Is Strep mitis a member of the Strep Viridans species

[SweetSarah]

this is an alpha-hemolytic strep species. I want to make sure if s. mitis is part of that or if same thing?
the way my book words it kind of confuses me and sounds like they're the same. they seem to be interchanged sometimes too. I know this is a really simple question but I cant find anything online about this.

I probably have this as my unknwons and can't find much online about this organism. almost everything would instead be about the other organisms like Strep pneumoniae so that's kinda annoying for me since I need to write lots of info about it. If anyone else knows any good websites particullarly with information about Strep mitis, that would be helpful. thanks in advance.

[JorgeLobo]

"Steptocococus viridans" (viridans group) is a nontaxonomic grouping of commensal, alpha or gamma hemolytic strep that do not possess Lancefield antigens. Streptoccoccus mitis possesses these characteristics and can be considered within this group.

[JorgeLobo]

btw - strep pneumo is optochin senstive and the viridans are all resistant. there are a few real old tests - bile solubility and "Quellung" reaction.

[SweetSarah]

btw - strep pneumo is optochin senstive and the viridans are all resistant. there are a few real old tests - bile solubility and "Quellung" reaction.

hey thanks for clearing that up for me Jorge and for helping me out again! Your help is really appreciated

I actually did those tests before as you mentioned except the "quellung" reaction (since it wasn't really necessary and we didn't go over this in class) but I know that Strep pneumo is positive for all the tests while S. mitis is negative. So if I do have S. mitis in my paper, would it ever be okay to interchange it as "S. viridans" sometimes since "S. mitis is a member of S. Viridans...if I am understanding correctly. thanks though

[JorgeLobo]

S. viridans is not a species. Are you sure it's mitis? In any case, I'd with the correct taxonomy - S. mitis.

[xenopus]

S. viridans is not a species. All spreptococci irrespective of haemolysis type have been currently divided into seven genetically distinct groups: pyogenic streptococci (S. pyogenes, S.agalactiae, S. dysgalactiae) - group I; Str. bovis group (II); Str. mitis group (S. mitis, S. pneumoniae, S. oralis, S. sanguis) - group III; S. mutans group (S. mutans, S. sobrinus) - IV; S. salivarius group (V); S. milleri group (S. anginosus, S. intermedius, S. constelatus) - VI; non-affiliated streptococci (VII). Former "viridans group" term nowadays covers S. mitis, S. mutans, S. salivarius and S. milleri group except for S. pneumoniae, which is not considered a viridans Streptococcus despite the genetical affinity.

[SweetSarah]

S. viridans is not a species. All spreptococci irrespective of haemolysis type have been currently divided into seven genetically distinct groups: pyogenic streptococci (S. pyogenes, S.agalactiae, S. dysgalactiae) - group I; Str. bovis group (II); Str. mitis group (S. mitis, S. pneumoniae, S. oralis, S. sanguis) - group III; S. mutans group (S. mutans, S. sobrinus) - IV; S. salivarius group (V); S. milleri group (S. anginosus, S. intermedius, S. constelatus) - VI; non-affiliated streptococci (VII). Former "viridans group" term nowadays covers S. mitis, S. mutans, S. salivarius and S. milleri group except for S. pneumoniae, which is not considered a viridans Streptococcus despite the genetical affinity.

ok this is what i was looking for. thanks for listing all the groups. makes more sense now..

[SweetSarah]

S. viridans is not a species. Are you sure it's mitis? In any case, I'd with the correct taxonomy - S. mitis.

thanks for all your help Jorge. To be honest, I'm not really sure whether it is mitis or pneumoniae but am thinking to go with mitis since the inulin test stayed red so it is negative and so was the bile solubility was also negative. But that last test confused me since it kind of looks clear, so I'm not sure whether it's cloudy or clear but I did the inulin test and it came out negative. I really hope I didn't do anything wrong. This gram positive unknown is due Thurs.

But I know I'm on the right track though, since I asked the TA for some help and she told me if I was. So it ends up I was way wrong before with thinking I had micrococcus...If you know any other better ways I can be sure whether it's pneumo or mitis would be helpful, but it's okay if not since this is due soon and you already helped a lot. I've done the bile solubility and inulin tests so far, all seemed negative but am unsure about the bile one so plan to maybe redo it tomm. what u think?