new_n_lost
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A previously healthy 11-year-old girl develops a gastrointestinal infection with cramping and watery stools. After several days, she begins to pass blood per rectum, and is hospitalized for dehydration. In the hospital, she is noted to have decreasing urine output with rising blood urea nitrogen (BUN). Total blood count reveals anemia and thrombocytopenia, and the peripheral smear is remarkable for fragmented red cells (schistocytes).
Infection with which of the following bacterial genera is most likely responsible for this syndrome?
A. Campylobacter
B. Clostridium
C. Salmonella
D. Shigella
E. Vibrio
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FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
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| unique1
InGodITrust
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D
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I can't change the direction of the wind, but I can adjust my sails to always reach my destination.
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| po
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| bactitech
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I have personally experienced a Shigella flexneri (Group B) infection. It was back in 1982. I was very ill. I started with cramping around 4 a.m. on a Sunday morning. By noon my temperature was at 104 degrees F and I was starting to pass blood. By later in the afternoon I had extreme tenesmus and my stools had turned totally to bloody mucus. I was sick for two weeks and lost 15 lbs. I got it from a culture I had worked on that Saturday at work.
I have seen bloody mucousy stools come down with orders only for Ova and Parasites. At my old employer I would call the doctor and "suggest" that they order a culture. At my current employer we just don't have time to do this.
Why do docs order the least likely test that will produce any results with a patient who obviously is ill when they produce a stool looking like that? Make sure you ask your patients what type of stool they are having and how often. Make sure you take a good history of where they've been and what they've eaten.
On the other extreme, we get rock hard pellets for testing that rattle around in the cup like marbles. What is the purpose of testing these types of stools for C. difficile, culture, or anything besides occult blood???
A good patient history will lead the way to what you need to order. We recently dropped all O&P testing and are substituting Giardia antigen/Cryptosporidium antigen. A full O&P will only be run when a patient has a history of significant travel history or longstanding chronic diarrhea. The doc has to call us back within 72 hours to get a full O&P run. Very very few are done now. We are in the upper northcentral midwest. The only positives we had were Giardia in the last couple of years.
Think about where your patient lives and what they've been exposed to - THEN order your stool testing. You will come up with more meaningful results.
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Clinical Microbiology since 1974
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| new_n_lost
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FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
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| new_n_lost
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The correct answer is D.
This patient has developed hemolytic-uremic syndrome (HUS), a complication of the Shiga toxin or Shiga-like toxin: exotoxins released by Shigella species and the enterohemorrhagic E.coli. HUS in children usually develops after a gastrointestinal or flu-like illness, and is characterized by bleeding, oliguria, hematuria and microangiopathic hemolytic anemia. Presumably the Shiga toxin is toxic to the microvasculature, producing microthrombi that consume platelets and RBCs, and may fragment the red cell membrane.
The incorrect choices are all bacteria which may produce an enterocolitis, but do not elicit HUS.
A long-term consequence of Campylobacter (choice A) infection is a reactive arthritis or full-blown Reiter's syndrome.
Clostridial enterocolitis is produced by Clostridium difficile (choice B), a normal inhabitant of the gut that produces pseudomembranous colitis when other gut flora are suppressed by treatment with antibiotics.
In the United States, Salmonella infections (choice C) are almost all non-typhoid inflammatory diarrhea, producing a simple enterocolitis that may proceed to sepsis in some cases. Typhoid fever (produced by Salmonella typhi and S. paratyphi) produces a protracted illness that progresses over several weeks and includes rash and very high fevers, but not HUS.
Vibrio (choice E) infections produce copious amounts of watery diarrhea, and the major risk of cholera and other Vibrio enteritides is shock due to hypovolemia or electrolyte loss.
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FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
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| lq2006
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Shigella (HUS)
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