Group (B) Patient who fail from bismuth quadruple therapy will be retreated with levofloxacin sequential therapy for 14days D1-D7: (esomeprazole 40mg bid + amoxicillin 1gm bid) for 7 days D8-D14: (esomeprazole 40mg bid + levofloxacin 250mg bid + metronidazole 500mg bid) for another 7 days