PatriciaLim
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A 50 year old pt in the hospital with known valvular disease has blood cultures that are positive on the 5th day of incubation of a gram negative coccobacillus. The organism grew very poorly after subculturing(48 hr incubation) as a hazy growth on chocolate and sheep blood agary, but no growth on MacConkey. Oxidase is positive and catalase is positive. The colonies are non beta hemolytic on sheep blood agar and were ONPG negative. The patient most likely has endocarditis due to
A kingella kingae
B eikenella corrodens
C cardiobacterium homminis
D actinobacillus actinomycetemcomitans
E hemophillus aphrophilus
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| disha
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?is it c(just guessing)
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| keepgoing
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? C
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| bactitech
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Boy, without my books at work I have no clue. These organisms occur so rarely I just don't know what the reactions are. I do know that E. corrodens is oxidase positive and doesn't grow on Mac. However, I don't think it is a coccobacillus in morphology. Key to this one is know which of them are oxidase positive and go from there. I'll have to get back to this one.
http://www.emedicine.com/med/topic935.htm This page has some good information on most of the bugs listed, but doesn't go into the reactions. These organisms are the HACEK organisms - you should probably order increased incubation times on your patients if you suspect them. Most of the newer blood culture systems will grow them up in 5 days, but just to be safe, you should probably tell the lab you suspect them. Most blood culture machines have the ability to override the standard five day protocol quite easily, but you must let the lab know.
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| PatriciaLim
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Answer is B correct
The explanation is as below
E corrodens is a slender gram negative bacillus or coccobacilli with rounded ends. The organism is oxidase potive and catalase negative. Growth is on chocholate and sheep blood agar, but not on macConkey agar. Colonies are small, non beta hemolytic, and many times will ''pit'' or ''corrode'' the agar surface. The organism will produce a yellow pigment and a ''chlorox bleach'' odor. E corrodens does not produce acid for carbohydrates. The organism is part of the normal flora or the mouth and upper respiratory tract. E corredends is most commonly associated with dental and periodontal infections, head and neck infections, otitis medic, respiratory infections, and mastoiditis. Patients with recent dental work that are immunocompromised, hav previous valvular damage, or are intravenous drug abusers can develop bacteremia and/or endocarditis due to E corredens. This is a memeber of a fastidious group of organisms sometimes grouped together and called the HACEK group. When suspected the lab should be notified for special specimen consideration.
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| bactitech
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I still disagree with the morphology described for E. corrodens. It is not a coccobacillus.
http://medinfo.ufl.edu/year2/mmid/bms5300/bugs/ei... - it is described here as pleomorphic, which only means that the rods are of different size.
http://web.umr.edu/~microbio/BIO221_1999/E_corrod... - it is described here as small and straight, which to me doesn't include "coccobacilli."
I don't mean to be picky, but the shape and appearance of organisms on a microscope slide is very important. Gram negative coccobacilli to me include H. influenzae and Bacteroides sp., not E. corrodens.
E. corrodens has a very distinctive colony morphology and smell. It usually doesn't show on the plate until the second day, and then is very small. Once you're used to what they look like you can pick them out in a mixed culture and isolate them. By the third day they are very distinctive.
http://www.emedicine.com/MED/topic1033.htm - they show up in human bite infections quite frequently.
[end of micro mini-rant....:-)]
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| keepgoing
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patriciaLim what is ur source of ans...???
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| young_doc
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There are 2 BIG clues in this question:
-chocolate agar
-coccobacilli
I think it could just as likely be Haemophilus. (Which can also cause endocarditis)
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd...
We're not given a proper HPI. For example if our patient had recent dental work done? Or if he had his tongue pierced recently (http://www.cdc.gov/ncidod/EID/vol8no8/01-0458.htm) hahah
This question's debatable..
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