Quadruple therapy is effective for eradicating Helicobacter pylori after failure of triple proton-pump inhibitor-based therapy: a detailed, prospective analysis of 21 consecutive cases

Background. Data regarding the effectiveness of second-line treatment of Helicobacter pylori infection are limited, especially if microbiological studies are considered.
Methods and Patients. We conducted a prospective, uncontrolled study of a consecutive series of 21 peptic ulcer patients with failure of 1-week lansoprazole, amoxicillin, and clarithromycin. H. pylori status was evaluated by urease test, histology, culture, and urea breath test. Susceptibility to amoxicillin, clarithromycin, and metronidazole was studied by E -test. Cure of infection was defined as negative results from endoscopy-based tests 1 month after treatment and negative results from a urea breath test at 2 months. Treatment consisted of a 1-week combination of lansoprazole (30 mg bid), tetracycline (500 mg qid), metronidazole (500 mg tid), and bismuth subcitrate (120 mg qid).
Results. H. pylori was resistant to metronidazole in three cases, to clarithromycin in three cases, and to both clarithromycin and metroinidazole in an additional three patients. No resistance to amoxicillin was found. Eradication was obtained in 20 cases (95.2% confidence interval CI], 76.2–99.9). The only patient in whom infection was not eradicated harbored a metronidazole-resistant (minimum inhibitory concentration> 32 μg/ml) strain. No significant side effects were reported.
Conclusion. Quadruple therapy obtains a high eradication rate even in patients with clarithromycin- and metronidazole-resistant strains. Further randomized and controlled studies are warranted and are urgently needed.