Monitoring the treatment for H Pylori! - 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 06-22-2011
USMLE Forums Guru
 
Steps History: 1 + CS
Posts: 303
Threads: 57
Thanked 105 Times in 67 Posts
Reputation: 115
Send a message via Skype™ to usmlemydream
Bacteria Monitoring the treatment for H Pylori!

A 35-year-old has a 3-month history of epigastric pain without radiation into the back. The stool is black colored and is positive for blood. He has a past history of gastric ulcer disease due to Helicobacter pylori. Which of the following tests will identify the cause of his pain and also provide an indicator on whether treatment is effective?

Answer Choices

A. Radiolabeled urea breath test
B. Serologic test
C. Stool antigen test
D. Urease test on a gastric biopsy

whats the answer guys..have doubts abt this one
Reply With Quote Quick reply to this message
The above post was thanked by:
bebix (06-23-2011), pass7 (06-22-2011)



  #2  
Old 06-22-2011
pass7's Avatar
USMLE Forums Guru
 
Steps History: 1+CK+CS+3
Posts: 406
Threads: 30
Thanked 141 Times in 109 Posts
Reputation: 151
Default

i think C. stool antigen test. i remember once Dr. Goljan saying serology test remains positive throughout and hence cannot detect recurence
Reply With Quote Quick reply to this message
  #3  
Old 06-22-2011
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,175
Threads: 38
Thanked 852 Times in 478 Posts
Reputation: 862
Default

Quote:
Originally Posted by usmlemydream View Post
Which of the following tests will identify the cause of his pain and also provide an indicator on whether treatment is effective?
MY answer is:


A) Radiolabeled Urea Breath Test

This will clearly tell us if the ulcer is of stomach or duodenum origin (infection of H Pylori in stomach)
Reply With Quote Quick reply to this message
 
  #4  
Old 06-22-2011
USMLE Forums Guru
 
Steps History: 1 + CS
Posts: 303
Threads: 57
Thanked 105 Times in 67 Posts
Reputation: 115
Send a message via Skype™ to usmlemydream
Default

Quote:
Originally Posted by pass7 View Post
i think C. stool antigen test. i remember once Dr. Goljan saying serology test remains positive throughout and hence cannot detect recurence
you are correct
in the first go i marked this question wrong
Reply With Quote Quick reply to this message
The above post was thanked by:
pass7 (06-22-2011)
  #5  
Old 06-23-2011
USMLE Forums Guru
 
Steps History: Not yet
Posts: 417
Threads: 74
Thanked 131 Times in 94 Posts
Reputation: 141
Default

i think its A if we r looking for H pylori
Reply With Quote Quick reply to this message
  #6  
Old 06-23-2011
USMLE Forums Master
 
Steps History: Step 1 Only
Posts: 566
Threads: 25
Thanked 524 Times in 263 Posts
Reputation: 534
Default

I'll go with A also...
Reply With Quote Quick reply to this message
  #7  
Old 06-23-2011
bebix's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,357
Threads: 194
Thanked 3,261 Times in 881 Posts
Reputation: 3271
Default

Which of the following tests will identify the cause of his pain and also provide an indicator on whether treatment is effective?

Why not D) Urease test on a gastric biopsy
Urease test for H. pylori and gastric biopsy to rule out the possibility of cancer?
Reply With Quote Quick reply to this message
  #8  
Old 06-23-2011
USMLE Forums Master
 
Steps History: Step 1 Only
Posts: 566
Threads: 25
Thanked 524 Times in 263 Posts
Reputation: 534
Default

Quote:
Originally Posted by bebix View Post
Which of the following tests will identify the cause of his pain and also provide an indicator on whether treatment is effective?

Why not D) Urease test on a gastric biopsy
Urease test for H. pylori and gastric biopsy to rule out the possibility of cancer?
Because i will rather use the biopsy to assay which antibiotic use to proof sensibility or resistance to the antibiotic... Here the question ask, which of the following test provide indicator of whether tx is effective or how is going with the pte.

answer b >> Serologic test > shows if you are infected or not...

