From January 2009 to December 2010 , consecutive H.pylori-infected patients were randomly assigned to receive either sequential therapy ( a 5-day dual therapy with pantoprazole plus amoxicillin , followed by a 5-day triple therapy with pantoprazole plus clarithromycin and metronidazole ) or reverse sequential therapy ( a 5-day triple therapy with pantoprazole plus clarithromycin and metronidazole , followed by a 5-day dual therapy with pantoprazole plus amoxicillin ) .