Eradication of Helicobacter pylori: are rifaximin-based regimens effective?

Rifaximin is a non-absorbed semisynthetic rifamycin derivative with a broad spectrum of antibacterial activity including Gram-positive and Gram-negative bacteria, both aerobes and anaerobes. Although originally developed for the treatment of infectious diarrhea, the appreciation of the pathogenic role of gut bacteria in several organic and functional gastrointestinal diseases has increasingly broadened its clinical use. Being the antibiotic active against Helicobacter pylori, even towards clarithromycin-resistant strain, and being the primary resistance very rare, several investigations explored its potential use for eradication of the microorganism. Rifaximin alone proved to be effective, but even the highest dose (1,200 mg daily) gave a cure rate of only 30%. Dual and triple therapies were also studied, with the better results obtained with rifaximin-clarithromycin and rifaximin-clarithromycin-esomeprazole combinations. However, the eradication rates (60-70%) obtained with these regimens were still below the standard set by the Maastricht Consensus guidelines. Although rifaximin-based eradication therapies are promising, new antimicrobial combinations (with and without proton pump inhibitors) need to be explored in well-designed clinical trials including a large cohort of H. pylori-infected patients. The remarkable safety of rifaximin will allow high-dose regimens of longer duration (e.g. 10 or 14 days) to be tested with confidence in the hope of achieving better eradication rates. A drawback of rifaximin could be its inability to reach sufficiently high concentrations in the gastric mucus layer under and within which H. pylori is commonly located and this would likely affect eradication rate. Taking these considerations into account, bioadhesive rifaximin formulations able to better and persistently cover gastric mucosa, or combination with mucolytic agents, such as pronase or acetylcysteine, need to be evaluated in order to better define the place of this antibiotic in our therapeutic armamentarium.