mani
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are they facultative anaerobes or microaerophills? plz give refrencee with ur answer.
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| kalsam
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Streptococci r " Microaerophilic"
Ref: Clinical Micro-MRS, Page No-7, Fig 1-10 Oxygen Spectrum of the major bacterial groups.
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| Sakaki-
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Streptococci are facultative anaerobes. I'm pretty sure that that "microaerophilic" thing is an error; in every other book I have seen, it is stated as a facultative anaerobe (ex. Diagnostic Microbiology by Koneman (5th ed)).
In the lab, strictly microaerophilic bacteria (ie. Campylobacter) must be incubated in a microaerophilic environment to grow. On the other hand, streptococci will grow in normal O2 incubation (35 Celsius) and on the plate incubated under anaerobic conditions.
At the same time, some strains of streptococci do grow better under anaerobic conditions, but that certainly does not make the genus, as a whole, "microaerophilic."
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| kalsam
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Do kaplan say anything about this?? :icon_scratch:
Thx sakaki..I did completely belived that it is microphilic..all ur comments makes sense it has a faculty to be an anaerobe!!
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| mani
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MRS itself has written in tha summery chart of strp that they are facultative anaerobes. thats why i brought it into discussion.
now a imp point is that we all know that strep are catalase -ve. so they should be microaerophillics according to the description of MRS about oxygen comsuption where it says that facultative anaerobes have catalase and superoxidee dismutase while microaerophills have only superoxidee dismutase.
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| mani
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no comments????????????? anybody please!
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| Sakaki-
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I'm sure that that rule is not absolute. For example, Campylobacter jejuni (or any Campylobacter sp.) is microaerophilic, and it is catalase positive.
Lactobacilli lack catalase activity, yet they are not obligately anaerobic (though they do prefer an anaerobic environment). They are not microaerophilic, however, either.
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| bactitech
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I have to chuckle at this discussion. Technically, in a laboratory setting, you are all right. S. pneumo grows better anaerobically sometimes - indeed it will come up in the anaerobic blood culture bottle faster than the anaerobic bottle SOMETIMES (and that is the key here).
Beta streptococci show their beta hemolysis better anaerobically, but will grow aerobically quite well, although some will grow better aerobically better than others.
True anaerobic streptococci, i.e. Peptostreptococcus sp., are true anaerobes. However, most of the other ones grow both ways.
Sometimes we pick up enterococci on the anaerobic plates if the aerobic plates are swarmed over with Proteus. VRE's especially will grow on anaerobic KV agar, as the plate selects out for the Vanco resistant enterococci.
I know you all are studying for boards, but in real life, micro is not this cut and dried :| .
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| bactitech
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Campylobacter needs specialized microphilic atmosphere to grow. We use Campy paks to house the Campy plates. We put them in bags, seal them with a gas generator, and incubate at 42 degrees C for two days before looking at them. In other labs we've used jars hooked up to special gas we buy from a vendor.
Our criteria are oxidase pos, catalase pos, darting motility, and curved gram negative rods. We then issue a preliminary report as "Campylobacter sp." and try to further speciate by plating with Nalidixic acid and Cephalothin Disc. These are not for sensis but for ID only.
If NA resistant and CF sensitive, we call it Campylobacter jejuni/coli.
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| Sakaki-
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We do a smear, oxidase, catalase, and a hippurate. If the hippurate is pos, then we call Campylobacter jejuni. Based on the first three (smear, oxidase, catalase) (off a campy plate of course - Skirrow's is the one we use), we call Campylobacter species.
We stopped doing the nalidixic acid, cephalothin testing a while ago (for what reason, I don't know).
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| Dr. Hussam
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all strep groups are facultative anaerobe except strep pyogenes which is microaerophilic, this is written in microbiology made ridiculously simple
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| alexbuc
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they aremostely facultative anaerobs
except grup a beta hemolitic they are microaerphilis
refernces -mark galdwin clinical microbiology(the chart from streprococci)
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| alexbuc
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they aremostely facultative anaerobs
except grup a beta hemolitic they are microaerphilis
refernces -mark galdwin clinical microbiology(the chart from streprococci)
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hello...i strated to prepare my usmle step1....need to know more about...looking for someone to work with
alex
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