H. Pylori: 

-  Causes most cases of PUD 

-  Most prevalent human infection in the world

Diagnosis:

-  Endoscopically: rapid urease test, histology, culture 

-  Non-endoscopically:

     -  Serologic test (IgG Ab to H. Pylori, however stays + after eradication)

     -  Urea breath test (ingest labeled urea, H. Pylori bacterial urease break it down into labeled CO2 and ammonia, later detect the labeled CO2 in the breath)

     -  Stool antigen test (>90% sens and spec, also works as test of cure >4 weeks after completing treatment). 

Treating H. Pylori will reduce recurrence of PUD

-     Triple therapy: PPI, Clarithromycin, + amoxicillin OR metronidazole for 10-14 days

-     Quadruple therapy (If resistance to Clarithromycin): PPI, bismuth, metronidazole, and tetracycline 

References:

Bjorkman, David J. “Quadruple Therapy for Helicobacter Pylori Infection.” Medscape, 28 Apr. 2011, www.medscape.com/viewarticle/740249.