Second-line Therapy for Helicobacter Pylori Eradication: State of the Art.

Helicobacter pylori (H. pylori) is a Gram negative spiraliform bacterium that colonizes the human stomach. It is the most common cause of chronic gastritis, peptic ulcer, and gastric carcinoma. The eradication therapy is based on the combination of a proton pump inhibitor and several antibiotics such as amoxicillin, metronidazole, clarithromycin, levofloxacin or tetracycline. The most commonly used regimens for eradication in the first line are triple, sequential and concomitant therapy, despite the last European Guidelines suggesting a quadruple therapy already at the first attempt in areas with high resistance rates. However, the rise in antibiotic resistance is the main reason for a marked increase in first-line therapy failure. Clarithromycin resistancea, is especially acknowledged as the most important event resulting in failure. Up to 20% of patients are intended not to eradicate, therefore they will need a second line therapy. Currently, the most used rescue regimens are levofloxacin-based triple therapy and bismuth-containing quadruple therapy, despite guidelines suggesting to use a combination of antibiotics that have not been included in previous treatments. Nitazoxanide is a novel antibiotic with promising results. Additionally, an interesting field worth of investigation is the antibiotic susceptibility based approach, which could help choose antibiotics with confirmed effectiveness in vitro. Analysis of antibiotic resistance may be performed by both bacterial culture and molecular biology techniques, able to detect point mutations conferring resistance. This is a particularly interesting approach, since it may personalize the therapy, thus optimizing the regimen and maximizing the probability of success.