Incidence of secondary Helicobacter pylori resistance to antibiotics in treatment failures after 1-week proton pump inhibitor-based triple therapies:a prospective study

Background. Antibiotic-resistant Helicobacter pylori strains are becoming i ncreasingly prevalent, although it is not clear to what extent the new resi stant organisms will spread. Aim. To evaluate the incidence of secondary Helicobacter pylori resistance to metronidazole, clarithromycin and/or amoxycillin after one-week proton p ump inhibitor based triple therapy failure in patients who were, before the rapy, infected with Helicobacter pylori strains susceptible to these antibi otics. Patients and Methods. Enrolled in the study were 97 consecutive Helicobacte r pylori-positive subjects infected by Helicobacter pylori strains suscepti ble to metronidazole, clarithromycin and amoxycillin. Activity of tested an tibiotics was determined by means of the E-test. Patients were treated for seven days with a proton pump inhibitor: omeprazole 20 mg twice daily or pa ntoprazole 40 mg once daily, plus clarithromycin 250 mg twice daily and met ronidazole 250 mg four times daily; or with a proton pump inhibitor plus am oxycillin 1 g twice daily and clarithromycin 500 mg twice daily Two months after completion of therapy, endoscopy and gastric biopsies for histology, rapid urease test and culture were repeated. Results. Four patients were dropped from the study Overall Helicobacter pyl ori cure rates expressed as both intention-to-treat and per-protocol analys es, were, respectively, 80% (40/50) and 81.6% (40/49) with proton pump inhi bitor clarithromycin and metronidazole and 76.6% (86/47) and 81.8% (36/44) with proton pump inhibitor: amoxycillin and clarithromycin. No significant differences were observed between the two treatments. Subjects in whom trea tment failed were significantly younger and had less active ulcer than cure d patients. Of treatment failures, 70.6% (12 out of 17 subjects) developed a secondary resistance to metronidazole (35.3%) and/or clarithromycin (64.7 0%). Secondary antibiotic resistance occurred in 77.8% of treatment failure s treated with proton pump inhibitor clarithromycin and metronidazole and i n 62.5% of those treated with proton pump inhibitor; amoxycillin and clarit hromycin. Considering all patients treated, the overall incidence of second ary metronidazole and/or clarithromycin resistance after therapy was report ed in 12.9% of subjects (12 out of 93 treated patients). Conclusions. Secondary Helicobacter pylori resistances to metronidazole and /or clarithromycin occurred in large percentages in patients with treatment failure after the one-week proton pump inhibitor-based triple therapies, p roton pump inhibitor: clarithromycin and metronidazole and proton pump inhi bitor amoxycillin and clarithromycin. It is likely that new antibiotics or treatment strategies will be needed in the near future to successfully trea t Helicobacter pylori infection.