HIV Diagnosis Question - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
Home
USMLE Articles
USMLE News
USMLE Polls
USMLE Books
USMLE Apps
Go Back   USMLE Forums > USMLE Step 1 Forum

USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 12-02-2009
USMLE Forums Veteran
 
Steps History: ---
Posts: 238
Threads: 56
Thanked 203 Times in 61 Posts
Reputation: 233
Question HIV Diagnosis Question

This is a question which I got from USMLE Rx which I got it wrong and I do not agree with the answer, maybe cuz I got my concepts wrong?

32-year old woman, has Pneumocystis jiroveci infection. Physician suspects patient may have HIV. WHich of the following lab techniques could determine if patient has HIV infection?

A) Northern blot
B) Southern blot
C) Western blot
D) PCR
E) RFLP

Answer was Western blot. But shouldn't PCR be a much better test?
Reply With Quote Quick reply to this message



  #2  
Old 12-02-2009
USMLE Forums Scout
 
Steps History: Step 1 Only
Posts: 82
Threads: 4
Thanked 80 Times in 30 Posts
Reputation: 90
Default

I think it should be reverse transcriptase PCR not PCR to pick up HIV
but am not sure
Reply With Quote Quick reply to this message
  #3  
Old 12-02-2009
YoramFishke's Avatar
USMLE Forums Veteran
 
Steps History: 1+CK+CS
Posts: 248
Threads: 11
Thanked 311 Times in 127 Posts
Reputation: 341
Default

First of all I do agree with GNND85 that HIV being an RNA virus it needs RT-PCR not regular PCR.
But I don't think that's the reason the answer is wrong.
They wanted to tell you that in clinical practice we start with a cheaper more practical option which is either ELISA or Western blot specially if the case can be diagnosed by such techniques (as opposed to a newborn of HIV positive mother or recent exposure like needle stick for example).

Second, USMLERx usually explains each and every option, so what did they say about the PCR choice!

Third, USMLERx is know to have several "wrong" questions and that's why they put a feedback with each question and you can send them feedback about that question.
Reply With Quote Quick reply to this message
The above post was thanked by:
DrSeddik (12-03-2009)
 
  #4  
Old 12-02-2009
USMLE Forums Newbie
 
Steps History: ---
Posts: 6
Threads: 0
Thanked 2 Times in 2 Posts
Reputation: 12
Default

The screening tests for HIV are antibody tests: ELISA confirmed by Western Blot. The Reverse Transcrpitase PCR is only used in special circumstances: 1. for infants of HIV positive mothers (antibodies screening is not helpful here). 2. for accidental needle prick of healthcare workers.
Reply With Quote Quick reply to this message
The above post was thanked by:
Rookie (03-20-2012)
  #5  
Old 12-04-2009
USMLE Forums Veteran
 
Steps History: ---
Posts: 238
Threads: 56
Thanked 203 Times in 61 Posts
Reputation: 233
Default

Ahh I see.

Regarding what did they say bout the wrong option, I don't remember the exact explanation, but bascially, that question wasn't explained well in Rx.
Reply With Quote Quick reply to this message



Reply

Tags
Molecular-Biology-, Step-1-Questions

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Location
Where you live. Leave blank if you don't want to tell.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
What is the most likely diagnosis? aktorque USMLE Step 1 Forum 12 07-13-2015 02:44 AM
What's your Diagnosis? sohailus USMLE Step 2 CK Forum 4 12-15-2012 09:53 PM
Which of the following is the most likely diagnosis? tyagee USMLE Step 2 CK Forum 3 06-06-2012 01:45 PM
HIV diagnosis: PCR vs RT-PCR? Dr.NickRiviera USMLE Step 1 Forum 2 05-22-2012 02:01 PM
What is your diagnosis? aktorque USMLE Step 1 Forum 12 02-15-2011 11:38 AM

RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)