Palaniappan
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4 year old boy with self-limited diarrhoea ,have gram negative non-lactose fermenting ,non-H2s Producing rod..They do not produce gas on fermentation of glucose..
The above mentioned bacterium is
Shigella or Yerisinia enerocolitica???
Help please...The answer given is shigella...Is there any chance of yerisinia in this question??
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| bactitech
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Shigella is nonmotile. Yersinia I believe has variable motility depending on the temperature it's grown in. Scroll down on this page for a full chart of reactions:
http://www.cfsan.fda.gov/~ebam/bam-8.html
Yersinia is motile at room temp and nonmotile at 37 degrees. At 30 degrees you can get a "test tube brush" motility in SIM agar. Urea also appears to be positive for Yersinia. Yersinia grows better at room temp than incubator temperatures, although our laboratory doesn't seem to have any problem finding these growing as small colonies on MacConkey at 2 days.
Shigella must be serotyped with typing serum to prove that it is indeed Shigella. Our lab groups it to A.B.C.D and that's all.
The reactions you have named aren't enough to differentiate these two bugs. Are there more???
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Clinical Microbiology since 1974
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| Palaniappan
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Thanks a lot bactitech ..the question stem says only the above information-Not much
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| babydoc4usmle
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given that's a child, there are more chances for Shigella than Yesinia, but to say definitely that it's either of these bugs more info needed.
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| bactitech
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We have seen Yersinia in about 3-4 children's stool cultures over the last year, so you can't use that as criteria either.
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Clinical Microbiology since 1974
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| babydoc4usmle
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what about Shigella, did you see children with Shigella?
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| Ancylostoma
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I agree with baby doc, trash this question. Its garbage and needs to give us more information. I have read that yersina is possible one of the major causes or diarheal outbreaks, Yersina entercolitica I think and it was in a the answer stem of one of my usmle world question.
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| Palaniappan
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Yes..It is a USMLE World question and these are thie informations given..Nothing more....The answer was given as Shigella ..Anyway..Let's omit it...
Can shigella cause self-limited diarrhoea without dysentery????
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| Ancylostoma
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I guess they said it can. like I said we cant know everything
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| bactitech
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I think that depends on the type of Shigella. I personally experienced Shigella flexneri, and it was WAY more than diarrhea. I was sick for two weeks, lost 15 lbs. and passed nothing but blood and mucus the entire time. I could only eat soda crackers and Ramen noodles. Everything else (and even that stuff sometimes) brought on severe tenesmus. I got it from a specimen at work.
I've known other techs to get Shigella sonnei. Their course of diarrhea ran about 3-4 days. They were sick, though - don't know how you define "self-limited." Another tech had S. flexneri and she was also sick for two weeks.
I agree that this is a poorly worded question with not enough information.
Don't know about gas production on TSI medium between Shigella and Yersinia. I have a feeling that this is the key to this question. Unfortunately, labs using TSI's to screen enteric pathogens are getting to be in the minority. I haven't used the TSI/LIA methodology since about 1980. We just pop suspected colony types in a GNI+ Vitek card. We can have the ID in anywhere from 3-8 hours. This is MUCH faster than the old methodology.
I've said this before: Kaplan hasn't been in a modern micro lab in quite awhile. Their authors really do need to get out more.
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Clinical Microbiology since 1974
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