Zaful Dresses

Stool Antigen Testing: critical factors to consider.

Background and Clinical Significance

  •  H. pylori is a spiral-shaped Gram negative bacterium that infects about 3 billion people worldwide 
  •  Most people are infected as children
  • Colonizes the stomach and duodenum indefinitely 
  •  Infection increases linearly with age > 40% age over 60 years
  •  HP has been classified as group I carcinogen for gastric carcinoma by the World Health Organization 
  •  HP-infected individual has 2-8 times higher risk of gastric carcinoma than the general population 
  •  Stomach cancer causes about 800,000 deaths worldwide per year
 Common in East Asia and Eastern Europe World Cancer Report 2014. World Health Organization

Mode of transmission:
  •  fecal-oral 
  •  person to person 
  • contaminated water 
  •  contaminated food 
  •  zoonotic – (domestic cats, primates, sheep)
Clinical Outcomes of Helicobacter pylori infections

  • Greater than  80% of people infected will be asymptomatic 
  •  15 - 20%  will suffer from chronic gastritis, gastric ulcer or duodenal ulcer
  • Less than 1% of people will develop gastric cancer
Source: Dr. Hagmeyer

The prevalence rates of Helicobacter pylori (H. pylori) infection in the US

60% of Hispanics, 54% of African Americans, and  20% Caucasians are affected.

  •  New Mexico 15-20% 
  • New York 15-20% S
  • outh Carolina ≥20% 
  • Puerto Rico ≥20% 
  • llinois 15-20% 

Sonnenberg et al. (2010). A National Study of Helicobactor pylori Infection in Gastric Biopsy Specimens
Prevalence of H. pylori in Africa and East Asia

Why Stool Antigen Testing?

  •  Simple 
  • Cost-effective 
  • High Sensitivity and Specificity 

  • Diagnose an active infection
  •  Confirm eradication of H. pylori after treatment
  • Eradication reduces risk of gastric cancer

 Pit falls

  •  False negative result in patients who are taking PPIs antibiotics or bismuth 
  •  Inadequate sample volume 
  •  False positive result in patients with acute upper gastrointestinal bleeding 
  •  H. pylori antigen testing appears to be more accurate at detecting eradication when performed 4 - 8 weeks

 Data Interpretation

 Why cut-off value?

  •  H pylori is genetically highly diverse
  •  Several strains, variation in virulence factors depending on geographic location
CagA gene differs between isolates from East Asia versus Europe and North America iceA1 found in Asian countries; iceA2 found in Western countries Particular variants of vacA, such as vacA s1/m1 restricted to East Asia. (Shiota et al., 2013)
  • Cut-off values for EIA testing set by manufacturers not representative of samples

 Other Factors to Consider

  • Country of origin/birth Geographic location and prevalence of H. pylori 
  • Age 
  • Frequency of travel
  • Travel destination

Robin Warren (left) Barry Marshal(right). Won the Nobel prize in physiology in 2005 for their discovery of H. pylori in 1981. 

To treat or not to treat: Helicobacter pylori: Friend or foe?

  • Antibiotic Resistance Adverse effects- anaphylaxis Clostridium difficile infection
  •  Treatment tops $32 billion in the US 
  • Protection from gastroesophageal reflux disease and esophageal adenocarcinoma 
  • H. pylori has been colonizing the human stomach for more than 58,000 years 
  • What if you alter the colonization of the fecal microbiome? 
  • Inverse relationship between H. pylori infection and asthma, allergies (Malnick et al., 2014) Possible protection from Multiple Sclerosis (Mohebi et al., 2013) 


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