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  #1  
Old 06-24-2014
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Wink best next step in diagnosing lyme

A 33-year-old man comes to the clinic with a
rapidly expanding target-shaped rash on his
shoulder in the same spot where he removed a
tick 3 days ago. The physician suspects Lyme
disease. Which of the following is the next step
in diagnosis?
(A) Biopsy rash and culture for Borrelia burg-
dorferi
(B) Collect plasma and culture for Borrelia
burgdorferi
(C) Collect plasma and test for Lyme antigen
(D) Collect plasma for enzyme-linked immu-
nosorbent assay and Western blot analysis
(E) Collect urine and test for Lyme antigen
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  #2  
Old 06-26-2014
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Default answer

which is the correct answer in your opinion?
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  #3  
Old 06-26-2014
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Default

Quote:
Originally Posted by giovanni83 View Post
A 33-year-old man comes to the clinic with a
rapidly expanding target-shaped rash on his
shoulder in the same spot where he removed a
tick 3 days ago. The physician suspects Lyme
disease. Which of the following is the next step
in diagnosis?
(A) Biopsy rash and culture for Borrelia burg-
dorferi
(B) Collect plasma and culture for Borrelia
burgdorferi
(C) Collect plasma and test for Lyme antigen
(D) Collect plasma for enzyme-linked immu-
nosorbent assay and Western blot analysis
(E) Collect urine and test for Lyme antigen

it's D http://www.cdc.gov/lyme/diagnosistes...bTest/TwoStep/
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  #4  
Old 06-26-2014
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Default

Yes. D. Elisa to screen and Western blot to confirm
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  #5  
Old 06-26-2014
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Warning! unexpected answer!

I though Elisa too...but instead the book says:

The correct answer is A . This patientís rash,
erythema chronicum migrans, is suggestive of
Lyme disease, caused by the spirochete Borrelia
burgdorferi, which is transmitted by the bite
of Ixodes ticks. It is endemic in the northeastern
United States. Treatment is oral doxycycline,
amoxicillin, or cefuroxime axetil. Patients
with certain neurologic or cardiac forms
of the illness may require intravenous treatment
with drugs such as ceftriaxone or penicillin.
Cultures have only been shown to be useful
in diagnosing Lyme disease when taken
early in the course of the disease by biopsyingthe characteristic rash. It is less useful in the
case of later disease, or when used on plasma
or cerebrospinal fl uid specimens.

Answer B is incorrect. Culturing plasma is less
sensitive than culturing tissue taken from the
erythema chronicum migrans rash characteristic
of Lyme disease.

Answer C is incorrect. The Lyme antigen test
was designed to be used on urine, and does not
yield reliable results.

Answer D is incorrect. This early in the course
of the disease, ELISA and Western blot may be
falsely negative, due to the delay in seroconversion
after the initial exposure. Within 1 week
of exposure, sensitivity of ELISA and Western
blot is only 32%. After several weeks, sensitivity
rises to 87%.

Answer E is incorrect. The Lyme antigen test
is unreliable, and should not be used to support
the diagnosis of Lyme disease.
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The above post was thanked by:
rigbbm (02-19-2016), steps_8186 (06-26-2014)



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