed that even modest doses of the antibiotic have this effect upon S. Aureus strains which are resistant to several antibiotics including erythromycin and lincomycin. In some cases, although bacteriostasis occurred, bacterial survival indices were fairly modest.

Dose-Response Relationship, Drug↗
PubMed1983

Ultrastructural visualization of the adherence of Streptococcus mutans and Streptococcus salivarius to hydroxyapatite.

S. mutans and S. salivarius adherence to saliva-coated and saliva-uncoated hydroxyapatite was studied by transmission and high resolution scanning electron microscopy. No difference was observed between the saliva-coated and saliva-uncoated study series of adherence. The attachment of individual bacteria to apatite crystals was found to be mediated by cell wall projections. These electron-dense structures were characteristically well formed in S. mutans, and even in S. salivarius the projections appeared to link the bacteria to the apatite. The site of attachment in the bacterial cell wall was always at the division area. We suggest that the possible metabolic activity at the cell wall division site, therefore, also works in the adherence process.

Cell Wall↗
PubMed1980

IgA1 proteases from Haemophilus influenzae, Streptococcus pneumoniae, Neisseria meningitidis, and Streptococcus sanguis: comparative immunochemical studies.

IgA1 proteases from H. influenzae, N. meningitidis, S. pneumoniae, and S. sanguis were compared with respect to site of cleavage in the IgA1 molecule and EDTA sensitivity. Proteases from S. sanguis and S. pneumoniae cleaved the Pro (227)-Thr (228) bond within the hinge region of the alpha 1 chain and were inhibited by EDTA. H. influenzae IgA1 protease cleaved the Pro (231)-Ser (232) peptide bond. The activity of IgA1 proteases from H. influenzae and N. meningitidis was unaffected by EDTA. Purified and denatured alpha 1 chain was cleaved only in the hinge region. Other component chains of secretory IgA (secretory component, light and J chains) were not susceptible. In addition to IgA1 protease, S. pneumoniae released exo- and endoglycosidases that removed a considerable portion of carbohydrate side chains of IgA1; this activity was absent from crude IgA1 protease preparations of the other three bacterial species. Association in vitro of polymeric IgA1 with SC did not inhibit the degradation of IgA1 proteases. The considerable resistance of secretory IgA to cleavage by IgA1 proteases may be explained in part by the presence of IgA1 protease-neutralizing antibodies in secretory IgA.

Amino Acid Sequence↗
PubMed1995

[Prevention of cariogenic dental plaque. Study of the structures implicated in the adhesion and coaggregation in Streptococcus mutans and Streptococcus sobrinus].

Cariogenic dental plaque may be assimilated to a biofilm resulting from the adhesion of S. mutans, then from the coaggregation of other streptococci, or other genus. We used a static monospecific biofilm model. Supports or bacteria were treated with inhibitors before adhesion in order to clarify the nature of adhesins responsible for the primary adhesion of S. mutans and S. sobrinus on Tygon. To determine the bindings of coaggregation, inhibitors were applied on one-day-old biofilms. Analysis of effects were performed by automatic inoculator Spiral (Interscience) for microbiological methods, and by SEM JEOL 5400 LV for microscopic methods. In the aim of preventing adhesion and coaggregation, different traps were assayed:sugars, chemical inhibitors such as F- and EDTA salts. Of these, only the latter showed efficiency. This confirmed the role of bivalent mineral ions and electrostatic attraction forces in the adhesion and coaggregation of streptococci.

Adhesins, Bacterial↗