ABSTRACT
Streptococcus anginosus and the closely related species Streptococcus constellatus and Streptococcus intermedius, are primarily commensals of the mucosa. The true pathogenic potential of this group has been under-recognized for a long time because of difficulties in correct species identification as well as the commensal nature of these species. In recent years, streptococci of the S. anginosus group have been increasingly found as relevant microbial pathogens in abscesses and blood cultures and they play a pathogenic role in cystic fibrosis. Several international studies have shown a surprisingly high frequency of infections caused by the S. anginosus group. Recent studies and a genome-wide comparative analysis suggested the presence of multiple putative virulence factors that are well-known from other streptococcal species. However, very little is known about the molecular basis of pathogenicity in these bacteria. This review summarizes our current knowledge of pathogenicity factors and their regulation in S. anginosus.
Subject(s)
Streptococcal Infections/microbiology , Streptococcus anginosus , Adhesins, Bacterial/metabolism , Humans , RNA, Ribosomal, 16S , Streptococcus anginosus/genetics , Streptococcus anginosus/pathogenicity , Streptococcus constellatus/genetics , Streptococcus constellatus/metabolism , Streptococcus constellatus/pathogenicity , Streptococcus intermedius/genetics , Streptococcus intermedius/metabolism , Streptococcus intermedius/pathogenicity , Symbiosis/physiology , Virulence , Virulence Factors/metabolismABSTRACT
The aim of the present investigation was to compare the in vitro bacterial retention on saliva-coated implant materials (pure titanium grade 2 (cp-Ti) and a titanium alloy (Ti-6Al-4V) surfaces), presenting similar surface roughness, and to assess the influence of physico-chemical surface properties of bacterial strain and implant materials on in vitro bacterial adherence. Two bacterial strains (one hydrophilic strain and one hydrophobic strain) were used and the following were evaluated: bacterial cell adherence, SFE values as well as the Lifshitz-van-der Waals, the Lewis acid base components of SFE, the interfacial free energy and the non-dispersive interactions according to two complementary contact angle measurement methods: the sessile drop method and the captive bubble method. Our results showed similar patterns of adherent bacterial cells on saliva-coated cp-Ti and saliva-coated Ti-6Al-4V. These findings could suggest that bacterial colonization (i.e. plaque formation) is similar on saliva-coated cp-Ti and Ti-6Al-4V surfaces and indicate that both materials could be suitable for use as transgingival abutment or healing implant components. The same physico-chemical properties exhibited by saliva-coated cp-Ti and TA6V, as shown by the sessile drop method and the captive bubble method, could explain this similar bacterial colonisation. Therefore, higher values of total surface free energy of saliva-coated cp-Ti and saliva-coated TA6V samples (gamma(SV) approximately 65mJ/m(2)) were reported using the captive bubble method indicating a less hydrophobic character of these surfaces than with the sessile drop method (gamma(S) approximately 44.50mJ/m(2)) and consequently possible differences in oral bacterial retention according the theory described by Absolom et al. The number of adherent hydrophobic S. sanguinis cells was two-fold higher than that of hydrophilic S. constellatus cells. Our results confirm that physico-chemical surface properties of oral bacterial strains play a role in bacterial retention to implant materials in the presence of adsorbed salivary proteins.
Subject(s)
Bacterial Adhesion/physiology , Dental Implants/microbiology , Dental Materials/chemistry , Entropy , Saliva/microbiology , Dental Alloys/chemistry , Energy Metabolism , Hydrophobic and Hydrophilic Interactions , Saliva/chemistry , Streptococcus constellatus/metabolism , Streptococcus sanguis/metabolism , Surface Properties , Titanium/chemistryABSTRACT
The aim of this study was to establish an identification method for the anginosus group within the genus Streptococcus by polymerase chain reaction (PCR). Using a primer pair based on the group-specific sequences of penicillin-binding protein 2B (pbp2b) gene, a 275-bp fragment was amplified from each species in the group but no size-matched products were obtained in other streptococci. Further identification in the species or subspecies level was possible by a multiplex PCR with primers for the 16S ribosomal RNA gene of Streptococcus anginosus, the hyaluronate lyase genes both of Streptococcus intermedius and Streptococcus constellatus subsp. constellatus, and the intermedilysin (ily) gene of S. intermedius. In the case ofStreptococcus constellatus subsp. pharyngis, the amplified fragment from the S. intermedius-type hyaluronate lyase gene was obtained, while that from the ily gene was not. These results also indicate that two different hyaluronate lyase genes are distributed among the anginosus group.