Answer a) I think is the one

I dont know, just guessing =)
Reply With Quote Quick reply to this message
The above post was thanked by:
bebix (06-23-2011)
  #9  
Old 06-23-2011
bebix's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,357
Threads: 194
Thanked 3,261 Times in 881 Posts
Reputation: 3271
Default

Quote:
Originally Posted by rulz View Post
Because i will rather use the biopsy to assay which antibiotic use to proof sensibility or resistance to the antibiotic... Here the question ask, which of the following test provide indicator of whether tx is effective or how is going with the pte.

answer b >> Serologic test > shows if you are infected or not...

Answer a) I think is the one

I dont know, just guessing =)
and how to answer "the cause of his pain" part of the question?
Reply With Quote Quick reply to this message
  #10  
Old 06-23-2011
USMLE Forums Master
 
Steps History: Step 1 Only
Posts: 566
Threads: 25
Thanked 524 Times in 263 Posts
Reputation: 534
Default

First, Remember that Urease test is a radiolabed isotope that is showing the reacting when the urea is converted to Ammoniun by ureasa organism, this ammoniun disrupt the mucosa barrier... So the more ammoniun the more pain, so if we check to the levels of urease high or low we check if the pte is getting better, no ?

That's how i think...
Reply With Quote Quick reply to this message
The above post was thanked by:
bebix (06-23-2011)
  #11  
Old 06-23-2011
bebix's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,357
Threads: 194
Thanked 3,261 Times in 881 Posts
Reputation: 3271
Default

Quote:
Originally Posted by rulz View Post
First, Remember that Urease test is a radiolabed isotope that is showing the reacting when the urea is converted to Ammoniun by ureasa organism, this ammoniun disrupt the mucosa barrier... So the more ammoniun the more pain, so if we check to the levels of urease high or low we check if the pte is getting better, no ?

That's how i think...
the only thing that bothers me is that with A) we can not know whether itīs a benign gastric ulcer...
Reply With Quote Quick reply to this message
  #12  
Old 06-23-2011
USMLE Forums Scout
 
Steps History: Not yet
Posts: 15
Threads: 0
Thanked 30 Times in 11 Posts
Reputation: 40
Default

Quote:
Originally Posted by pass7 View Post
i think C. stool antigen test. i remember once Dr. Goljan saying serology test remains positive throughout and hence cannot detect recurence

Have to go with you on this one. A radiolabled breath urease test simply confirms the presence of a urease positive organism in the stomach. Colonization does not indicate an infection. We already KNOW he has a history of H-pylori infections. His ulcerations could be caused by some other reason now and having a + urease breath test will not mean much more than simply show that he is still colonized.

As you mentioned, a positive serological antigen is also pointless since we KNOW he has been infected with H-pylori and it WILL be positive.

The only thing that can tell us with a 90% sensitivity and specificity of an ACTIVE infection is a stool-antigen test.

Since the question asks us to find a test to determine the effectiveness of the "treatment" i'm guessing this means towards the H-pylori, then the only way we can see if its effective is not to test for colonization, but to test to see if there is an active infection.

Just a little reasoning for those of you who haven't heard goljan's golden words haha.
Reply With Quote Quick reply to this message
The above post was thanked by:
leo lakhani (06-23-2011), MANIAKOS (06-23-2011)
  #13  
Old 06-23-2011
USMLE Forums Master
 
Steps History: Step 1 Only
Posts: 566
Threads: 25
Thanked 524 Times in 263 Posts
Reputation: 534
Default

Quote:
Originally Posted by spaidak2 View Post
Have to go with you on this one. A radiolabled breath urease test simply confirms the presence of a urease positive organism in the stomach. Colonization does not indicate an infection. We already KNOW he has a history of H-pylori infections. His ulcerations could be caused by some other reason now and having a + urease breath test will not mean much more than simply show that he is still colonized.

As you mentioned, a positive serological antigen is also pointless since we KNOW he has been infected with H-pylori and it WILL be positive.

The only thing that can tell us with a 90% sensitivity and specificity of an ACTIVE infection is a stool-antigen test.

