Since 1982, Helicobacter pylori had been discovered and established as a common cause of gastritis, peptic ulcer disease and also closely associated with several gastric malignancies and then had consequently been designated a human carcinogen.
Due to heightened awareness regarding testing for and eradication of infection, the prevalence and incidence of H pylori infection appear to have declined in recent years. However, antimicrobial resistance is mounting; the overall H. pylori antibiotic resistance rates were 17.2% for clarithromycin, 26.7% for metronidazole, 11.2% for amoxycillin, 16.2% for levofloxacin, 5.9% for tetracycline, 1.4% for rifabutin and 9.6% for multiple antibiotics. The worldwide H. pylori antibiotic resistance towards different antibiotics has increased. Such a phenomenon has affected therapeutic management in different countries. In developed countries, the most popular treatment regimen remains traditional clarithromycin- or metronidazole-containing triple therapies consisting of a proton pump inhibitor and amoxicillin for 7 to 14 days. With the rising prevalence of antimicrobial resistance, the eradication rates with traditional triple therapy are disappointing, with treatment success rate less than 80% of those treated.
A growing challenge facing today's clinicians is the management of patients with persistent H pylori despite previous attempts to treat the infection. Novel first-line anti-H. pylori therapies in 2011 include sequential therapy, hybrid therapy, concomitant quadruple therapy and bismuth-containing quadruple therapy. After the failure of standard triple therapy, a bismuth-containing quadruple therapy comprising a proton pump inhibitor (PPI), bismuth, tetracycline and metronidazole can be employed as rescue treatment. Recently, triple therapy combining a PPI, levofloxacin and amoxicillin has been proposed as an alternative to the standard rescue therapy. This salvage regimen can achieve a higher eradication rate than bismuth-containing quadruple therapy in some regions and has less adverse effects. The best second-line therapy for patients who fail to eradicate H. pylori with first-line therapies containing clarithromycin, amoxicillin and metronidazole is unclear. These commonly used regimens for the eradication of Helicobacter pylori infection consist of administration of proton pump inhibitors (PPIs) and 1 to 3 antimicrobial agents, such as amoxicillin, clarithromycin, metronidazole, fluoroquinolone, or tetracycline. PPIs are metabolized by cytochrome P450 2C19 (CYP2C19), which is polymorphic. CYP2C19 genotypic differences in the pharmacokinetics and pharmacodynamics of PPIs influence the eradication rates of H. pylori infection by PPI-containing regimens. Most guidelines suggest that patients requiring third-line therapy should be referred to a medical center and treated according to the antibiotic susceptibility test. Nonetheless, an empirical therapy (such as levofloxacin-based or furazolidone-based therapies) can be employed to terminate H. pylori infection if antimicrobial sensitivity data are unavailable.
Clinicians should use 'only use what works locally' and ignore consensus statements and society guidelines if they are not consistent with local results.

SUMMARY:
Treatment of H. pylori infection is challenged by a dramatic fall in eradication rates all over the world. Newer regimens have been introduced including sequential, hybrid therapy, quadruple therapies and those regimens provide promising results, but the knowledge about local resistance rates remains the key to an effective therapy. To achieve consistently high eradication rates, the eradication regimens must be designed based on a good understanding of the resistance patterns of the bacteria and the pharmacologic characteristics of the agents used for H. pylori eradication therapy.