Emerging evidence suggest that vitamin D might be a cost-effective prophylactic and possibly therapeutic antimicrobial agent for the control and eradication of H. pylori. Since vitamin D acts through mechanisms independent of standard antibiotics, it is expected that vitamin D will be equally efficacious for controlling and eradicating drug-resistant strains of H. pylori. The investigators herein propose that vitamin D in combination of standard antimicrobial therapeutics could improve the eradication rates of drug-resistant H. pylori.