Since the question asks us to find a test to determine the effectiveness of the "treatment" i'm guessing this means towards the H-pylori, then the only way we can see if its effective is not to test for colonization, but to test to see if there is an active infection.

Just a little reasoning for those of you who haven't heard goljan's golden words haha.
Yes, we all listening goljan buddy ( which i think is great) , but the stool just look at the antigen, if you have it or not, it shows the "particle" that is acting to the immune system...

The urease test addresses if you have the real "Bacteria" on your system...So the treatment is for the bacteria.... those are the different between those 2 test, why i dont go with stool antigen.. =)
Reply With Quote Quick reply to this message
  #14  
Old 06-23-2011
bebix's Avatar
USMLE Forums Master
 
Steps History: 1+CK+CS+3
Posts: 1,357
Threads: 194
Thanked 3,261 Times in 881 Posts
Reputation: 3271
Default

this is from emedicine...(thatīs why I think we should do a biopsy to "identify the cause of his pain")
"H pylori infection and NSAID use account for most cases of PUD. The rate of H pylori infection for duodenal ulcers in the United States is less than 75% for patients who do not use NSAIDs. Excluding patients who used NSAIDs, 61% of duodenal ulcers and 63% of gastric ulcers were positive for H pylori in one study. These rates were lower in whites than in nonwhites. Prevalence of H pylori infection in complicated ulcers (ie, bleeding, perforation) is significantly lower than that found in uncomplicated ulcer disease.

http://emedicine.medscape.com/article/181753-overview#aw2aab6b2b4aa"
Reply With Quote Quick reply to this message
  #15  
Old 06-23-2011
USMLE Forums Scout
 
Steps History: Not yet
Posts: 15
Threads: 0
Thanked 30 Times in 11 Posts
Reputation: 40
Default

Quote:
Originally Posted by rulz View Post
First, Remember that Urease test is a radiolabed isotope that is showing the reacting when the urea is converted to Ammoniun by ureasa organism, this ammoniun disrupt the mucosa barrier... So the more ammoniun the more pain, so if we check to the levels of urease high or low we check if the pte is getting better, no ?

That's how i think...
Don't quote me on this or take me at face value but I'd think the pain is related to h-pylori is much more complex. The pathophysiology behind the infection itself depends largely on the SITE of infection/colonization of the H-pylori.

Firstly, the damage caused by H-pylori is not just through ammonia. It is true that ammonia does indeed damage the epithelial cells plus it neutralizes the acid providing for a much less acidic pH for H-pylori to thrive in. Now we all know that H-pylori doesn't actually INVADE our cells. It does, however, release proteases, phopholipases and cytotoxins such as VacA. These further damage the underlying epithelium. It also (using a type IV secretion system, i'll leave it up to you guys to look up different secretion systems) inserts a protein called CagA. This protein massively alters gene expression inside the epithelial cells cuasing changes in cell adhesion and downstream signaling.

Sow now that we've assesed some of the more well known and researched cytotoxic effects of H-pylori, what causes the ulcers? And why are there high acid producing ulcers and low or normal acid producing ulcers? The pathophysiology depends greatly on the site of infection. If H-pylori senses higher basal acid production at the time of a primary infection, it is more likely to infect the ANTRUM of the stomach away from acid secreting parietal cells. In the antrum, it uses the above mentioned factors and induces inflammation of the underlying epithelium. This causes activation of G-cells. My best guess as to why this happens likely has to do with the body's natural response to bacteria in the stomach to further lower the pH to kill the residing bacteria. In either case, G-cells are activated causing secretion of Gastrin. Gastrin then flows through circulation and arrives BACK to the parietal cells in the body and increases acid secretion. Furthermore, chronically increased gastrin levels increase the number of parietal cells and overall acid production. The stomach is mostly well equipped to handle this high acid load and therefore doesn't likely face much damage. However, the very high acid load moves right onto the duodenum once food is digested in the stomach. The duodenum is much less equipped to handle a higher acid load and this high acid level generally tends to damage the duodenal epithelium causing DUODENAL ULCERS.


