Alpha Hemolytic Streptococci
The pseudo- taxonomic term "Streptococcus viridans" is often used to refer to this group of species, but writers that do not like to use the pseudotaxonomic term which treats a group Streptococcus viridans in der Prostata species as if they were one species prefer the terms viridans streptococci viridans group streptococci VGSStreptococcus viridans in der Prostata viridans streptococcal species. These species possess no Lancefield antigens.
Viridans streptococci can be differentiated from Streptococcus pneumoniae using an optochin test, as viridans streptococci are optochin-resistant; they also lack either the polysaccharide -based capsule typical of S. The organisms are most abundant in the mouth, and one member of the group, S. Others may be involved in other mouth or gingival infections as pericoronitis.
If they are introduced into the bloodstream, they have the potential of causing endocarditisin particular in individuals with damaged heart valves.
They are the most common causes of subacute bacterial endocarditis. Viridans streptococci have the unique ability to synthesize dextrans from glucosewhich allows them to adhere to fibrin - platelet aggregates at damaged heart valves. This mechanism underlies their ability to cause subacute valvular heart disease following their introduction into the bloodstream e. Phenotypic and biochemical identification.
Identification of VGS to the species level can be difficult, and phenotypic identification is not always accurate. Lack of alpha hemolysis does not seem to correlate with the clinical outcome or severity of disease; no enzymatic or toxigenic Streptococcus viridans in der Prostata has ever been documented as a Streptococcus viridans in der Prostata of alpha hemolysis. The VGS are a group of catalase-negative, Gram-positive cocci with a chaining morphology on microscopic examination.
They are leucine aminopeptidase positive, pyrrolidonylarylamidase negative, and do not Streptococcus viridans in der Prostata in 6. They differ from pneumococci in that they are optochin resistant and are not bile soluble. However, Richter et al. The authors also found that optochin disk testing did not perform as well as bile solubility testing for identification; in a survey of 1, isolates tested, bile solubility testing had higher sensitivity and specificity for differentiation of VGS from pneumococci The S.
The isolates lacking beta-hemolysis are generally those grouped with the VGS. There is some evidence implicating beta-hemolytic S. Isolates of the S. Members of the group are universally positive for three biochemical reactions: acetoin production from glucose positive Vogues-Proskauer reactionarginine, and sorbitol.
These are very useful for the differentiation of this group from other VGS. The use of invalid species names Streptococcus viridans in der Prostata also been a particular problem with the S.
Isolates in this group are negative for acetoin production, arginine, esculin, and mannitol and are sorbitol fermentation negative As the organism is closely related to S. Bile solubility is a more specific test for Streptococcus viridans in der Prostata. The genetically heterogeneous S. Some taxonomists have lumped the S. Isolates in the S. Like members of the S. Members of this group are esculin positive and sorbitol negative and produce acetoin.
Historically, S. Isolates from the S. However, S. Although infection with S. Species from this group that have been isolated from human infection include S. Members of the S. They do not hydrolyze arginine but are positive for acetoin production, esculin hydrolysis, and mannitol and sorbitol fermentation.
Automated biochemical methods for identification. For the VGS, the use of automated systems for identification has historically been reported as problematic, and this theme applies to multiple automated methodologies. One of the major factors affecting the quality of the identifications generated is that the systems may not have all species represented in their databases Among the most problematic identifications whether incorrectly identified or unresolved were the VGS; S.
Ninety-one percent of the streptococcal isolates showed agreement between the Phoenix and the reference method. Of the 12 S. Of 22 S. Sequence-based identification. However, these procedures are not practical for clinical laboratories to use for identification of these organisms. Other sequence-based identification systems have subsequently been introduced for VGS species level identification. In light of the high degree of 16S rRNA gene sequence similarity, sequencing of alternative gene targets for reliable identification to the species level has been explored.
One promising target, rnpB, was explored by Innings et al. Streptococcus viridans in der Prostata the Streptococcus viridans in der Prostata species analyzed, all were identified to species level, except for 2 isolates: S. One other successful approach is sequence analysis of the manganese-dependent superoxide dismutase gene, described by Poyart et al.
This technique was used to accurately differentiate over 29 streptococcal species, including 16 VGS species, with clear differentiation of S. Other techniques that have been used, with various degrees of success, are sequence analysis of the 16SS intergenic spacer region, d-alanine-d-alanine ligase gene sequencing, and hyaluronate lyase gene sequencing. May International Journal of Medical Microbiology. Retrieved 31 October Sherris Medical Microbiology 4th ed.
McGraw Hill. In Baron S; et al. Baron's Medical Microbiology 4th ed. Univ Streptococcus viridans in der Prostata Texas Medical Branch. Viridans streptococci : S. Streptococcus iniae Cutaneous Streptococcus iniae infection. Bacillus anthracis Anthrax Bacillus cereus Food poisoning. Listeria monocytogenes Listeriosis. Clostridium difficile Pseudomembranous colitis Clostridium botulinum Botulism Clostridium tetani Tetanus. Clostridium perfringens Gas gangrene Clostridial necrotizing enteritis.
Streptococcus viridans in der Prostata magnus. Ureaplasma urealyticum Ureaplasma infection Mycoplasma genitalium Mycoplasma pneumoniae Mycoplasma pneumonia. Erysipelothrix rhusiopathiae Erysipeloid. Sensitivity to optochin. A : bacitracin susceptible: S. Clostridium spore -forming motile: Clostridium difficile Pseudomembranous colitis Clostridium botulinum Botulism Clostridium tetani Tetanus. Mycoplasmataceae Ureaplasma urealyticum Ureaplasma infection Mycoplasma genitalium Mycoplasma pneumoniae Mycoplasma pneumonia.