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  #1  
Old 02-24-2011
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Bacteria VDRL Positive Patient, what to do?

The laboratory reports that the Venereal Disease Research Laboratory (VDRL) test performed on a patient is reactive at a dilution of 1:4 (4 dils). The patient also reports to you that he has recently been diagnosed with hepatitis A. Which one of the following actions would be most appropriate?

a. Report this patient to the health department, as he has syphilis
b. Order a confirmatory test such as the fluorescent treponemal antibody test (FTA)
c. Repeat the VDRL test
d. Order a rapid reagin test (RPR)
e. Perform a spinal tap to rule out central nervous system syphilis
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  #2  
Old 02-24-2011
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Default ans

b) order for FT abs confirmtory for syphilis
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  #3  
Old 02-24-2011
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The results of many immunologic tests are expressed as a titer, which is defined as the highest dilution of the specimen, e.g., serum, that gives a positive reaction in the test. Note that a patient's serum with an antibody titer of, for example, 1/64 contains more antibodies, i.e., is a higher titer, than a serum with a titer of, for example, 1/4.

With a titer of 1/4, results are inconclusive, so we need to repeat the test.

My choice is C.
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Old 02-24-2011
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Default B

I say B because the VDRL test is not specific, and since the patient has another infection (HepA) this result may be a false positive. Ordering a more specific test will determine whether the patient really has syphilis.

I don't think it's C because repeating the VRDL test won't provide any new info; even if it came back with higher titers, again it could be false positive and you would still need to do a more specific test.

It's not e because CNS syphilis is tertiary and you would likely see other CNS symptoms (eg tabes dorsalis), plus you wouldn't do a LP on this person just to figure this out since there is no reason to believe he has CNS infection.
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Old 02-24-2011
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Default B

Quote:
Originally Posted by heights View Post
I say B because the VDRL test is not specific, and since the patient has another infection (HepA) this result may be a false positive. Ordering a more specific test will determine whether the patient really has syphilis.

I don't think it's C because repeating the VRDL test won't provide any new info; even if it came back with higher titers, again it could be false positive and you would still need to do a more specific test.

It's not e because CNS syphilis is tertiary and you would likely see other CNS symptoms (eg tabes dorsalis), plus you wouldn't do a LP on this person just to figure this out since there is no reason to believe he has CNS infection.
i agree with heights...good explanation....i think the answer is b
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  #6  
Old 02-24-2011
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Default B

I would also go with B because VDRL and RPR both can have false positives in the setting of other infections such as hepatitis so a more specific test for syphilis should be used.

A doesnt make sense and E is not indicated because the question says nothing to imply the patient has tertiary syphilis or even secondary syphilis.
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  #7  
Old 02-24-2011
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Arrow B) Order a confirmatory test such as the fluorescent treponemal antibody test (FTA)

My ans is B) Order a confirmatory test such as the fluorescent treponemal antibody test (FTA).

let me tell you the reason in a bit...

The FTA-ABS test is most reliable and is reportedly positive in 100% of cases.

The FTA-ABS test is often used as a confirmatory test after first screening a patient with a VDRL (Venereal Disease Research Laboratory) or RPR (rapid plasma reagin) test, since the FTA-ABS test is more expensive and time-consuming than "non-treponemal" syphilis tests such as the VDRL and RPR.
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  #8  
Old 02-24-2011
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Default B

Me too B, same explanation as others!!
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  #9  
Old 02-25-2011
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Default thanks guys for ur answers

correct ans s B..
exp

There are two kinds of tests for the detection of syphilis antibodies: nonspecific
tests such as the RPR and VDRL, and specific tests such as the
FTA, TPHA (Treponema pallidum hemagglutination test), and the MHTP
(microhemagglutination-T. pallidum). The difference is that the nonspecific
tests use a cross-reactive antigen known as cardiolipin, while the
specific tests use a T. pallidum antigen. Although the nonspecific tests are
sensitive, they lack specificity and often cross-react in patients who have
90 Microbiology
diabetes, hepatitis, infectious mononucleosis, or who are pregnant. Some
patients, especially those with autoimmune diseases, will have both nonspecific
(RPR) and specific tests (FTA) positive. Resolution of such a situation
can be done by molecular methods for T. pallidum such as PCR,
or by the immobilization test using live spirochetes and the patientís
serum. In the TPI test, the spirochetes will die in the presence of specific
antibody.
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  #10  
Old 02-25-2011
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It has nothing to do with this question. But thought it was a good idea to squeeze it in. 10-30 % of lupus patients have the "anti-coagulant syndrome" manifested by prolonged PTT and false positive VDRL...
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  #11  
Old 02-25-2011
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Quote:
Originally Posted by Guki View Post
It has nothing to do with this question. But thought it was a good idea to squeeze it in. 10-30 % of lupus patients have the "anti-coagulant syndrome" manifested by prolonged PTT and false positive VDRL...
Also have a look here
False Positive VDRL
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Quote:
Originally Posted by Hokolesqua View Post
Also have a look here
False Positive VDRL
Nice one. I am adding this one to my notes.
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