A 65-year-old man is evaluated after a positive stool antigen test for Helicobacter pylori infection obtained to confirm eradication after therapy. H. pylori gastritis was diagnosed in the setting of a duodenal ulcer. Four weeks ago, he completed a 10-day course of eradication therapy consisting of amoxicillin, clarithromycin, and omeprazole. He reports taking all medications as prescribed during treatment and reports no upper gastrointestinal symptoms or melena. The patient does not smoke cigarettes or drink alcohol. He has no known drug allergies.
Which of the following is the most appropriate 14-day treatment regimen?
A. Amoxicillin, clarithromycin, and omeprazole
B. Amoxicillin, metronidazole, and omeprazole
C. Bismuth, metronidazole, omeprazole, and tetracycline
D. Clarithromycin, metronidazole, and omeprazole
MKSAP Answer and Critique
The correct answer is C. Bismuth, metronidazole, omeprazole, and tetracycline. This content is available to MKSAP 18 subscribers as Question 93 in the Gastroenterology and Hepatology section. More information about MKSAP is available online.
Bismuth, metronidazole, omeprazole, and tetracycline for 14 days is the most appropriate treatment regimen for this patient. The salvage therapy regimen should consist of different antibiotics from those used in the initial, unsuccessful regimen. This strategy reduces the likelihood of antibiotic resistance, the major reason for treatment failure.
Additional factors in choosing salvage therapy after initial treatment failure include a history of quinolone antibiotic use and penicillin allergy. If the initial unsuccessful treatment was clarithromycin triple therapy and the patient is allergic to penicillin, the best salvage therapy is a bismuth quadruple therapy (bismuth, metronidazole, omeprazole, and tetracycline). In patients with no penicillin allergy, but whose history includes quinolone antibiotic use for any reason, salvage therapies could include bismuth quadruple therapy, rifabutin triple therapy (rifabutin, penicillin, and a proton pump inhibitor [PPI] such as omeprazole) or high-dose dual therapy (amoxicillin and a PPI). Disruption of therapy can cause treatment failure, and the likelihood of treatment success diminishes with each successive treatment attempt. It is essential to counsel the patient carefully on the importance of treatment adherence and potential side effects of the therapy.
Treatment with the same regimen (amoxicillin, clarithromycin, and omeprazole) for a longer period of time will be ineffective because the patient's Helicobacter pylori infection is likely resistant to clarithromycin and/or penicillin.
The combination of amoxicillin, metronidazole, and omeprazole is not a recognized treatment regimen for H. pylori in any setting. Metronidazole is typically used in patients with penicillin allergy.
Using metronidazole rather than amoxicillin is unlikely to result in H. pylori eradication because resistance to clarithromycin is also a likely cause of the initial treatment's failure. Furthermore, the regimen of clarithromycin, metronidazole, and omeprazole could lead to the development of metronidazole resistance in the likely event of treatment failure with this regimen.
- For Helicobacter pylori infection that persists after eradication therapy, the salvage therapy regimen should consist of different antibiotics from those used in the initial, unsuccessful regimen.