If the same H-pylori were to infect the body of the stomach where parietal cells reside, the mechanism here involves direct and chronic damage to the underlying epithelium by the bacteria causing gastric atrophy. This atrophy decreases this portion of the stomach wall to produce sufficient mucosa or deal with the acid. This therefore eventually causes GASTRIC ULCERS due to acid mediated damage on the atrophied mucosa. Due to direct destruction of parietal containing tissue, in this case we have normal to decreased acid production. This can explain why normal or lower acid/gastrin levels are associated with gastric ulcers and not duodenal ulcers.

Clearly the pain related to the PUD caused by H-pyolori is related to the ULCERS themselves being damaged by acid but the mechanisms causing the ulceration are a bit more complex.

Since we are on the topic, the increased cancer risk associated with H-pylori is also quite important. As this is one of the few associated links between a bacteria and some form of cancer. Due to the chronic stimulation damage of underlying cells (through mechanisms explained above) and due to some produced factors which actually cause increased activation of the immune system (these modulators are still under investigation), there is overall increased activity of the GALT (gastric associated lymphatic tissue). This chronic activation/activity of the GALT is thought to mediate an increased rate of mutations in the cells due to high mitotic activity from constant immune stimulation. Hence leading to cancer.

Anyways, i think this response may have been a bit long for just answering why there is pain. But I was often confused with the difference between high acid producers and low acid producers and it made no real sense until I learned this. I don't know in what detail you need to know this but I'd say at least knowing the general mechanism without all the little details can greatly increase your chances of getting even the most twisted and cruel questions correct. Hope this helps! And please correct me if i'm wrong
Reply With Quote Quick reply to this message
The above post was thanked by:
rigbbm (12-15-2016)



  #16  
Old 06-23-2011
USMLE Forums Scout
 
Steps History: Not yet
Posts: 15
Threads: 0
Thanked 30 Times in 11 Posts
Reputation: 40
Default

Quote:
Originally Posted by rulz View Post
Yes, we all listening goljan buddy ( which i think is great) , but the stool just look at the antigen, if you have it or not, it shows the "particle" that is acting to the immune system...

The urease test addresses if you have the real "Bacteria" on your system...So the treatment is for the bacteria.... those are the different between those 2 test, why i dont go with stool antigen.. =)

You answered your own question there. Having the bacteria does not necesserily mean you are infected by the bacteria. It could be that his treatment has been effective to stop active infection of H-pylori but he is still colonized. His pain could be related to some other cause. So having a positive urease test will only show that there is H-pylori trying to colonize his stomach. An infection is mediated through more invasive mechanisms than simply production of ammonia by urease. I'm not exactly sure what the antigen is that is that is targeted in the stool. But i bet the antigen is something that is produced by a H-pylori when they are actively inducing an immune response. But the "gold standard" albeit an invasive procedure would hands down be a biopsy. I'm honestly not sure what the answer could be in this case but one answer I think i'd rule out would be the urease test as it wouldn't answer the question of if the treatment was effective in stopping infection. Please voice in.
Reply With Quote Quick reply to this message
  #17  
Old 06-23-2011
dr.Irina's Avatar
USMLE Forums Veteran
 
Steps History: 1 + CK
Posts: 229
Threads: 6
Thanked 69 Times in 61 Posts
Reputation: 79
Default

i think D,agree Bebix
Reply With Quote Quick reply to this message
The above post was thanked by:
bebix (06-24-2011)



Reply

Tags
Microbiology-, Pathology-, 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
BPH Treatment? Yallah USMLE Step 1 Forum 9 06-14-2011 11:07 AM
H Pylori Eradication Therapy? Breex USMLE Step 2 CK Forum 3 06-11-2011 12:23 AM
Treatment of ITP ?? weta USMLE Step 2 CK Forum 2 08-17-2010 12:02 AM
Treatment of appendicitis? Ayshee USMLE Step 2 CK Forum 3 07-11-2010 11:54 AM
Treatment of UTI Stmf4 USMLE Step 3 Forum 2 06-09-2010 11:55 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)