'Rescue' therapies for the management of Helicobacter pylori infection.

Helicobacter pylori infection is the main cause of gastritis, gastroduodenal ulcer and gastric cancer and should be considered as a major public health issue. According to several international guidelines, first-line therapy for treating H. pylori infection consists of proton pump inhibitor (PPI) or ranitidine bismuth citrate (RBC) with any two antibiotics of amoxicillin, clarithromycin or metronidazole given for 7-14 days. However, even with the recommended treatment regimens, approximately 20% of patients will fail to obtain H. pylori eradication. The proportion of patients with first-line H. pylori therapy failure may be higher in clinical practice and it may increase thanks to diffusion of H. pylori treatment. The recommended second-line therapy is the quadruple regimen composed by tetracycline, metronidazole, bismuth salts and a PPI. However, the efficacy of this regimen is limited by poor patient's compliance due to its side effects, number of tablets per day, and long duration. Moreover, bismuth and metronidazole are not available in all countries. Alternatively, a longer-lasting (i.e. 10-14 days) PPI or RBC triple therapy with two antibiotics has generally been used. In an empirical strategy, the choice of second line depends on the treatment initially used. If a clarithromycin-based regimen was administered in first line, a quadruple regimen or PPI (or RBC) triple therapy with metronidazole and amoxicillin (or tetracycline) should be suggested as a second line. In case of second-line treatment failure, the patient should be evaluated by a case-by-case approach. A susceptibility-guided strategy, if available, is recommended in order to choose the best third-line treatment. Culture can reveal the presence of H. pylori-sensitive strains to clarithromycin (the best effective) or other antimicrobials (such as amoxicillin, metronidazole and tetracycline). Conversely, in an empirical strategy, a third-line not yet used therapy, can reach a high success rate. PPI or RBC, amoxicillin and a new antimicrobial (e.g. rifabutin, levofloxacin or furazolidone) could be used. Several studies have obtained relatively good results with triple therapy combining PPI, rifabutin, and amoxicillin, although a reversible myelotoxicity as leukopenia and thrombocytopenia has been described. Preliminary good results were also achieved with triples PPI regimens combining levofloxacin and amoxicillin without important adverse effects. Furazolidone has also shown efficacy for H. pylori eradication, although untoward reactions could limit its use, especially when high doses are employed. Finally, in more than one H. pylori treatment failure, non-antimicrobial add-on medications (such as lactoferrin, probiotics and others) could be used with the aim either to improve the eradication rate or to minimize side effects.